A Review of PV Inverter
Technology Cost and
Performance Projections

Final Presentation Report to

National Renewable Energy Laboratory

Text Box: Navigant Consulting Inc.
77 South Bedford Street
Burlington, MA 01803
www.navigantconsulting.com
Navigant Consulting Inc.
77 South Bedford StreetBurlington, MA 01803www.navigantconsulting.com
Text Box: This work was supported by the U.S. Department of Energy’s (U.S. DOE) Office of Energy
Efficiency and Renewable Energ
This work was supported by the U.S. Department of Energy’s
(U.S. DOE) Office of Energy Efficiency and Renewable Energy
(EERE) under National Renewable Energy Laboratory (NREL)
Contract No. KACX-4-44451-04
Text Box: January 2006
January 2006

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Future Performance and Cost Estimates
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Historical Perspective
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Challenges for Achieving Future Targets
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Addressing the Challenges
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Introduction
Text Box: Table of Contents
Table of Contents
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Suggested Role for Government
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Executive Summary
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Future Performance and Cost Estimates
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Historical Perspective
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Challenges for Achieving Future Targets
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Addressing the Challenges
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Bevel: Introduction
Introduction
Text Box: Table of Contents
Table of Contents
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Suggested Role for Government
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Executive Summary

Navigant Consulting Inc. (NCI) evaluated PV inverter technology and
cost improvements required to meet U.S. DOE goals for 2020.

Text Box: Executive Summary Study Objective
Executive Summary Study Objective
Text Box: The National Renewable Energy Laboratory (NREL) has a major responsibility in the
implementation of the U.S. Departme
•The National Renewable Energy Laboratory (NREL) has a major responsibility in the
implementation of the U.S. Department of Energy’s (DOE’s) Solar Energy Technologies
Program. Sandia National Laboratories (SNL) has a major role in supporting inverter
development, characterization, standards, certifications, and verifications.
•The Solar Energy Technologies Program recently published a Multiyear Technical Plan,
which establishes a goal of reducing the Levelized Energy Cost (LEC) for photovoltaic
(PV) systems to $0.06/kWh by 2020.
•The Multiyear Technical Plan estimates that, in order to meet the PV system goal, PV
inverter prices will need to decline to $0.25-0.30 Wp by 2020.
•DOE determined the need to conduct a rigorous review of the PV Program’s technical
and economic targets, including the target set for PV inverters.
•NREL requested that NCI conduct a review of historical and projected cost and
performance improvements for PV inverters, including identification of critical barriers
identified and the approaches government might use to address them.

NREL’s questions regarding PV inverter cost and performance, andthe
role they should play, were broken down into three key questions.

* This includes the question: “Will inverters reach the cost goal set by the Solar Energy Technologies
Program?”

Text Box: Executive Summary Key Issues Addressed
Executive Summary Key Issues Addressed
Text Box: What are the critical cost and performance improvement needs for PV inverters that government
should support to promo
What are the critical cost and performance improvement
needs for PV inverters that government should support to
promote PV market growth?
Do PV inverters face
challenges in meeting the
U.S. DOE’s Solar Energy
Technologies Program
targets?*
Is there a clear
understanding and
consensus for addressing
key PV inverter
challenges?
What role should
government play in
addressing the key
challenges that PV
inverters face?

Many potential roles for government were identified that can help to
improve the chances that DOE program targets are achieved.

Text Box: Executive Summary Key Issues Addressed
Executive Summary Key Issues Addressed
Text Box: What are the critical cost and performance improvement needs for PV inverters that government
should support to promo
What are the critical cost and performance improvement
needs for PV inverters that government should support to
promote PV market growth?
Do PV inverters face
challenges in meeting DOE’sSolar Energy Technologies
Program targets?*
Is there a clear understanding
and consensus for addressing
key PV inverter challenges?
What role should government
play in addressing the key
challenges that PV inverters
face?
•Sales-volume increases and
learning-curve improvements
alone appear unlikely to achieve
the targeted inverter selling price
of $0.25-0.30/W by 2020.
•Inverter lifetimes greater than 15
years appear difficult to achieve.
•Improvements in manufacturing,
design, and technology are
needed to achieve the price and
performance targets.
•Reducing regulatory complexity
and long-term, consistent policy
will also be required.
•Manufacturers and industry
experts do not agree on needs to
address key inverter challenges.
•Support is needed in several
areas:
-Manufacturing and testing
improvements: process
improvement, training, quality
management, HALT/HASS
assistance, and documenting field
performance data.
-Design: alternative topologies,
thermal management, modeling,
and DER inverters.
-Technology: advanced switching,
capacitors, and components.
•Assistance with testing
methodologies for inverter
ratings. Access to training in
manufacturing processes and
quality control. Support to
understand field performance
and failure data.
•Support for public-private
partnerships for R&D on new
technologies, topologies, and
modeling.
•Information and analysis to support:
-Evaluation of regulatory and
safety requirements.
-Evaluation of alternative policy
approaches.

Achieving the targeted improvements of lower cost and higher
reliability for inverters is not a foregone conclusion for the industry.

•Based on learning-curve forecasts, the targeted cost reductions for 2020 will not be
achieved with current market growth and learning-rate levels.
..Significant uncertainty exists around the potential for future market growth to
exceed current levels for an extended period of time.
..Additional cost reductions will require an acceleration of learning effects.
..Inverter prices have been dropping by about 10% with every doubling of
cumulative production, compared to 20% for PV modules.
•Reliability and life issues for inverters have the potential to damage the reputation of
the industry and long-term adoption of PV.
..Because of market demands, manufacturers today are focused on lowering first cost
over improving reliability.
..Reliability and life improvements may not be achieved with consistency across the
industry.


Text Box: Executive Summary Future Performance
Executive Summary Future Performance
Text Box: ? In order to increase the probability of achieving the goals of industry, which are necessary for
the PV market to b
..In order to increase the probability of achieving the goals of industry, which are
necessary for the PV market to become sustainable over the long term, ongoing
government support for inverter R&D is likely to be necessary.

NCI’s assessment is that there is an important role for government
to support PV inverter improvements for the next several years.

•In general, larger companies in the PV inverter business view the role of government in providing
assistance (via programs to reduce cost and increase reliability) as being less critical to their success
and the long-term future of the industry.
—Most larger companies that NCI spoke to believe that increasing sales volume is the single largest
factor that will lead to lower cost and higher reliability for PV inverters.
•Despite the views of larger companies, introducing a new inverter product has proven to be a risky
venture for some large companies. For example:
—Xantrex experienced significant problems with their early PV inverters and ended up losing
market share to new European market entrants.
—Philips entered the PV inverter market in Europe, only to exit afew years later after experiencing
significant technical problems with their first product.
•The PV market will be in a critcal growth phase during the next5-10 years, continuing to require
significant policy and market support to achieve the overall cost and performance required for a
sustainable market.
•If small manufacturers have more dificulty meeting the reliability requirements of the market and
cannot afford to provide adequate after-sales service, it could hurt the PV industry as a whole
(inadequately performing inverters will hurt the industry).
•While some consolidation in the inverter business should be expected, the benefits of competition and
innovation provided by the smaller companies are likely to be important to the industry at its current,
early stage of development.


Text Box: Executive Summary Overcoming Key Challenges
Executive Summary Overcoming Key Challenges

Long-term cost reduction and performance improvements will benefit
greatly from the ongoing support of additional government programs.

Text Box: Executive Summary Suggested Role for Government
Executive Summary Suggested Role for Government
Text Box: Inverter testing at Sandia National Labs is extremely valuable to the industry, and continued
support of development
•Inverter testing at Sandia National Labs is extremely valuable to the industry, and continued
support of development of testing protocols is important to the industry.
•Documentation of failure analysis in the industry is not conducted uniformly. A possible role
for government would be in collecting and documenting inverter failures to share with the
industry.
•Modeling tools would be helpful to manufacturers, but developingaccurate models is
challenging. An assessment of issues and needs related to modeling would be appropriate
before embarking on new modeling efforts.
•The High Reliability Inverter Initiative (HRII) program is generally considered to have been
successful. Follow-on public-private R&D partnerships such as this should continue to receivegovernment
support.
•Cost and efficiency benefits of tranformerless inverters are understood. Studies on the pros
and cons of tranformerless inverters as a means of educating inspectors and regulators would
be beneficial to encourage adoption of regulations and codes that allow their use.
•Analysis of the interaction of the various federal, state, and municipal support programs will
be increasingly important to future industry growth needed for long-term success.

Several issues identified are common to all DER inverters and could
be addressed as part of crosscutting research programs.

Text Box: Executive Summary Suggested Role for Government
Executive Summary Suggested Role for Government
Text Box: Comprehensive information on inverter components (capacitors, electrical connectors, power
semiconductors, etc.) and
•Comprehensive information on inverter components (capacitors, electrical connectors,
power semiconductors, etc.) and options would assist manufacturers in identifying the
best products.
•Innovative inverter topologies have been suggested to provide many benefits. A role
for government may be in support of experimental topologies as ameans of advancing
the industry.
•Manufacturers would benefit from understanding the costs and benefits of the Highly
Accelerated Life Testing (HALT) and Highly Accelerated Stress Screening (HASS)
testing programs. Government could assist by providing general guidelines and

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Future Performance and Cost Estimates
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Historical Perspective
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Challenges for Achieving Future Targets
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Addressing the Challenges
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Bevel: Introduction
Introduction
Text Box: Table of Contents
Table of Contents
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Bevel: Suggested Role for Government
Suggested Role for Government
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Bevel: Executive Summary
Executive Summary

Navigant Consulting Inc. (NCI) evaluated the PV inverter technology
and cost improvements required to meet U.S. DOE goals for 2020.

Text Box: Introduction Objective
Introduction Objective
Text Box: The National Renewable Energy Laboratory (NREL) has a major responsibility in the
implementation of the U.S. Departme
•The National Renewable Energy Laboratory (NREL) has a major responsibility in the
implementation of the U.S. Department of Energy’s (DOE’s) Solar Energy Technologies
Program. Sandia National Laboratories (SNL) has a major role in supporting inverter
development, characterization, standards, certifications, and verifications .
•The Solar Energy Technologies Program recently published a Multiyear Technical Plan,
which establishes a goal of reducing the Levelized Energy Cost (LEC) for photovoltaic
(PV) systems to $0.06/kWh by 2020.
•The Multiyear Technical Plan estimates that, in order to meet the PV system goal, PV
inverter prices will need to decline to $0.25-0.30 Wp by 2020.
•DOE determined the need to conduct a rigorous review of the PV Program’s technical
and economic targets, including the target set for PV inverters.
•NREL requested that NCI conduct a review of historical and projected cost and
performance improvements for PV inverters, including identification of critical barriers
identified and the approaches government might use to address them.

NREL’s key questions regarding PV inverter cost and performance,and
the role they should play, can be broken down into three key questions.

* This includes the question: “Will inverters reach cost goal set by the Solar Energy Technologies Program?”

Text Box: Introduction Issues Analysis
Introduction Issues Analysis
Text Box: What are the critical cost and performance improvement needs for PV inverters that government
should support to promo
What are the critical cost and performance improvement
needs for PV inverters that government should support to
promote PV market growth?
Do PV inverters face
challenges in meeting the
U.S. DOE’s Solar Energy
Technologies Program
targets?*
Is there a clear
understanding and
consensus for addressing
key PV inverter
challenges?
What role should
government play in
addressing the key
challenges that PV
inverters face?

NCI’s five-step project approach provided the basis for addressing
NREL’s questions.

Text Box: Introduction Approach
Introduction Approach
Pentagon: Historical Perspective
Historical
Perspective1Future
Performance
and Cost
Estimates2Challenges
for
Achieving
Targets3Addressing
Challenges
for
Achieving
Targets4Government’s
Role in
Addressing
Challenges5Do PV inverters face challenges in
meeting the U.S. DOE’s Solar
Energy Technologies Program’s
targets?
What role should the U.S. DOE
play in addressing the key
challenges that PV inverters face?
Is there a clear understanding and
consensus for addressing key PV
inverter challenges?
What are the
critical cost and
performance
improvement
needs for PV
inverters that
government
should support
to promote PV
market growth?

NCI first collected data on inverter trends for the past 8 years.

Text Box: Introduction Step 1 – Historical Perspective
Introduction Step 1 –Historical Perspective
Pentagon: Historical Perspective
Historical Perspective1
Text Box: Objective
Objective•Provide
performance and
cost information
on typical
inverters used for
U.S. residential
and commercial
buildings, and
central
power/utility
applications.
Tasks•Pricing information and key
performance information for
inverters during the past 3-5 years.
•Key information about product
attributes, such as weight, voltage
range, and sizes of commercial and
residential units.
•Advantages and limitations of past
products.
Approach•Obtain product information
from company Web sites.
•Call the top players (e.g. SMA,
Xantrex, Fronius) to discuss past
performance and cost issues.
•Interview key inverter and
module manufacturers at
European PV conference in
Barcelona to obtain their views
as well as possible reports or
other documentation for review.

