Description

Topics covered include:

• Application Segments
• Alternative Energy Technologies
• Recent Developments in the Photovoltaics Industry
• Architectural and Technology Trends and Developments
• Business Trends and Developments
• Cost Dynamics of Photovoltaic Power
• Cost Dynamics of Disruptive PV Inverter Technology
• Policy and Regulatory Framework for Development
• Competitive Environment

The emergence of disruptive power architectures including microinverters and dc-dc converters will be one of the most important trends in the photovoltaic (PV) market in the near-term. The shortcomings inherent in today’s central inverter architecture are expected to provide a host of opportunities for several new technologies. In fact, there are a growing number of companies developing products and technology specifically designed to generate more power from the PV panels already on the market. A distributed inverter architecture using either of two specific disruptive technologies, microinverters or dc-dc solutions, are expected to present a significant challenge to the conventional central inverter architecture over the coming years.

Among the areas covered in our latest analysis are the technology, architecture and packaging trends affecting the industry, as well as a thorough discussion of new and emerging technologies and materials, applications, potential threats and the latest regulatory developments and standards.

Over 25 illustrations are presented depicting a variety of inverter system architectures, schematics and comparisons, technologies, product introductions, packaging solutions, efficiency standards and other relevant information. The focus of this comprehensive analysis provides decision makers with a detailed and insightful look into the current and future opportunities and threats available in the disruptive technology area of microinverters and dc-dc solutions.

Executive Summary

The emergence of disruptive power architectures including microinverters and dc-dc converters will be one of the most important trends in the photovoltaic (PV) market in the near-term. The accelerating worldwide growth in grid-tied PV will be driven by a number of factors including: improved technology, cost reductions, strong deployment incentives, growing consumer interests, renewable portfolio standards, climate change concerns, and a host of other policy mandates.

The number of relatively large PV projects feeding power directly to the grid will increase, but most systems will be deployed in behind-the-meter applications, where the technology competes with the retail rate of delivered electricity rather than the wholesale cost of energy supplied by central-station generating plants. In fact, worldwide PV sales have surpassed $10 billion annually and total installed PV capacity is projected to exceed 25 GW by 2011.

As a result of the growing demand for PV, the outlook for inverters used in PV systems is expected to remain strong. There are a large number of PV system configurations available and a wide range of inverters on the market. Some models use transformers and some are transformerless, and many come with sophisticated communications and monitoring systems.

Regardless of the type of inverter used, the system is usually configured in traditional central inverter architecture. Since the PV industry is constantly evolving, inverter manufacturers must continually design new products.

Despite the ubiquitous nature of the central inverter system, it has a number of limitations. It relies on one device (the inverter) that when faulty, brings down the entire system, and its inherent design means the weakest panel in each string eliminates the benefits of the better performing PV panels. (The “weakest link” module determines the string current and has a disproportionate impact on overall PV system performance.)

This latter point is especially important because PV systems are constantly exposed to the elements and that means one or more panels over the lifetime of the system will be covered by debris, dust or another form of shading. In fact, some panels may fail or weaken as a result of age or simply lose power due to panel mismatch.

The shortcomings inherent in the central inverter architecture are expected to provide a host of opportunities for several new technologies. In fact, there are a growing number of companies developing products and technology specifically designed to generate more power from the PV panels already on the market. A distributed inverter architecture using either of two specific disruptive technologies, microinverters or dc-dc solutions, are expected to present a significant challenge to the conventional central inverter architecture over the coming years.

A significant advantage both of these disruptive technologies have over traditional central inverter technology is the ability to perform maximum power point tracking (MPPT) at the panel level. The goal of the MPPT algorithm is to extract the greatest power available from the solar array. (The better the MPPT algorithm, the greater the power output.) Due to variation in shading, dirt, and aging of solar panels, individual panel voltages will vary, causing the output voltages of strings of panels to vary.

In addition to improvements in efficiency, the ability to reconfigure PV arrays without additional complex string calculations and improved operational flexibility, another opportunity for both microinverter and dc-dc solutions is the further development and availability of communications systems for both commercial and residential PV systems. Manufacturers of disruptive technologies such as microinverters and dc-dc solutions have picked up on this trend and are incorporating them into their respective systems.

Challenges and opportunities relating to distributed PV integration will be strongly influenced by the current and future attributes of PV and balance-of-system technologies. Among the more promising is the development of the building-integrated PV (BIPV) systems.

A building-integrated PV system involves integrating photovoltaic modules into the building envelope material and power generators. Evidence of this opportunity can be seen in the number of