NCI conducted interviews with inverter players in Europe and theUnited
States to identify likely cost and performance trends for the next 10 years.

Text Box: Introduction Step 2 – Future Performance and Cost Estimates
Introduction Step 2 –Future Performance and Cost Estimates
Pentagon: Future Performance and Cost Estimates
Future Performance and
Cost Estimates2
Text Box: Objective
Objective•Provide
information on
inverter cost and
performance
trends that are
expected during
the next 10-20
years.
Tasks•Show how inverter prices are likely to
change during the next 10-20 years.
(Include assumptions about market
size driving economies of scale and
learning)
•Discuss likely customer inverter needs
for residential, commercial, and central
inverter applications.
•Show likely changes in inverter
performance during the next 10-20
years.
Approach•Update in-house knowledge
base.
•Call the top players (e.g.
SMA, Xantrex, Fronius) to
discuss past performance
and cost issues.
•Interview key inverter and
module manufacturers at
European PV conference in
Barcelona to obtain their
views as well as possible
reports or other
documentation for review.

The interviews provided information on some of the challenges for
achieving the cost and performance targets.

Text Box: Introduction Step 3 – Challenges for Achieving Targets
Introduction Step 3 –Challenges for Achieving Targets
Pentagon: Challenges for Achieving Targets
Challenges for Achieving
Targets3
Text Box: Objective
Objective•Identify
challenges for
achieving the cost
and performance
targets.
Tasks•Discuss potential barriers for cost and
performance targets for residential,
commercial, and central station
applications.
•Discuss technical, manufacturing,
regulatory, policy, and market
challenges.
Approach•Review literature
•Interview select inverter
manufacturers in the R&D,
marketing, and sales
divisions.
•Interview staff at research
organizations in the United
States, such as SNL; and, in
Europe, such as the
Fraunhofer Institute.

NCI then identified possible ways to address the challenges for
achieving the cost and performance targets.

Text Box: Introduction Step 4 – Addressing Challenges
Introduction Step 4 –Addressing Challenges
Pentagon: Addressing Challenges for Achieving Targets
Addressing Challenges
for Achieving Targets4
Text Box: Objective
Objective•Identify possible
ways to overcome
key cost and
performance
challenges.
Tasks•Identify possible ways to address
inverter challenges during the next 10
years that can help industry achieve its
cost and performance targets.
Approach•Conduct select interviews
with R&D or engineering
staff of select inverter
manufacturers.
•Summarize interview
findings.

NCI then identified activities the U.S. DOE could support to address
PV inverter challenges in achieving cost and performance targets.

Text Box: Introduction Step 5 – Role for U.S. DOE
Introduction Step 5 –Role for U.S. DOE
Pentagon: DOE’s Role in Addressing Challenges
DOE’s Role in Addressing
Challenges5
Text Box: Objective
Objective•Identify possible
ways to overcome
key cost and
performance
challenges.
Tasks•Identify possible ways to address
inverter challenges during the next 10
years that can help industry achieve its
cost and performance targets.
Approach•Conduct select interviews
with R&D or engineering
staff of select inverter
manufacturers.
•Summarize interview
findings.

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5
Bevel: Future Performance and Cost Estimates
Future Performance and Cost Estimates
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6
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3
Bevel: Historical Perspective
Historical Perspective
Bevel: Challenges for Achieving Future Targets
Challenges for Achieving Future Targets
Bevel: Addressing the Challenges
Addressing the Challenges
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2
Bevel: Introduction
Introduction
Text Box: Table of Contents
Table of Contents
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7
Bevel: Suggested Role for Government
Suggested Role for Government
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1
Bevel: Executive Summary
Executive Summary

The U.S. grid-connected market has been strongest in California where
buy-down programs make systems more economically attractive.

Text Box: There has not been a national subsidy program for PV, only a 10% federal investment tax credit on
commercial applicat
•There has not been a national subsidy program for PV, only a 10%federal investment
tax credit on commercial applications and a 5-year accelerated depreciation, so
support has been dependent largely on state programs.
•The recently passed Energy Bill includes $400 million worth of solar incentives (PV
and solar thermal), including a 30% investment tax credit for both residential
homeowners and commercial building owners for the next 2 years. The residential
credit is capped at $2,000 per credit.
•NCI estimates the U.S. grid-connected market to be 51 MW in 2004. California is the
largest market with 37 MW installed in 2004, resulting in a cumulative market of
about 93 MW for grid-connected systems at the end of 2004.
•The most common installation size for residential systems in California is 4-5 kW.
Installations of greater than 10 kW are becoming more common. The California
Energy Commission (CEC) is considering a feed-in tariff (utility buyback rate) for PV.
•In the United States, where grid reliability has been a problem in recent years, the
demand for grid-connected inverters that can also provide backup power from
batteries is higher than in Europe.
Text Box: U.S. Market
U.S. Market
Text Box: Historical Perspective U.S. PV Market » Size and Growth
Historical Perspective U.S. PV Market »Size and Growth

Installation size refers to the size of the PV system, not the size of the individual inverters.

kW shown are for systems installed within the CEC program only.

Installation Size Distribution in CEC Program (kW installed)

Residential and Small Commercial (<30 kW)

kW

2001

2002

2003

2004

0 -< 2.0

419.3

15.1%

798.6

11.1%

779.8

6.5%

532.4

4.3%

2.0 -< 3.0

885.6

32.0%

1,777.1

24.7%

2,595.0

21.8%

2,324.6

18.7%

3.0 -< 5.0

824.7

29.8%

1,964.2

27.3%

3,214.8

27.0%

3,544.6

28.5%

5.0 -< 10.0

605.0

21.8%

2,328.7

32.3%

4,070.0

34.2%

4,193.7

33.8%

10.0 -< 30.0

36.4

1.3%

332.8

4.6%

1,256.2

10.5%

1,821.3

14.7%

TOTAL

2,771.0

100.0%

7,201.4

100.0%

11,915.8

100.0%

12,416.5

100.0%



Residential and Small Commercial (<30 kW) vs. Large Systems

< 30

2,771.0

83.5%

7,201.4

89.4%

11,915.8

92.5%

12,416.5

100.0%

30 +

548.9

16.5%

857.2

10.6%

962.2

7.5%

0.0

0.0%

TOTAL

3,319.9

100.0%

8,058.6

100.0%

12,878.0

100.0%

12,416.5

100.0%



Text Box: CEC data shows the proportion of installations of 3 kW or less is declining, while 10-30 kW
installations are on the
CEC data shows the proportion of installations of 3 kW or less is
declining, while 10-30 kW installations are on the rise.
Text Box: Source: California Energy Commission, 2004.
Source: California Energy Commission, 2004.
Text Box: Historical Perspective U.S. PV Market » Installation Sizes
Historical Perspective U.S. PV Market »Installation Sizes

Installation Size Distribution in NJ (kW installed)

Residential and Small Commercial (<30 kW)

kW

2001

2002

2003

2004

0 -< 2.0

1.5

20.0%

7.4

5.5%

1.4

0.1%

4.0

0.3%

2.0 -< 3.0

2.3

30.7%

32.3

24.2%

41.9

3.4%

14.0

1.0%

3.0 -< 5.0

3.8

50.7%

17.4

13.0%

271.9

21.9%

176.0

12.5%

5.0 -< 10.0

0.0

0.0%

25.8

19.3%

531.7

42.9%

651.0

46.4%

10.0 -< 30.0

0.0

0.0%

50.5

37.9%

392.0

31.6%

559.0

39.8%

TOTAL

7.5

100.0%

133.4

100.0%

1,238.9

100.0%

1,404.0

100.0%



Residential and Small Commercial (<30 kW) vs. Large Systems

< 30

7.5

100.0%

133.4

21.6%

1,238.9

18.3%

1,404.0

9.1%

30 +

0.0

0.0%

485.0

78.4%

5,514.8

81.7%

14,048.0

90.9%

TOTAL

7.5

100.0%

618.4

100.0%

6,753.7

100.0%

15,452.0

100.0%



Text Box: Compared to CEC, data for New Jersey residential and commercial PV installations shows an
even stronger trend toward
Compared to CEC, data for New Jersey residential and commercial PV
installations shows an even stronger trend toward larger installations.
Text Box: Historical Perspective U.S. PV Market » Installation Sizes
Historical Perspective U.S. PV Market »Installation Sizes

Inverter Size Distribution in CEC Program

Installed PV System Capacity (kW)

Size of
inverter(s)
used (kW)

2001

2002

2003

2004

0 -< 2.0

183.9

5.5%

429.8

5.3%

658.8

5.1%

566.5

4.6%

2.0 -< 3.0

1,243.7

37.5%

5,466.2

67.8%

9,905.0

76.9%

9,565.8

77.0%

3.0 -< 5.0

20.0

0.6%

339.8

4.2%

173.0

1.3%

1,216.1

9.8%

5.0 -< 10.0

8.8

0.3%

509.4

6.3%

430.2

3.3%

205.3

1.7%

10.0 -< 30.0

73.6

2.2%

520.9

6.5%

668.5

5.2%

306.0

2.5%

30.0 +

0.0

0.0%

192.8

2.4%

760.5

5.9%

114.3

0.9%

Inverter size
not reported

1,790.0

53.9%

599.7

7.4%

282.0

2.2%

442.6

3.6%

TOTAL

3,319.9

100.0%

8,058.6

100.0%

12,878.0

100.0%

12,416.5

100.0%



Text Box: CEC data shows that inverters in the 2-3 kW range dominate the market (SMA SB 2500). Sharp’s
Sunvista 3500 accounts f
CEC data shows that inverters in the 2-3 kW range dominate the
market (SMA SB 2500). Sharp’s Sunvista 3500 accounts for the recent
growth in the 3-5 kW range.
Text Box: Historical Perspective U.S. PV Market » Inverter Sizes
Historical Perspective U.S. PV Market » Inverter Sizes
Text Box: Source: California Energy Commission, 2004.
Source: California Energy Commission, 2004.
Text Box: Data shown are for systems installed within CEC program only.
Data shown are for systems installed within CEC program only.

Despite modest production volumes, inverters have evolved
significantly since the 1980s through manufacturer innovations and
technology improvements.

1991

The early 1990s saw the first large-scale series
production of PV inverters (SMA PV-WR).



1980s

Inverters were bulky, heavy, difficult to install,
unreliable, and their efficiency was in the 85-90%
range. They were strictly devices for converting DC
to AC.



1995

First PV string inverter (SMA SB 700). Allows
connection of modules in series, modular systems,
higher system efficiency, and reliability. String
inverter becomes most common on the market.



Text Box: Historical Perspective Inverter Features » Evolution 1990-2000
Historical Perspective Inverter Features »Evolution 1990-2000
2000
(1.1kW)
1989
(1.5kW)
Late
1990s
..Basic data-acquisition system, “plug-and-play” installation.
..Transformerless and high frequency (HF) designs reach efficiencies above 95%
..Reliability improves. Warranties (2-5 years) offered.

Along with a trend toward increasing sizes, inverters are becoming
increasingly sophisticated, with added capabilities.

Text Box: Historical Perspective Inverter Features » Recent Developments
Historical Perspective Inverter Features »Recent Developments
Text Box: The latest inverters feature data logging and communication capabilities. Inverter manufacturers
provide the software
•The latest inverters feature data logging and communication capabilities. Inverter
manufacturers provide the software required to process the data sent by the inverter.
–Allows quick diagnostic when the system is not operating properly. It also
allows the user to adjust system parameters for optimal operation.
Text Box: Data logging, communications, and diagnostics
Data logging, communications, and diagnostics
Text Box: A “master” inverter controls the operation of one or two “slave” inverters, such that the slaves
are brought online o
•A “master” inverter controls the operation of one or two “slave”inverters, such that
the slaves are brought online only when the power produced by the modules is
sufficient. In this way, inverters always operate at an optimized power level to achieve
higher system efficiency.
Text Box: Master-Slave Configuration for Improved Efficiency at Partial Load
Master-Slave Configuration for Improved Efficiency at Partial Load
Text Box: Inverter manufacturers have been increasing the size of models meant for residential and small
commercial application
•Inverter manufacturers have been increasing the size of models meant for residential
and small commercial applications. New models are generally above 2 kW in size.
•Many manufacturers report that the typical residential installation size is in the 3-5
kW range, and that 10 kW installations are also becoming more common.
Text Box: Larger Size (> 2 kW)
Larger Size (> 2 kW)

Multi-string inverters allow a single inverter to convert power input
from several module strings, reducing inverter costs for PV systems.

Text Box: Historical Perspective Inverter Features » Recent Developments
Historical Perspective Inverter Features »Recent Developments
Text Box: In many installations, strings of PV modules operate under different conditions, which requires a
separate inverter f
•In many installations, strings of PV modules operate under different conditions, which
requires a separate inverter for each string. Multi-string technology allows multiple
(usually two or three) strings to be connected to a single inverter. So-called multi-string
inverters feature a separate Maximum Power Point Tracker (MPPT) for each string,
ensuring maximum energy yield.
•Examples of differences that can be accommodated with a single multi-string inverter
are:
–Orientation–Shading–Number of modules–Module type or cell type•This feature appears to be an
increasingly important one, as system sizes grow and
there is a need to accommodate modules in different orientations.
•Many popular residential inverter models being used in the United States currently do
not have this feature.
Text Box: Multi-string Capability
Multi-string Capability

Transformerless designs –popular in Germany and Japan –reduce
inverter size, cost, and weight, while improving efficiency.

1. Transformerless inverters are not currently allowed in Spain and Italy. In the United States, the NEC now
allows ungrounded PV arrays, but resistance from the utilities prevents the use of transformerless
inverters.

Text Box: Historical Perspective Inverter Features » Recent Developments
Historical Perspective Inverter Features »Recent Developments
Text Box: The transformer in conventional inverter designs is responsible for losses of around 2% in peak
efficiency and accoun
•The transformer in conventional inverter designs is responsible for losses of around 2% in peak
efficiency and accounts for the larger part of the inverter’s weight. Designs that do away with the
transformer are cheaper, more efficient, and lighter.
•However, transformers also provide automatic protection against DC injection, which protects the
grid in case of system malfunction. “Transformerless” designs feature additional electronics and
control components to provide DC injection protection.
•High frequency (HF) transformers are a compromise between the conventional low frequency (LF)
transformers and transformerless designs. HF transformers are small, lightweight, and provide
electrical isolation.
•Even though manufacturers claim that transformerless inverters can be made as safe as LF designs,
they cannot be installed in some countries1:
..Issues related to galvanic protection are the most important hurdles associated with approval
of their use.
..Manufacturers expect changes in regulations or in utility requirements to take time, so
inverters with transformers will continue to be needed to serve many markets.
Text Box: Transformerless / HF Design
Transformerless / HF Design

Data on production cost are not available for inverters, so price
data must be used as a proxy.

•In the long run, price trends reflect cost trends; but, in the short run, there may be
other dynamics at play that are not related to actual productioncosts.
•Price trends over periods of 10 years or less may not reflect cost trends accurately
and should be analyzed with care and in context.


Source: Refrences 12 and 13

time$
Cost of
productionPriceStability
period“Shakeout”
period
..During stability periods –where profits
grow and new entrants are attracted to the
market –the price trends under-represent
the decrease in production cost.
..During “shakeout” periods –characterized
by fierce competition, mergers,
bankruptcies, and steep price declines –
prices can decrease faster than production
costs.
Text Box: Historical Perspective Inverter Prices » Cost vs. Price
Historical Perspective Inverter Prices »Cost vs. Price

An “average”price per kW is difficult to ascertain for PV inverters.

Text Box: The rated power of the inverter is not the only factor that determines price.
The technology varies considerably from
•The rated power of the inverter is not the only factor that determines price.
..The technology varies considerably from manufacturer to manufacturer, leading
to differences in efficiency, size, weight, reliability, etc. These factors influence
the cost of producing inverters and the price that consumers arewilling to pay.
..Additional features, such as a visual display, data monitoring and storage, and
communication capabilities, can lead to substantial price differences between
inverters of comparable rated power.
•Analysis of inverter price trends over time must take into account the evolution of
inverter features.
..In the past 5-10 years, inverters have evolved significantly. Reliability, ease of
installation, user friendliness, efficiency, size and weight, etc. have all improved
significantly. As a result, a simple analysis of $/kW prices is not representative of
the real improvement in inverters.
•Inverter size has an important impact on cost. For instance, a 3kW inverter is about
50% cheaper than a 1 kW unit on a $/kW basis. So, even within a relatively narrow
size range, a single average $/kW figure inevitably hides large variations.
Text Box: Historical Perspective Inverter Prices » Determining Factors
Historical Perspective Inverter Prices »Determining Factors

Inverter prices reported by SEPA for the TEAM-UP initiative were in
the $1.50/kW to $2.00/kW range for residential applications.1

•From 1996 to 2000, 644 residential installations were put in place, although inverter
price data was not reported for all installations.


Text Box: Historical Perspective Inverter Prices » TEAM-UP residential installations
Historical Perspective Inverter Prices »TEAM-UP residential installations
$0.00$0.50$1.00$1.50$2.00$2.5019961997199819992000YearNumber of
installationskWAverage size
(kW)
199691350.933.86199783309.083.7219986583.051.281999201296.31.472000199183.140.92Source:
Reference 14Inverter Prices for TEAM-UP Residential
Installations1.From to 2001, the Solar Electric Power Association (SEPA) managed TEAM-UP, a cost-
sharing program funded by DOE to promote
grid-tied PV installations.
2.Inverter prices reported for 1997 by SEPA for the TEAM-UP initiative were later determined not to be
reported accurately. The data
was also not available for the entire sample size. Because of limitations in sizes of available inverters,
many were oversized and cost
reported on $/kW basis may not accurately reflect the true selling prices being used at the time.
22

Inverter prices for larger installations (> 70 kW) for TEAM-UP were
generally in the $0.40/kW to $0.80/kW price range.

•From 1996 to 2000, 23 systems ranging from 70 kW to 400 kW were installed.


Source: Refrence 15

Year

Number of
installations

kW

Average size
(kW)

1996

2

317.2

158.60

1997

4

478.4

119.60

1998

7

648.1

92.59

1999

4

393.6

98.40

2000

6

1029.4

171.57



Text Box: Historical Perspective Inverter Prices » TEAM-UP large installations
Historical Perspective Inverter Prices »TEAM-UP large installations
$0.00$0.20$0.40$0.60$0.80$1.0019961997199819992000Inverter Prices for TEAM-UP Commercial
Installations

In 2004, prices for small inverters (<10 kW) in the United States ranged
from $0.67/W to $2.67/W. In 2005, they ranged from $0.48/W to $2.42/W.

Note:

Each point on the chart
represents a particular
model’s average online
retail price at the time of
the survey.

Source: Navigant Consulting Inc., 2005.

Text Box: U.S. Sample Prices - Residential Inverters ($/W)
U.S. Sample Prices -Residential Inverters ($/W)
0.000.501.001.502.002.503.000100020003000400050006000700020042005Price ($/Wac)
Nominal Output Power (Wac)
..Our data indicates that U.S. prices have dropped by roughly 10% in the past year.
Text Box: Historical Perspective Inverter Prices » NCI Survey of U.S. Prices (2004-2005)
Historical Perspective Inverter Prices »NCI Survey of U.S. Prices (2004-2005)

Solarbuzz tracks average inverter prices in Europe and the United States

Text Box: Historical Perspective Inverter Prices » Solarbuzz Data
Historical Perspective Inverter Prices » Solarbuzz Data
0.500.550.600.650.700.750.800.850.900.951.00Jul-03Sep-03Nov-03Jan-04Mar-04May-04Jul-04Sep-04Nov-
04Jan-05Mar-05May-05$/W0.500.550.600.650.700.750.800.850.900.951.00€/WU.S.
EuropeNote:
Solarbuzz reports an average
of all online retail prices,
independent of size.
Text Box: During the past 2 years, prices have fallen by about 13% in Europe.
Contrary to NCI data, Solarbuzz reports stable pr
•During the past 2 years, prices have fallen by about 13% in Europe.
•Contrary to NCI data, Solarbuzz reports stable prices in the United States.

The IEA PVPS program conducted surveys of PV inverters in 1998
and 2002 for U.S., European, and Japanese manufacturers.

Source: Refrence 11

Note:

Each point on the chart represents a
particular model’s average retail price at
the time of the survey.

Text Box: Historical Perspective Inverter Prices » IEA PVPS Data
Historical Perspective Inverter Prices » IEA PVPS Data
Text Box: From 1998 to 2002:
The general price level of inverters fell by about 40%.
Outliers with excessively high prices were
•From 1998 to 2002:
..The general price
level of inverters fell
by about 40%.
..Outliers with
excessively high
prices were
completely
eliminated from the
market.
Text Box: Inverter Prices
Inverter Prices

IEA PVPS data shows that smaller inverters (~1kW) have a volume of
about 15L/kW, whereas larger ones (~5kW) are around 5L/kW.

Source: Refrence 11

Inverter Volumes (2002 data)
Normalized Inverter SystemVolume (liter/kW)
Text Box: Historical Perspective Inverter Dimensions » IEA PVPS Data
Historical Perspective Inverter Dimensions » IEA PVPS Data

IEA PVPS data shows that the weight of transformerless and HF
inverters (~5kg/kW) is 50-75% less than that of LF units.

Source: Refrence 11


Text Box: Historical Perspective Inverter Weight » IEA PVPS Data
Historical Perspective Inverter Weight » IEA PVPS Data
Text Box: Inverter Weights (2002 data)
Inverter Weights (2002 data)

Inverter reliability has an impact on life-cycle cost. Efforts targeting
inverter cost reductions should consider reliability improvements.

0510152025YearsExpensesRevenuePV Project Simplified Cash FlowAssumes expenses on other parts of
the PV system are small.
Inverter replacementsPresent value depends on:
1)Discount rate2)Inverter price reduction rateCash Flow ($)
Text Box: Historical Perspective Inverter Reliability
Historical Perspective Inverter Reliability
Text Box: The inverter accounts for 10-20% of the initial system cost.
Inverters generally need to be replaced every 5-10 years
..The inverter accounts for 10-20% of the
initial system cost.
..Inverters generally need to be replaced
every 5-10 years, whereas modules and
other system components have a life of 25
years or more.
»Investment in a new inverter is required
3-5 times over the life of a PV system.

Discount rate = 5%; Price reduction rate = 5%

Discount rate = 10%; Price reduction rate = 10%

Assuming an initial PV system cost of $8/W:

Note:If one assumes that an inverter can be repaired instead of replaced, this would bring down the NPV
contribution
of the inverter and yield figures lower than the ones shown above.

Text Box: Historical Perspective Inverter Reliability
Historical Perspective Inverter Reliability
Text Box: NCI analysis indicates that the benefits of designing inverters that can operate for 10-15 years or
more before repla
NCI analysis indicates that the benefits of designing inverters that
can operate for 10-15 years or more before replacement are limited.
NPV of life-cycle cost / initial system cost
Inverter replacement intervalInverter cost
(% initial
system)5101525+
10%114.1%105.0%102.2%100%
15%121.2%107.5%103.3%100%
20%128.3%110.1%104.5%100%
Text Box: The benefits of increased reliability must be weighted against the added cost.
The benefits of increased reliability must be weighted against the added cost.
NPV of lifecycle cost ($/W)
9.708.608.26
Inverter replacement intervalInverter cost
(% initial
system)5101525+
10%105.8%101.5%100.5%100%
15%108.6%102.3%100.7%100%
20%111.5%103.1%101.0%100%
NPV of lifecycle cost ($/W)
8.068.188.69

•Based on NPV calculations, the case for developing inverters that can last more than 10
years appears weak.
•The behavior of consumers, who focus mainly on first cost and tend to require short
payback periods, suggests that the discount rate to be used withresidential PV systems is
high. This favors inverter development focused on first cost rather than extended lifetime.


However:

•If consumers who are buying PV systems today are not aware of the future liability
associated with replacing or repairing an inverter, the frustration caused by this
unexpected and significant expense could lead some consumers to abandon their systems,
and it could tarnish the image of PV.
•This is particularly a concern where adoption of PV is based on large rebates: In
California, where consumers sometimes pay as little as 10% of the initial cost of a PV
system, the expense associated with replacing the inverter can be very significant
compared to the first cost of the system.
..Will consumers be eligible for a rebate on replacement inverters?


Text Box: Historical Perspective Inverter Reliability
Historical Perspective Inverter Reliability
Text Box: The economics of long-life inverters are doubtful, but other considerations can change this
conclusion.
The economics of long-life inverters are doubtful, but other
considerations can change this conclusion.

1.Refrence 8.*Note: MTBF isindicative of inverter economic life. It is a calculated number based on
statistically determined reliability
numbers assigned to each component used in a design, and dependson the stress and thermal
environment.
2.Reference 2


Reliability of inverters is still inadequate, but improvements are being
made.

Recent improvements in reliability:

•In recent years, almost every manufacturer of PV inverters has improved their devices’
expected lifetime substantially.2
•A 5-year warranty has become the norm in the industry, whereas 2-year warranties were
most common just a few years ago.
•These longer warranties are somewhat controversial. The manufacturers who offer them
claim that they have gained a better understanding of the causesof inverter failures by
collecting and studying field data, that they have reduced part count, incorporated higher
quality components, and modified product design to lessen component stress where
vulnerabilities were identified. Other manufacturers and industry experts assert that
these warranties are mere marketing tools.
•Manufacturers currently are evaluating offering extended warranties that would be
available for an additional cost. This has become common for other types of appliances,
and is a way for consumers to reduce risk associated with near-term failures.


Text Box: Historical Perspective Inverter Reliability » Recent Developments
Historical Perspective Inverter Reliability »Recent Developments
Text Box: Inverter mean time between failure (MTBF) is reported to be in the range of 5 to 10 years.1* This
short MTBF has a si
Inverter mean time between failure (MTBF) is reported to be in the range
of 5 to 10 years.1*This short MTBF has a significant negative impact on the
competitiveness of PV systems and will inhibit expansion of PV.

•PV Powered (PVP)of Oregon and Sustainable Energy Technologies
(SET)of Canada offer a 10-year warranty, the best available in the
industry.


In the past year, North American manufacturers have introduced
innovative products and set new standards for inverter reliability.

* Note:Other manufacturers point out that different methods of counting parts may be somewhat misleading.

Text Box: Historical Perspective Inverter Reliability » Recent Developments
Historical Perspective Inverter Reliability »Recent Developments
Text Box: PVP and SET inverters have a lower part count than other products available on the market today,
* which increases rel
•PVP and SET inverters have a lower part count than other products available on the
market today,* which increases reliability because:
1.Fewer parts mean fewer failures.
2.Higher-quality parts can be used while still meeting inverter cost targets.
•Both manufacturers use Digital Signal Processing (DSP).
..A DSP chip translates the waveform into digital format, which can then be
processed, evaluated, and modified in very short time periods. As a result, the
inverter can respond quickly to a wide range of situations, which improves
reliability and efficiency.

Bevel: 4
4
Bevel: 5
5
Bevel: Future Performance and Cost Estimates
Future Performance and Cost Estimates
Bevel: 6
6
Bevel: 3
3
Bevel: Historical Perspective
Historical Perspective
Bevel: Challenges for Achieving Future Targets
Challenges for Achieving Future Targets
Bevel: Addressing Challenges
Addressing Challenges
Bevel: 2
2
Bevel: Introduction
Introduction
Text Box: Table of Contents
Table of Contents
Bevel: 7
7
Bevel: Suggested Role for Government
Suggested Role for Government
Bevel: 1
1
Bevel: Executive Summary
Executive Summary

Experience curves model the relationship between cost of production
and production volume, which indicates the level of experience.

Basic Assumption:Cost of production declines by a constant percentage with each doubling of
the total number of units produced. This cost-reduction rate is called the learning rate (LR)and
ranges from 0% to 35% across various technologies.

Text Box: Future Performance Experience Curve » Basic Concept
Future Performance Experience Curve »Basic Concept
02040608010001002003004005006007008009001000LR=0.1LR=0.2LR=0.31101001101001000Cumulative
ProductionCumulative Production (log scale)
Production CostProduction Cost (log scale)

The learning rate for PV modules and balance-of-system is about 20%.
For inverters, however, the learning rate appears significantly lower.

Source: Refrences 12 and 13

1. The study points out that this implies a learning rate in excess of 20% for non-inverter balance-of-system.
The
learning rate for non-inverter BOS is estimated to be 24%.

A comprehensive EU-supported study of prices and production volumes for PV modules
and BOS found that the learning rate in the PV industry is in the 20% -25% range.

..For inverters, the learning rate is significantly lower: approximately 10%.1

•This figure does not give a complete picture of inverter improvements for two reasons:
1.This learning-rate estimate is based on inverter prices, or up-front costs (on a $/kW
basis), rather than life-cycle cost. Therefore, improvements in efficiency and
reliability –which improve inverter life-cycle costs –are not taken into account.
2.Other inverter improvements (e.g. reductions in weight and size,LCD displays,
plug-and-play, multi-string, etc.) are also not taken into account.
•In addition, it must be noted that this result is based on an analysis of prices over the
1995-2002 period, because of insufficient data prior to 1995. As a result, the learning
rate obtained is subject to significant uncertainty, because trends in inverter prices may
not reflect trends in production costs accurately over periods of fewer than 10 years.


Text Box: Future Performance Experience Curve » Results for PV
Future Performance Experience Curve »Results for PV

Data used to estimate the learning ratio for inverters was takenfrom
inverter retail prices in the Netherlands and in Germany (1995-2002).

Note:The Progress Ratio (PR) is related to the Learning Ratio (LR): PR = 1-LR

Source: Refrences 12 and 13

Experience curve for inverter list prices (1995 –2002)
Learning Rate: 7%
Learning Rate: 9%
Text Box: Future Performance Experience Curve » Results for PV
Future Performance Experience Curve »Results for PV

Until recently, the markets for inverters in each country were very
separate, but this situation is changing, particularly in Europe.

•Market boundaries:For PV inverters, differences in regulations between countries have
hindered the emergence of a global market. During the period of 1995-2002, most
manufacturers served only one country.
..The extent of the “Learning System” for inverters was national, which is why the
learning rate was obtained on the basis of installed capacity atthe national level.


•Today, the market for inverters can be broadly segmented among Japan, Europe (mostly
Germany), and the United States. It has internationalized somewhat in recent years, with
several manufacturers serving more than one of the above segments. However, it should
be noted that manufacturers serving multiple markets typically offer different products in
each market.


Text Box: Future Performance Experience Curve » Discussion of Inverter Data
Future Performance Experience Curve »Discussion of Inverter Data
Text Box: Note: Germany and the Netherlands were selected, because the data available for other countries
was insufficient.
Note:Germany and the Netherlands were selected, because the data available
for other countries was insufficient.
Text Box: ? Going forward, the learning system for inverters will become increasingly international,
especially across European
..Going forward, the learning system for inverters will become increasingly international,
especially across European countries. This trend will be less marked in the United States,
because of the level of state control of regulations.

Production volumes can be measured in units or megawatts, but using
megawatts is a more practical alternative.

•Production volumes:The Photex study measured production in MW rather than in number of units. The fact
that
historical data and projections of PV installed capacity are generally available in MW is a strong argument
in support of
this methodology.
•Because average inverter sizes have generally been increasing (from < 2 kW to > 3-5 kW), the learning
rate would be higher,
if it was based on number of units rather than MW. This is because the growth rate as measured in units
produced has
been lower than the growth rate in MW, but the observed prices are obviously not affected by how
production is
measured.


LRunits> LRMW

•If the analysis is done based on units, then LRunitswould have to be applied to projections of units
produced, which would
require making an assumption concerning future trends in inverter sizes.
..If the past trend of increasing inverter sizes is assumed to continue, then the price projections would be
the same
whether the learning curve analysis is based on units or MW.
..If inverter sizes are assumed to stabilize, then the learning-curve analysis based on units would forecast
lower prices.
This is because LRunits> LRMW, while the growth rate in units would be the same as the growthrate in MW.
*


Text Box: Future Performance Experience Curve » Discussion of Inverter Data
Future Performance Experience Curve »Discussion of Inverter Data
Text Box: ? Future trends in inverter sizes cannot be determined with a great degree of certainty. Given the
great number of fa
..Future trends in inverter sizes cannot be determined with a great degree of certainty. Given the
great number of factors that influence inverter prices and the high uncertainty involved in a
learning-curve analysis, adding this extra step to the analysis is not likely to improve results.
Text Box: *NOTE: Inverter prices have been decreasing partly because size has been increasing. Hence, if
inverter sizes are ass
*NOTE:Inverter prices have been decreasing partly because size has been increasing. Hence, if inverter
sizes are assumed to stabilizein the future,
the learning rate inferred from past prices will be too high when applied to future production. This is true
whether the analysis is based on units or
MW, i.e. LRunitsor LRMWwould both be too high. But the fact remains that LRunits>LRMW(they do not
change, because they are based on historical
data and are therefore independent of our assumptions about future size trends), so a learning-curve
analysis based on units would forecast lower
prices than an analysis based on MW. But both analyses would overstate the price reductions, if inverter
sizes are assumed to stabilize in the future.

Using a 20% growth rate in annual sales and a learning rate of 10%,
inverter prices would drop by about 35% in 10 years and 50% in 20 years.

U.S. PV Inverter Prices –Learning Curve Projections

Projections for Various Learning Rates and Industry Growth Rates(2005-2025)

Assumptions:

Installed capacity as of the end of 2004: 163 MW

Sales in 2005: 64 MW

Text Box: Future Performance Experience Curve » Projections for Inverter Prices (U.S.)
Future Performance Experience Curve »Projections for Inverter Prices (U.S.)
Text Box: LR = 5%
LR = 5%LR = 10%LR = 15%
0102030405060708090100200520102015202020250102030405060708090100200520102015202020250102
03040506070809010020052010201520202025% of 2004 Price% of 2004 Price% of 2004
PriceYearYearYearDOE TargetDOE TargetDOE Target
Annual Sales Growth Rate:10%20%30%

Price projections based on world inverter sales yield results that are
nearly identical to the U.S. case.

World PV Inverter Prices –Learning Curve Projections

Projections for Various Learning Rates and Industry Growth Rates(2005-2025)

Assumptions:

Installed capacity as of the end of 2004: 2,080 MW

Sales in 2005: 908 MW

Text Box: Future Performance Experience Curve » Projections for Inverter Prices (World)
Future Performance Experience Curve »Projections for Inverter Prices (World)
0102030405060708090100200520102015202020250102030405060708090100200520102015202020250102
03040506070809010020052010201520202025L = 5%LR = 10%LR = 15%
% of 2004 Price% of 2004 Price% of 2004 PriceYearYearYear
Annual Sales Growth Rate:10%20%30%

Based on NCI analysis of learning-curve rates, we believe 10% is a
reasonable estimate for both the U.S. and international invertermarkets.

Text Box: Future Performance Experience Curve » Discussion of Projections
Future Performance Experience Curve »Discussion of Projections
Text Box: The high degree of similarity between U.S. and world projections is due to the fact that world and
U.S. PV markets ar
•The high degree of similarity between U.S. and world projectionsis due to the fact that
world and U.S. PV markets are both growing at a similar rate: The sales forecast for
2005 represents about 40% of installed capacity for the United States, while the figure is
only slightly higher for the world, at 44%. Should the market growth rates diverge in
the future, inverter price trends may differ more significantly between the U.S. and
world markets.
Text Box: Our central estimate for the learning rate is 10%, which is slightly higher than the 7-9% figure
obtained by the PHOT
•Our central estimate for the learning rate is 10%, which is slightly higher than the 7-9%
figure obtained by the PHOTEX study. We believe the learning rate is likely to go up in
the future for the following reasons:
1.Consolidation: As the inverter market matures, smaller manufacturers will be
rooted out and a limited number of manufacturers will take over larger market
shares. As these manufacturers benefit from increasing volumes, learning effects are
likely to accelerate.
2.Globalization: As manufacturers expand into new markets becoming global
suppliers, they will benefit from larger sales volumes. In addition, having a foothold
in several markets will limit their exposure to unpredictable policy changes, which
should promote investment. The eventual harmonization of standards regarding PV
installations, interconnection, and inverters will help to accelerate this trend.

Our central estimate based on learning-curve projections shows inverter
prices going down by about 42% by 2020.

Text Box: Future Performance Experience Curve » Discussion of Projections
Future Performance Experience Curve »Discussion of Projections
•This assumes a 20% per annum market growth and a 10% learning curve.
•However, additional features and other technology improvements have been added
over time, such as data logging capabilities, communications andcontrols, and others.
Additional features are likely to be added in the future. Therefore, it is difficult to
compare inverter prices over time, as the products are not uniform.
•Therefore, while the DOE goal may appear difficult to achieve onthe basis of typical
learning-curve improvements, it is likely that future products will provide additional
customer benefits.
00.10.20.30.40.50.60.7DOE Goal$1/W$0.65/WBase Price (2004)
Inverter Price in 2020 ($/W)The DOE target for inverter prices is $0.25-0.30/W by 2020.
..If the basis for current inverter prices is taken as
~$1.00/W, which is representative of inverters in the 1-3
kW size range, then the price forecast for 2020 is $0.58/W,
or about twice the DOE target.
..If the basis for current inverter prices is taken as
~$0.65/W, which is representative of inverters in the 3-6
kW size range (XantrexGT 3.0, SMA SB 6000), then the
price forecast for 2020 is $0.38/W, still about 30% higher
than the DOE goal.

Inverter manufacturers have diverging cost expectations, and
projections made in the past have generally been inaccurate.

1.References 12 and 13
2.Refrence 16
3.Reference 2


Text Box: Future Performance Future Prices » Manufacturer Expectations
Future Performance Future Prices »Manufacturer Expectations
Text Box: SMA stated in mid-2004 that it wanted to reduce inverter prices by 50% by the end of 2006.1 The
observed evolution in
•SMAstated in mid-2004 that it wanted to reduce inverter prices by 50% by the end of
2006.1The observed evolution in inverter prices since then suggests that it is highly
unlikely that this objective will be obtained. However, it is interesting to note that SMA
further stated that:
..Cost reductions to less than €250/kW did not seem possible with current technologies.
Break-through technologies that may enable further cost reductions beyond 2010 were
module-integrated inverters, high-frequency converters, and high-voltage converters.
•More recently, SMA has stated that their goal for inverter costswas to bring down the
specific price ($/kW) by 50% every five years.2•Photon Internationalreports that inverter prices have gone
down by 7% from 2004 to
2005 and that most manufacturers expect costs to decrease by 15-25% during the next 5
years3. However, expectations vary across manufacturers:
..Exendisexpects reductions of more than 30% during the next 5 years.
..Sun Powerforesees only slight reductions in cost in the near future and expects
inverter prices to stabilize, at least for the next few years.

Inverter manufacturers do not think that lifetime on the order of 20
years is achievable in the near term…

Text Box: Future Performance Reliability » Manufacturer Expectations
Future Performance Reliability »Manufacturer Expectations
Text Box: Xantrex, Managing Director: “Why make inverters with a longer life when the customer is better
off replacing the inve
•Xantrex, Managing Director: “Why make inverters with a longer life when the customer is better off
replacing the inverter every 10 years or so anyway? The inverters available in 10 years will be better
products with higher efficiency.”
•SMA America, President: “Why focus on higher reliability? Our customers worry only about first-
cost. In any case, it’s more cost-effective to just replace the inverter in 10 years.”
•Sustainable Energy Technologies, Director of Operations: “A 20-year lifetime for PV inverters is at
least10 years away.”
•Mitsubishi: “A 20-plus-year life for inverters is impossible. Some parts of the inverters would need to
be replaced over such an extended period.”
•SMA, Head of Solar:“A 20-year lifetime is not possible.”
•Fronius, Head of Sales (Germany):“Inverter MTBF may reach 12 years by 2015. A 20-year lifetime
can’t be achieved.”
•GE Energyindicated that 20-year life would not be practical without a significant impact oncost. A
15-year life is more reasonable, and that should be reviewed based on life-cycle costs impact.
•Contrary to statements made in a recent Photon International article (April 2005), manufacturers and
other industry experts we spoke to do not believe that capacitorimprovements alone will result in
inverters that can “keep going for more than 20 years.”
Text Box: … and most interviewed by NCI do not see this as a reasonable target.
…and most interviewed by NCI do not see this as a reasonable target.

Next-generation inverters will enhance the competitiveness of PV
through lower cost, higher reliability, and better performance.

1. SMA Sunny Mini Central 8000TL

Text Box: Future Performance Next-Generation Inverters » Needed Improvements
Future Performance Next-Generation Inverters »NeededImprovements
Next-Generation InverterFeatureDescriptionHigher
Efficiency
..Currently, maximum efficiencies are on the order of 95% for U.S.inverters. In Europe,
transformerless designs and innovative topologies are yielding higher efficiencies, with
one model claiming 98%.1Lower Cost..A price target of around $0.2-0.3/W by 2020 has been set for
inverters, which represents
a reduction of 50-75% from current levels. This is most likely to be achieved through
increased production volumes and learning-curve improvements.
Better Reliability..Inverter MTBF is now in the 5-to 10-year range. Ideally, inverters would last as long as
other PV system components (i.e. 25 years), but many question whether such
improvements will ever be achievable at a reasonable cost. In the near-to medium-term,
an MTBF of >10 years is likely to be achievable through improving quality control, better
heat dissipation, and reducing complexity.
Advanced
Communication
Capabilities
..Today, inverters can record and relay information using manufacturer specific
protocols. Next-generation units should use a universal communication standard to
relay more comprehensive system information, enabling advanced diagnostic features
and communication with the utility to support grid stability.
DG Inverter ..An inverter that can convert DC input from various DG sources (fuel cells, PV, small
wind) will benefit from economies of scale, and new technology (e.g., SiC), resulting in
cheaper, more reliable products for many DG applications.

Achieving the targeted improvements of lower cost and higher
reliability for inverters is not a foregone conclusion for the industry.

•Based on learning-curve forecasts, the targeted cost reductions for 2020 will not be
achieved with current market growth and learning-rate levels.
..Significant uncertainty exists around the potential for future market growth to
exceed current levels for an extended period of time.
..Additional cost reductions will require an acceleration of learning effects.
..Inverter prices have been dropping by about 10% with every doubling of
cumulative production, compared to 20% for PV modules.
•Reliability and life issues for inverters have the potential to damage the reputation of
the industry and long-term adoption of PV.
..Because of market demands, manufacturers today are focused on lowering first-cost
over improving reliability.
..Reliability and life improvements may not be achieved with consistency across the
industry.


Text Box: Future Performance Summary
Future Performance Summary
Text Box: ? In order to increase the probability of achieving the goals of industry, which are necessary for
the PV market to b
..In order to increase the probability of achieving the goals of industry, which are
necessary for the PV market to become sustainable over the long term, ongoing
government support for inverter R&D is likely to be necessary.

Bevel: 4
4
Bevel: 5
5
Bevel: Future Performance and Cost Estimates
Future Performance and Cost Estimates
Bevel: 6
6
Bevel: 3
3
Bevel: Historical Perspective
Historical Perspective
Bevel: Challenges for Achieving Future Targets
Challenges for Achieving Future Targets
Bevel: Addressing the Challenges
Addressing the Challenges
Bevel: 2
2
Bevel: Introduction
Introduction
Text Box: Table of Contents
Table of Contents
Bevel: 7
7
Bevel: Suggested Role for Government
Suggested Role for Government
Bevel: 1
1
Bevel: Executive Summary
Executive Summary

The PV inverter industry faces some significant challenges to achieving
its longer-term targets for cost and performance improvements.

Text Box: Challenges Overview
Challenges Overview
Text Box: Research shows that inverters have a slower learning curve than the PV module industry, which
implies that cost and p
•Research shows that inverters have a slower learning curve than the PV module industry, which
implies that cost and performance improvements for inverters will lag behind PV modules.
•Historical data shows that inverter costs have been falling approximately 5-10% a year since 1999.
–We anticipate this cost reduction curve to continue into the future, assuming the industry grows
as forecast.
•Manufacturers generally feel that designing inverters for longerthan 15 years is not practical and, in
general, is not necessary. Most manufacturers say that the more important issue for consumers is
lower first-cost.
–A 20-year MTBF is viewed as not possible and may not be an appropriate target.
•Inconsistent national and state regulatory standards have hurt PV inverter manufacturers’ ability to
grow in the past, limiting many to focus on regional markets.
–This issue is gradually improving; but, in the United States, differences in requirements for states
will likely continue to impede cost benefits associated with larger market volumes, at least for
the next few years.
•On the other hand, given their small size and relatively low level of sophistication, PV inverter
manufacturers may benefit tremendously from small improvements to design and manufacturing
(e.g. low-hanging fruit for cost and performance improvements).
–Improvement in components (such as capacitors), the trend to high-frequency transformers, or
transformerless designs are examples of opportunities that will contribute to cost and

Many of the challenges for PV inverters are a result of low-volume
manufacturing and an inconsistent regulatory environment.

Text Box: Challenges Overview
Challenges Overview
Manufacturing1.Inadequate product-improvement processes2.Lack of training3.Products rushed to market
too quickly4.Lack of good quality-control processes5.Lack of investment in sophisticated testing and
manufacturing equipment
6.Components purchased in small quantitiesDesign/Technology7.Advanced semiconductor devices for
switching needed (e.g. SiC devices)
8.Need to improve efficiency9.Limited experimentation with alternative inverter topologies10.Capacitors
available on the market are not well-suited to PV inverter applications11.Lack of sophistication in inverter
designs (e.g. leveraging synergistic applications)
Regulatory12.Regulations differ across PV markets13.Regulatory complexity generally increases cost14.U.
S. grid-interconnection regulations are a heavy burden on inverter manufacturers15.U.S. requirements for
PV installation increase costs substantially16.Utility resistance to ungrounded systemsPolicy17.Few states
have adequate incentives to promote PV market growth18.Changing policies hamper long-term investment
decisions

Many manufacturers are small startups that lack the internal processes
needed for quality control of product development and manufacturing.

Text Box: Challenges Manufacturing Issues » Inadequate Internal Processes
Challenges Manufacturing Issues » Inadequate Internal Processes
1. Inadequate
product
improvement
processes
..Internal processes that provide the discipline, resources, and commitment
needed for continuous product improvement are lacking among manysmall
inverter manufacturers.
2. Lack of
training
..Inverter manufacturers typically have a small workforce, where employees are
asked to perform several different tasks, often without adequatetraining.
3. Products
rushed to
market
..The pressure to ship as soon as possible leads manufacturers to produce poorly
written and insufficient documentation, leading to low installer/customer
satisfaction and expensive customer support.
4. Lack of good
quality-
control
processes
..Due to limited resources, inverter manufacturers compromise quality control:
–Inspections that can identify problems early in the manufacturing process are
not carried out properly.
–Proven methods such as “Highly Accelerated Life Tests”(HALT) are often
overlooked or not used.
–“Failure” documentation is inadequate or nonexistent. Inverter
manufacturers typically have little information on failures of their units in the
field or during testing, making it difficult to identify problemtrends and take
corrective action.
..Inadequate quality control leads to reliability problems and ultimately imposes
additional costs on inverter manufacturers.

Low production volumes make it impossible for manufacturers to take
advantage of mass-production technologies and volume discounts.

Text Box: Challenges Manufacturing Issues » Small Production Volumes
Challenges Manufacturing Issues »Small Production Volumes
5. Lack of
investment in
sophisticated
testing and
manufacturing
equipment
..Most inverter manufacturers are small companies–They cannot afford expensive testing equipment based
on their modest sales
volume.
–Low production volumes cannot justify the investment needed for an
automated production line, and they do not have the needed expertise.
..Inverter manufacturers cannot make investments that would greatlyimprove
product quality, because their sales volumes don’t currently justify it. Proven
methods to detect design flaws such as “Highly Accelerated Life Tests” (HALT) are
not used.
6. Components
purchased in
small quantities
..Most inverter manufacturers purchase components in small quantities, due to
modest sales volume:
–They cannot benefit from discounts offered on large orders and better supply-
chain management–With each new order for a given component, inverter manufacturers often
purchase from different suppliers, depending on where they can find the best
price. This results in wide component variations and problems with the final
product.
–Inverter manufacturers typically do not audit their suppliers for quality control.
..Purchasing components in small quantities leads to higher cost and lower quality –
and impacts reliability.

Components available on the market today do not adequately meet the
technical requirements of the inverters.

Text Box: Challenges Design/Technical Issues » Component Limitations
Challenges Design/Technical Issues »Component Limitations
7. Advanced
semiconductor
devices needed
for switching. (e.g.
SiC devices)
..The various switching devices used in inverters to convert DC toAC current
are another weak point for inverter reliability.
..There are technologies (e.g. SiC switches and integrated circuits) that show
promise for better performance, but inverter manufacturers have little weight
in influencing the direction of R&D and most have limited internal R&D
capabilities in this area.
..Switch reliability is currently inadequate for PV inverters andis a source of
heat generation. New developments (such as SiC) are a power
electronics/semiconductor industry issue, and inverter manufacturers will
have little influence in directing research in this industry.

Lack of resources and design experience hampers inverter productdesign and development improvements.

Text Box: Challenges Design/Technical Issues » Design and Testing Standards
Challenges Design/Technical Issues » Design and Testing Standards
..Converting DC to AC current can be done
using a variety of approaches. The various
designs that inverter manufacturers
incorporate in their inverters to accomplish
this task are known as “topologies.”
..Various topologies yield different inverter
performances in terms of reliability, efficiency,
and cost. While there is generally a trade-off
between these three objectives, some
topologies are simply better than others and
can improve inverters in every respect.
..Inverter manufacturers do not have the resources to experiment with topologies
extensively, so potential inverter improvements may be lost.
9. Limited
experimentation
with inverter
topologiesReliabilityEfficiencyCostReliabilityEfficiencyCost
..Maximum efficiencies are typically near 95% for U.S. inverters, but manufacturers
do not have consistent methods for rating inverters and can choose any point over
the load curve for quoting the rating.
..Consumers do not have an easy way to compare inverters based on efficiency.
..Certification processes could provide standard test methods forrating efficiency.
Design improvements and elimination of transformers could improve efficiencies by
2% or more.
8. Need to improve
efficiency and the
standards for
ratings11. The CEC recently adopted and is using a major portion of Sandia's Test Protocol for Certification
of Inverters. Several states are now accepting
California's published numbers. Still, more needs to be done for features such as MPPT.

Component limitations and lack of design experience hampers
inverter product design and development.

Text Box: Challenges Design/Technical Issues » Components Limitations
Challenges Design/Technical Issues » Components Limitations
10. Capacitors
available on
the market not
suited for PV
inverter
applications.
..Capacitors are often cited as the most severe reliability problem for inverters.
They are extremely sensitive to temperature (electrolytic capacitors), and one
manufacturer reports that an increase of even 10°C can halve capacitor lifetime
(Heliotronics, President, January 2005).
..There are capacitor technologies that show promise for better performance in
PV inverters, but R&D in the capacitor industry is limited
..The capacitor industry is not responsive to PV inverter needs, because PV
inverters account for a small fraction of capacitors sold.
..Capacitor reliability is currently inadequate for PV inverters,and there is little
that inverter manufacturers can do to influence the capacitor industry other
than design around the problem, which impacts cost.
11. Lack of
sophistication
in inverter
designs
..Engineers from other, more mature industries where power electronics are used
have commented that inverter designs are unsophisticated and could often be
improved with some fairly easy fixes (Sun Power, North American Manager,
June 2005).
..Many PV inverter manufacturers lack knowledge or broader experience in
power electronics design.

Lack of an international standard creates regional markets for inverters.
In the U.S., regulations are particularly burdensome for manufacturers.

Text Box: Challenges Regulatory Issues » Inconsistent Requirements and Complexity
Challenges Regulatory Issues » Inconsistent Requirements and Complexity
12. Regulations
differ across PV
markets
..Regulations for grid-connected PV inverters vary across countries. In Europe,
requirements across some countries (e.g. Germany, the Netherlands,
Switzerland) vary only slightly, and manufacturers are able to use the same
inverter models to reach these markets.
..Requirements are most stringent in the United States. International
manufacturers who want to serve this market need to design models
specifically for the United States in order to meet regulations.
..This lack of uniformity creates regional markets, making it extremely difficult
for manufacturers to create a global product (as with modules). By preventing
standardization across markets, potential economies of scale arelost.
13. Regulatory
complexity
increases cost
..Regulatory differences between states or countries require product
modifications and specialization, which increases costs for manufacturers.
..Different safety requirements, interconnection, or testing requirements
increase the cost for manufacturers for selling their products in different
markets.
..Product lines vary by market, and some companies choose to focus on specific
states and not others. These issues lead to higher prices in allmarkets.

Requirements for grid connection vary significantly in spite of UL and
IEEE standards that are expensive for manufacturers to meet.

Text Box: Challenges Regulatory Issues » Requirements for Grid Connection
Challenges Regulatory Issues » Requirements for Grid Connection
14. U.S. grid-
connection
regulations are a
heavy burden on
inverter
manufacturers
..U.S. manufacturers face confusing regulations.
–In 2005, UL 1741 and IEEE 1547 have apparently been consolidatedin a
way that should help resolve some of the confusion around compliance
with these two standards. Ongoing changes to the requirements ofthese
standards is likely to continue to create challenges for manufacturers.
–Acquiring the UL 1741 standard costs nearly $100K, a substantialamount
for small players; and modifications typically require additional testing,
which is a barrier to making improvements.
–Utilities can also adopt their own standards, adding to the complexity.
..UL standards are a damper on innovation, because product improvements
require new testing for modest changes to designs. Utilities andlocal
government can also require their own standards, which increasescost.

Inverter and installation costs are significantly higher in the U.S., driven
by complex requirements and local codes that still requiring grounding.

Text Box: Challenges Regulatory Issues » System Configuration and Grounding
Challenges Regulatory Issues » System Configuration and Grounding
15. U.S.
requirements for
PV installations
increase costs
substantially
..Manufacturers who sell PV inverters in European markets –and in the United
States –report that installation costs are substantially higher in the United States.
–The installed cost of a 5 kW system is about €4.2 –5.0/W in Germany, as
opposed to $6.50 –9.00/W in the United States (Head of
Solar Electronics Division, Fronius, January 2005)
–The cost of installation of a 5 kW system is about €700/kW ($833/kW) in
Germany, as opposed to $1,400/kW in the U.S.
..One of the areas of higher cost in the United States is related to the requirements
for externally accessible AC disconnects and conduits for DC cabling.
..Roughly speaking, installation costs for PV in the United States are nearly twice
that of Germany.
16. Utility and local
resistance to
ungrounded
systems
..Ungrounded PV array installations are allowed by the 2005 National Electric
Code, which means that transformerless inverters could now be used in the U.S.
..However, it is expected that these systems may be difficult for U.S. inspectors
and regulators to accept without substantial additional work on local codes and
standards.
..Resistance to transformerless designs impacts opportunities for significant
inverter improvements: higher efficiency, lower weight, and lower cost.

PV market growth is restricted to a handful of states, limiting prospects
for inverter manufacturers and hampering investment.

Text Box: Challenges Policy Issues » Fragmentation and Inconsistency
Challenges Policy Issues » Fragmentation and Inconsistency
17. Few states have
adequate
incentives to
promote PV
market growth
..Several states have very good incentives for PV (e.g. Calif., N.Y., N.J.), but many
states in areas such the Southeast have no buy-down programs or other
incentives to stimulate installations of PV.
..Where incentives are inadequate, the PV market will see very limited growth,
and potential economies of scale in the United States for inverter manufacturers
will remain untapped.
18. Changing
policies hamper
investment
..Major investment on the part of inverter manufacturers depends on a high level
of confidence in future income streams.
..Uncertain or changing incentives for PV create the wrong kind ofincentives for
manufacturers, who respond by putting their product on the market as quickly
as possible, without investing in lengthy product development orsophisticated
assembly and testing equipment.
..Without stable PV support policies, inverter manufacturers will be unableto
make substantial investments to improve their product.

The majority of challenges faced by PV inverter manufacturers can be
traced back to low production volumes.

Text Box: Challenges Low Production Volumes
Challenges Low Production Volumes
Text Box: “Economies of scale will create a downward pressure on PV inverter costs.”
Sun Power, North American Manager, June 20
“Economies of scale will create a
downward pressure on PV inverter
costs.”
Sun Power, North American Manager,
June 2005“Our costs have gone down 50% due
to volume. Volume is the only cost
driver.”
SolarMax, Managing Director, June 2005“Sales volume in each market
will drive the price of inverters.”
Siemens, June 2005“SMA believes that cost
reductions will be a combination
of new designs, new topologies,
less components, and higher
quantities.”
SMA, Head of Solar Division, June 2005
Text Box: There does not a appear to be a “silver bullet” technology on the horizon that could cause a major
drop in inverter c
..There does not a appear to be a “silver bullet” technology on the horizon that
could cause a major drop in inverter cost.
..The industry anticipates incremental cost and performance improvements for
the foreseeable future.

The PV inverter supplier base is composed of a few big companieswith considerable resources and many
smaller players (others) who
are more likely to benefit from government programs.

Text Box: Challenges Market Share of Inverter Manufacturers
Challenges Market Share of Inverter Manufacturers
SMA41%
Xantrex19%
Sharp13%
Siemens6%
Outback6%
PV
Powered6%
Others 3%
Fronius6%
U.S. Inverter Market Distribution
(% KW Sold in 2004)
Source: Navigant Consulting Analysis, August 2005
SMA42%
Fronius16%
Studer11%
Siemens5%
Mastervolt5%
Philips5%
Kaco5%
Sputnik5%
Others1%
Xantrex5%
European Inverter Market Distribution(% of KW Sold in 2004)

NCI’s assessment is that there is an important role for government in
the support of PV inverter improvements for the next several years.

•In general, larger companies in the PV inverter business view the role of government in providing
assistance (via programs to reduce cost and increase reliability) as being less critical to their success
and the long-term future of the industry.
—Most larger companies NCI spoke to believe that increasing salesvolume is the single largest
factor that will lead to lower cost and higher reliability for PV inverters.
•Despite the views of larger companies, introducing a new inverter product has proven to be a risky
venture for some large companies. For example:
—Xantrex experienced significant problems with their early PV inverters and ended up losing
market share to new European market entrants.
—Philips entered the PV inverter market in Europe, only to exit afew years later after experiencing
significant technical problems with their first product.
•The PV market will be in a critcal growth phase during the next5-10 years, continuing to require
significant policy and market support to achieve the overall cost and performance required for a
sustainable market.
•If small manufacturers have more dificulty meeting the reliability requirements of the market and
cannot afford to provide adequate after-sales service, it could hurt the PV industry as a whole
(inadequately performing inverters will hurt the industry).
•While some consolidation in the inverter business should be expected, the benefits of competition and
innovation provided by the smaller companies are likely to be important to the industry at its current,
early stage of development.


Text Box: Challenges Conclusion
Challenges Conclusion

Bevel: 4
4
Bevel: 5
5
Bevel: Future Performance and Cost Estimates
Future Performance and Cost Estimates
Bevel: 6
6
Bevel: 3
3
Bevel: Historical Perspective
Historical Perspective
Bevel: Challenges for Achieving Future Targets
Challenges for Achieving Future Targets
Bevel: Addressing the Challenges
Addressing the Challenges
Bevel: 2
2
Bevel: Introduction
Introduction
Text Box: Table of Contents
Table of Contents
Bevel: 7
7
Bevel: Suggested Role for Government
Suggested Role for Government
Bevel: 1
1
Bevel: Executive Summary
Executive Summary

Apart from influencing standards and increasing market volume, inverter
gains will come from addressing design/manufacturing challenges.

Text Box: Addressing the Challenges Overview
Addressing the Challenges Overview
Challenge Addressing the Challenge (Industry Need)
Manufacturing/Testing1.Inadequate product improvement processes2.Lack of training3.Products rushed to
market too quickly4.Lack of good quality-control processes5.Lack of investment in sophisticated testing and
manufacturing equipment
6.Components purchased in small quantities
..Assistance for inverter manufacturers with information and
process improvement techniques from other industries
..Better understanding of failure causes
..Training and support in quality management
..Standard testing methods to measure and quote efficiency
..Assistance with HALT and HASS methods and techniques for
lowering risk associated with new product introduction
..Consistent information on component design characteristicsTechnology/
Design7.Advanced semiconductor devices for switching needed
(e.g. SiC diodes)
8.Need to improve efficiency9.Limited experimentation with alternative inverter
topologies10.Capacitors available on the market are not well-suited to
PV inverter applications11.Lack of sophistication in inverter designs12.Regulations differ across PV
markets13.Regulatory complexity generally increases cost14.U.S. grid-interconnection regulations are a
heavy burden
on inverter manufacturers15.U.S. requirements for PV installation increase costs
substantially16.Utility resistance to ungrounded systemsRegulatory17.Few states have adequate incentives
to promote PV
market growth18.Changing policies hamper investment
..Development of advanced switching, capacitor, and other
component technologies for PV and DER inverters
..Modeling tools for experimentation with alternative topologies,
thermal management techniques, and new designs
..Support design of alternative inverter topologies to simplify and
reduce cost of inverters
..Modular designs that would allow lower-cost, interchangeable
components for multiple applications
..Development of appropriate standards across the industry
..Harmonization of regulatory requirements
..Simplification and standardization of interconnection
requirements
..Studies and assessments of options for ungrounded designs,
safety issues, and a broader understanding of the implicationsPolicy..Long-term programs for national
incentives for PV
..Policy that supports the PV industry broadly, which will also
support the inverter industry

Some manufacturers can benefit from assistance in performing some of
the tasks they cannot do, due to their small size and limited resources.

Text Box: Addressing the Challenges Assistance for Inverter Manufacturers
Addressing the Challenges Assistance for Inverter Manufacturers
Inverter Manufacturing and TestingProcess
Improvement
Techniques and
Training
..General support in understanding process-improvement techniques from
other industries (semiconductors, electronics, etc…) to reduce
manufacturing cost.
..Training and support in quality-control techniques used in other high-
volume manufacturing industries (semiconductors, electronics).
Failure
Documentation
..Development of a database to document inverter failures in the field.
Analysis of this database would allow inverter manufacturers to identify
failure modes and correct their designs to improve reliability.
Testing Support –
Performance, HALT
and HASS
..Assist manufacturers by providing support for testing inverters,e.g. IR
imaging for thermal management testing, highly accelerated life tests to
identify weaknesses, HALT and HASS, etc.
..Assistance in developing methods and protocols for testing and
specifying inverter efficiency.
Component Testing
and Documentation
..Test components (e.g. capacitors) to measure their characteristics and rate
their performance –and document the results. There is a great degree of
variation between components available on the market, and this
documentation would allow inverter manufacturers to select the best
available components to incorporate into their products.

Many potential inverter technology and design improvements have
been identified.

1. Inverters that can be used for multiple distributed generation energy sources are referred to as distributed
generation (DG) or distributed energy resource (DER) inverters.

Text Box: Addressing the Challenges Assistance with Technology and Design
Addressing the Challenges Assistance with Technology and Design
New Inverter Technology and Design (1 of 3)
DER inverters1..Inverters used for a variety of DER applications could be produced in greater
quantities, allowing manufacturers to benefit from economies of scale.
..The challenge for PV inverter manufacturers is to understand therequirements of other DER applications
and design inverters suitable for
other applications.
Note:Sustainable Energy Technologies has already designed a PV inverter
that relies on essentially the same design as its fuel cell inverter.
Modeling..Develop and provide modeling tools to enable manufacturers to explore
various inverter designs.
..Develop models for environmental conditions and operational requirements
to help inverter designers understand operational requirementsInnovative
Topologies
..Innovative topologies can reduce capacitor requirements and alleviate
thermal management problems that lead to premature failure of internal
components –but developing new topologies takes time and money.
Installation and
Connection Features
..Connectors have been a reliability issue for inverters for a long time. Work is
needed to simplify, standardize, and improve inverter connectors.

Many potential inverter technology improvements have been
identified (continued).

Text Box: Addressing the Challenges Assistance with Technology and Design
Addressing the Challenges Assistance with Technology and Design
New Inverter Technology and Design (2 of 3)
Circuit Integration..Interconnections between internal inverter components are a weakpoint
for reliability. Integration of functions within imbedded circuits reduces
the number of interconnections. R&D is needed to develop this concept
and bring it to maturity.
Thermal
Management
..Thermal management is a major reliability issue for inverters, because
many components are highly sensitive to temperature. Better thermal
modeling tools are needed to allow manufacturers to research innovative
thermal management strategies.
Modular Design..Modular construction of inverters would reduce costs by standardizing
internal functional elements of inverters. This is an interesting concept
that could benefit from further study.
Note:Modularity may cause listing difficulties with UL.
Replaceable
Capacitors
..To cope with the limited life of capacitors, it has been suggested that
inverters be designed such that capacitors may be easily replaced. The
cost-effectiveness of this approach needs to be assessed.

Inverter manufacturers need cheaper, more reliable components tomake less expensive, more reliable
inverters.

Text Box: Addressing the Challenges Advanced Inverter Components
Addressing the Challenges Advanced Inverter Components
New Inverter Technology and Design (3 of 3) -Advanced ComponentsCapacitors..Inverter manufacturers
frequently state that the capacitors available today
are inadequate. Specifically, manufacturers need twice the life and half the
cost of today’s capacitors.
..R&D is needed to develop improved capacitors, but the PV inverter
industry does not have the resources to carry out this R&D or influence
the capacitor industry, due to the relatively low volumes as compared to
other electronics applications.
Switches..Switches based on SiC hold the promise of better performance: They can
tolerate higher temperatures, can handle very high voltages, they have
low resistance, and can operate at high frequency –which translates into
inverter improvements in weight, size, cost, reliability, and efficiency.
..Commercial applications of SiC are currently limited, due to product
immaturity and high cost.
Transient Surge
Devices
..Research in TSDs is currently minimal, but improvements are needed for
both DC and AC circuits.

Manufacturers need regulatory standards that are clear and uniform
across markets –and not constantly changing.

Text Box: Addressing the Challenges Assistance with Regulatory Standards
Addressing the Challenges Assistance with Regulatory Standards
Text Box: 1. The CEC recently adopted and is using a major portion of Sandia's Test Protocol for Certification
of Inverters.
Regulatory AssistanceHarmonization..Push for harmonization of the various standards that regulate grid-
connection of PV inverters and other DER.
Reduce Burden on
Manufacturers
..Increase participation of manufacturers in development of standards by
subsidizing cost of attending meetings.
..Subsidize cost of acquiring standards.
Acceptance of
Ungrounded Arrays
..Address utility misgivings regarding safety concerns on ungrounded PV
arrays and transformerless inverters. Experience from Japan and Europe
needs to be transferred to the United States.
Communications
Standard
..A standard for communicating DG system information is needed for:
1.Remote monitoring and system diagnostics of inverters using a single
software platform.
2.Efficient communication between DG inverters and the utility grid to
minimize DG interruptions and improve grid stability.
Note:Efforts underway at IEEE and IEC will address this need.
Standard Metrics for
Inverter
Performance
..There are no established methods for rating inverter performancethat
consumers and installers can use to compare inverters (e.g. efficiency can
be reported in any number of ways). This would promote transparency in
the market and favor better inverters while rooting out laggards.11. The CEC recently adopted and is using
a major portion of Sandia's Test Protocol for Certification of Inverters.

One of the most important challenges facing the industry is the need for
long-term, consistent policy to support market development on a
national basis.

Text Box: Addressing the Challenges Assistance with PV Policy
Addressing the Challenges Assistance with PV Policy
Policy AssistanceLong-Term,
Consistent PV
Policy Support
..The U.S. policies for support of PV are currently divided between federal,
state, and local programs. While some programs are year-to-year, others
are multiyear programs to meet PV installation goals.
..Long-term support to programs to build the market for PV consistently,
without stops and starts, will help the industry maintain and grow sales
volumes in a way that will allow continual cost reduction as well as
reliability and performance improvement. Because market volume is the
most important driver in achieving goals of the industry, this area is one
of the most critical to the industry. These policies are important for PV as a
whole, not just for inverters.

Bevel: 4
4
Bevel: 5
5
Bevel: Future Performance and Cost Estimates
Future Performance and Cost Estimates
Bevel: 6
6
Bevel: 3
3
Bevel: Historical Perspective
Historical Perspective
Bevel: Challenges for Achieving Future Targets
Challenges for Achieving Future Targets
Bevel: Addressing Challenges
Addressing Challenges
Bevel: 2
2
Bevel: Introduction
Introduction
Text Box: Table of Contents
Table of Contents
Bevel: 7
7
Bevel: Suggested Role for Government
Suggested Role for Government
Bevel: 1
1
Bevel: Executive Summary
Executive Summary

Long-term cost reduction and performance improvements will benefit
greatly from the ongoing support of additional government programs.

Text Box: Suggested Role for Government Overview
Suggested Role for Government Overview
Text Box: Inverter testing at Sandia National Labs is extremely valuable to the industry, and continued
support of development
•Inverter testing at Sandia National Labs is extremely valuable to the industry, and continued
support of development of testing protocols is important to the industry.
•Documentation of failure analysis in the industry is not conducted uniformly. A possible role
for government would be in collecting and documenting inverter failures to share with the
industry.
•Modeling tools would be helpful to manufacturers, but developingaccurate models is
challenging. An assessment of issues and needs related to modeling would be appropriate
before embarking on new modeling efforts.
•The HRII program is generally considered to have been successful. Follow-on public-private
R&D partnerships such as this should receive government support.
•Cost and efficiency benefits of tranformerless inverters are understood. Studies on the pros
and cons of tranformerless inverters as a means of educating inspectors and regulators would
be beneficial.
•Analysis of the interaction of the various federal, state, and municipal support programs will
be increasingly important to future industry growth needed for long-term success.

Several issues identified are common to all DER inverters and could
be addressed as part of crosscutting research programs.

Text Box: Suggested Role for Government Overview
Suggested Role for Government Overview
Text Box: Comprehensive information on inverter components (capacitors, electrical connectors, power
semiconductors, etc.) and
•Comprehensive information on inverter components (capacitors, electrical connectors,
power semiconductors, etc.) and options would assist manufacturers in identifying the
best products.
•Innovative inverter topologies have been suggested to provide many benefits. A role
for government may be to support experimental topologies as a means of advancing
the industry.
•Manufacturers would benefit from understanding the costs and benefits of HALT and
HASS testing programs. Government could assist by providing general guidelines and
experience from other industries.

Government’s most important role will continue to be in providing
studies and information to facilitate design and product improvements.

Text Box: Suggested Role for Government Overview
Suggested Role for Government Overview
Addressing the Challenge (Industry Need)Role for GovernmentManufacturing/Testing
..Assistance for inverter manufacturers with information and
process improvement techniques from other industries
..Better understanding of failure causes
..Training and support in quality management
..Standard testing methods to measure and quote efficiency
..Assistance with HALT and HASS methods and techniques for
lowering risk associated with new product introduction
..Consistent information on component design characteristics
..Government facilities can provide manufacturers with top-
class inverter testing, as well as testing methodologies for
establishing ratings and efficiencies
..Provide access to training and quality management
capabilities to support companies developing new products
..Provide training and information on process improvement
techniques from other industries
..Provide support to study inverter field performance to
provide better information on causes of inverter failure
..Studies on HALT and HASS testing methods for invertersTechnology/
Design
..Development of advanced switching, capacitor and other
component technologies for PV and DER inverters
..Modeling tools for experimentation with alternative
topologies, thermal management techniques, and new designs
..Support design of alternative inverter topologies to simplify
and reduce cost of inverters
..Modular designs would allow lower cost, interchangeable
components for multiple applications
..Develop appropriate standards across the industry
..Harmonization of regulatory requirements
..Simplification and standardization of interconnection
requirements
..Studies and assessments of options for ungrounded designs,
safety issues, and a broader understanding of the implicationsRegulatory
..Long-term programs for national incentives for PV.
..Policy that supports the PV industry broadly, which will also
support the inverter industry
..Government can provide private-public R&D funding to
support the development of new inverter technology to
support DG needs more broadly
..Funding assistance to study alternative inverter topologies
that significantly lower cost, and improve reliability or
efficiency
..Provide support for inverter modeling capabilities to support
design work (e.g. thermal management, etc…)
..Assist the industry by providing detailed information on
regulatory requirements and variations across the U.S.
..Support studies that identify relationships between
regulatory requirements and design implications
..Support studies and analysis of safety issues, and pros and
cons of ungrounded systemsPolicy..Conduct analysis of alternative policy approaches to gain a
better understanding of the impact of program design on
market growth

Inverter testing at Sandia National Laboratories helps manufacturers
experiment with innovative designs and improve their product.

Text Box: Suggested Role for Government Inverter Testing
Suggested Role for GovernmentInverter Testing
Text Box: Inverter Testing
Benchmarking tests to evaluate inverters against manufacturer specifications. Manufacturers generall
Inverter Testing
..Benchmarking teststo evaluate inverters against manufacturer specifications. Manufacturers
generally agree that a comprehensive program of inverter testingand performance reporting would
be very valuable to the industry.
..Development testingprotocols to assist manufacturers in testing new inverter models.
..Utility compatibility and islanding tests. This type of testing provides manufacturers with
information on their inverters’ ability to meet UL 1741 requirements. Various utilities also request
system-specific tests to be performed to understand the effect of PV inverters on their grid. Debate
exists regarding the value of this, but it will remain a requirement.
..Temperature evaluations. These tests allow manufacturers to study temperature issues and test
various strategies for thermal management, which are critical for product reliability.
Text Box: Verification, validation, and characterization is extremely valuable to inverter manufacturers,
who often do not have
Verification, validation, and characterization is extremely valuable to inverter manufacturers,
who often do not have extensive in-house testing capabilities. Sandia should be provided with
the resources necessary to support development of inverters for the U.S. market.

Government can assist manufacturers in improving product reliability
by studying and documenting failure of inverters in the field.

Text Box: Suggested Role for Government Failure Documentation
Suggested Role for Government Failure Documentation
Text Box: A possible role for government would be to conduct an extensive study of PV installations to
document inverter failur
A possible role for government would be to conduct an extensive study of PV installations to
document inverter failures and provide the results to manufacturers.
Text Box: Documentation of Inverter Failures
Data of failure of inverters in the field is lacking. Most inverter manufacturers
Documentation of Inverter Failures
..Data of failure of inverters in the field is lacking. Most inverter manufacturers generally know the
number of shipped units that were returned by customers, and little more. They generally do not
look into what caused the inverter to fail.
..Larger companies are apparently capturing and documenting information on inverter field problems,
but information is considered confidential.
..A comprehensive database of inverter failures would enable manufacturers to understand areas of
weakness in designs and take corrective measures.

Documentation of information on key inverter components would
assist manufacturers with design choices.

Text Box: Suggested Role for Government Component Documentation
Suggested Role for Government Component Documentation
Text Box: A comprehensive study of inverter components would help manufacturers identify the best
available products.
However,
A comprehensive study of inverter components would help manufacturers identify the best
available products.
However, because components used in inverters are also used in many other applications, it is
likely this type of work should be conducted as crosscutting research to support DG inverters
and power electronics.
Text Box: Component documentation
Inverter manufacturers have commented there are substantial differences in the performance of
Component documentation
..Inverter manufacturers have commented there are substantial differences in the performance of
components (e.g. capacitors) available from different suppliers.
..Inconsistent specification, data sheets, and testing results exist on some of the key components for
inverters (e.g. capacitors, fans, electrical connectors, power semiconductors, etc…) making it difficult
for manufacturers to make proper comparisons of options.

Manufacturers need modeling tools to help with product development,
but do not have the resources to develop them.

Text Box: Suggested Role for Government Modeling Tools
Suggested Role for Government Modeling Tools
Text Box: While modeling tools would help manufacturers develop their products, developing such models
is challenging. Therefor
While modeling tools would help manufacturers develop their products, developing such
models is challenging. Therefore, resource requirements and the limitations in achievable
results with this type of work needs to be examined before making extensive investments in
new modeling tools.
Text Box: Modeling Tools
Manufacturers lack the resources to develop modeling tools for inverters. Such tools would enhance man
Modeling Tools
..Manufacturers lack the resources to develop modeling tools for inverters. Such tools would enhance
manufacturers’ ability to explore options and select the optimaldesign.
..Sandia has the expertise to develop inverter models, and this type of work has been done in the past.
However, one Sandia expert has commented that modeling of inverters was very difficult. But while
completely accurate models may be nearly impossible to achieve, simplified models could still be
useful.

Manufacturers would benefit from understanding the costs and
benefits associated with HALT and HASS testing.

Text Box: Suggested Role for Government HALT and HASS
Suggested Role for Government HALT and HASS
Text Box: Information and guidance regarding the value and applicability of HALT and HASS testing for
inverters would benefit t
Information and guidance regarding the value and applicability of HALT and HASS testing for
inverters would benefit the industry. The trade-offs on cost, reliability, and life improvement
need to be more fully understood.
A possible role for government would be to provide assistance tomanufacturers in setting up
HALT and HASS programs, as well as general guidelines to follow.
Text Box: HALT and HASS Testing Methods
Highly Accelerated Life Testing (HALT). This type of test subjects the inverter to extr
HALT and HASS Testing Methods
..Highly Accelerated Life Testing (HALT).This type of test subjects the inverter to extreme operating
conditions in order to identify weak points in reliability for new designs. Some of the larger
manufacturers conduct this testing, but most do not have resources or an understanding of proper
testing procedures to follow.
..Highly Accelerated Stress Screening (HASS). Production testing to screen products knowing the
operating and destruct limits based on HALT testing. Few manufacturers understand how to
perform this testing, and its value for PV inverters is not understood by most.

The success of HRII indicates that government should consider
funding another similar initiative.

Text Box: Suggested Role for Government Public-Private R&D Partnership
Suggested Role for Government Public-Private R&D Partnership
Text Box: A formal review of the HRII program should be completed and shared with the industry to allow
others to understand so
A formal review of the HRII program should be completed and shared with the industry to
allow others to understand some of the key findings.
At this point, the results of HRII appear promising. Pending an evaluation of final results and
appraisal of HRII success, another similar initiative may be a good use of DOE funds.
Use of similar approaches for DER inverter components should be explored.
Text Box: Public-Private R&D Partnership
The High Reliability Inverter Initiative (HRII), launched in 2002, will come to an end
Public-Private R&D Partnership
..The High Reliability Inverter Initiative (HRII), launched in 2002, will come to an end this year. The
contractors selected (GE, Satcon, Xantrex) are developing prototypes of advanced inverters. At least
one manufacturer has commented that their involvement in HRII has significantly impacted product
development, by allowing them to explore options that would otherwise have been left aside.
..It should be noted that Sandia received many responses to their RFQ, six of which were deemed
excellent. But only three manufacturers could be selected due tofunding limitations (~$5M).
..Programs such as this may be appropriate for development of advanced components such as
switches, capacitors, and connectors that would benefit the broader DER inverter industry.

Innovative inverter topologies could be a source for additional cost
reduction and reliability and performance improvement. A potential role
for government may be to fund studies to understand potential benefits.

Text Box: Suggested Role for Government Alternative Inverter Topologies
Suggested Role for Government Alternative Inverter Topologies
Text Box: Government could consider funding studies on the potential benefits of alternative inverter
topologies. Many benefits
Government could consider funding studies on the potential benefits of alternative inverter
topologies. Many benefits have been suggested, but there does not appear to be significant
direct evidence of the specific gains that might be achieved.
Research could focus on experimental topologies, with the objective of advancing the industry.
Text Box: Alternative Inverter Topologies
Innovative control and inverter design topologies have the potential to be a source o
Alternative Inverter Topologies
..Innovative control and inverter design topologies have the potential to be a source of cost reduction,
improved thermal management, and improved reliability. Several manufacturers have noted that
there could be many advantages to the exploration of alternativetopologies.
..Alternative topologies could be used to standardize “sub components” that could be used across
product lines or in power electronics for other DER products.

Government should consider conducting an assessment of performance,
cost, and reliability benefits that could be derived from wider adoption
of transformerlessinverters.

Text Box: Suggested Role for Government Ungrounded Arrays
Suggested Role for Government Ungrounded Arrays
Text Box: A sponsored study on the pros and cons of ungrounded arrays and elimination of transformers
could be a general benefi
A sponsored study on the pros and cons of ungrounded arrays and elimination of transformers
could be a general benefit to the DER industry. There is significant experience in Germany with
tranformerless inverters and transferring this knowledge to the United States would be
valuable to the industry.
Note:
Magnetek announced on January 9, 2006, that its transformerlessAurora inverters have been listed by
CEC. (source: Business Wire)
If the Aurora inverters are adopted by some PV system designers/installers, this could be an important
first step in allowing transformerlessinverters to enter the U.S. market.
Text Box: Benefits and Issues Associated with Ungrounded Arrays
The 2005 National Electric Code allows the use of ungrounded ar
Benefits and Issues Associated with Ungrounded Arrays
..The 2005 National Electric Code allows the use of ungrounded arrays, but local electric code and
utility interconnection in the United States still requires grounding. There are efficiency and cost
benefits associated with eliminating transformers, but there is not acceptance of other protection
schemes –and there are concerns about safety at local and utility levels. Local inspectors and
regulators do not generally accept other protection schemes.

Standards are a major complaint of manufacturers, but possible roles
for DOE in this area may be limited.

Text Box: Suggested Role for Government Standards
Suggested Role for Government Standards
Grid connection and installation:These standards are the domain of organizations like UL (UL 1741),
IEEE (IEEE 1547), and NFPA (NEC 2005). However, DOE may be able to influence these organizations
or provide leadership to help bring about the changes that inverter manufacturers are asking for. In
addition, the following specific recommendations have been made relative to UL 1741:
1.Subsidize the cost of acquiring the UL 1741 standard.
2.Subsidize the cost of attending UL 1741 meetings to encourage industry participation.
Communication:EPRI is leading the effort to develop a communication standard for DER. DOE
should support this initiative.
Performance metrics:Sandia and Endecon Engineering are currently developing the PV Inverter
Performance Test Protocol. Manufacturers have been asking for this type of standard, and support for
this activity should continue.
Text Box: Standards
Grid connection: Manufacturers repeatedly ask for standards to be harmonized, for ungrounded PV arrays
and
Standards
..Grid connection: Manufacturers repeatedly ask for standards to be harmonized, for ungrounded PV arrays
and transformerless inverters to be accepted, and for relaxationof installation requirements that retain
safety.
..Communication:Standards for communicating PV system information are needed for data monitoring and
for utility interaction. Without a single, universal standard, manufacturers will develop proprietary
standards that will lead to fragmentation and hamper growth of this technology.
..Performance metrics:Sandia and Endecon Engineering (now BEW) are currently developing the PV Inverter
Performance Test Procedure. Manufacturers have been asking for this type of standard, and support for this
activity should continue.

Understanding the role of incentive programs and policies for PVwill
be critical to the long-term growth necessary to meet cost,
performance, and reliability goals.

Text Box: Suggested Role for Government Policy Assessment
Suggested Role for Government Policy Assessment
Text Box: Government could fund a study of the impact of PV policy programs with the objective of
understanding the relationshi
Government could fund a study of the impact of PV policy programs with the objective of
understanding the relationship of program design to market growth, as well as options for
making U.S. policies more effective. Understanding the interaction of federal, state, and
municipal programs will be increasingly important to further industry growth.
Text Box: The Impact of Alternative Policies and Incentives for PV
Increasing market volume is one of the major drivers in achi
The Impact of Alternative Policies and Incentives for PV
..Increasing market volume is one of the major drivers in achieving cost and performance goals for
inverters. Market volume in the United States is growing, but not to the degree it has in Germany and
Japan.
..There is significant fragmentation in policies to promote the adoption of PV. California, New Jersey,
and New York lead the country with programs to buy-down the price of new systems. National
policy provides investment tax incentives. European feed-in tariffs have developed a much more
rapidly growing market and are driving most of the investment inthe industry.
..An assessment of impact of alternative policies would benefit the industry.

1.Photon International, Invasion of the inverters, April 2004.
2.Photon International, Market Survey of Inverters, April 2005.
3.Renewable Energy World, Choosing the right inverter, March-April 2004.
4.Photovoltaics, Looking to Spain, September-October 2004.
5.R.West et al., Status and Needs of Power Electronics for Photovoltaic Inverters: Summary Document,
Sandia Report
SAND2002-1085, May 2002.
6.Dan Ton, Ward Bower, Summary Report on the DOE High-tech Inverter Workshop, January 2005.
7.Dan Ton, Ward Bower, Summary Report on the DOE Workshop On a Systems-driven Approach to Inverter
Research and
Development, September 2003.
8.Gonzalez et al., PV Inverter Testing, Modeling, and New Initiatives, NCPV and Solar Program Review
Meeting 2003,
NREL/CD-520-33586.
9.Bonn, Russell H., Developing a “Next Generation” PV Inverter, IEEE 2002.
10.Sarjeant et al., Capacitive Components for Power Electronics, IEEE 2001.
11.IEA, Grid-connected photovoltaic power systems: Survey of inverter and related protection equipments,
PVPS Task V
Report IEA-PVPS T5-05: 2002, December 2002.
12.Jan Schaeffer et al, Learning from the Sun, Final report of the Photex project, August 2004.
13.Jan Schaeffer et al, Photovoltaic Experiences, Synthesis report of the Photex-project, June 2004.
14.Solar Electric Power Association, Residential PV Systems Cost Report, December 2001.
15.Solar Electric Power Association, Large Systems Cost Report –2001 Update, September 2001.
16.Photon International, PV industry in high spirits at Intersolar, August 2005


Text Box: References
References

1.Mitsubishi
2.SMA
3.Fronius
4.Outback
5.GE
6.Xantrex
7.Sustainable Energy Technologies
8.Heliotronics
9.SunPower
10.Siemens
11.PowerLight
12.SolarMax


Text Box: References
References
Text Box: Conference Interviews June 6-9, Barcelona, Spain
Conference Interviews June 6-9, Barcelona, Spain

Shannon Graham| Managing Consultant

sgraham@navigantconsulting.com

415-399-2164 direct

Etienne Parent| Consultant

eparent@navigantconsulting.com

781-270-8428 direct

David Walls| Director

dwalls@navigantconsulting.com

781-270-8436 direct

Paula Mints| Associate Director

pmints@navigantconsulting.com

415-356-7174 direct

Lisa Frantzis| Director

Lfrantzis@navigantconsulting.com

781-270-8314 direct

Text Box: NCI Contacts
NCI Contacts
www.millenniumplanet.com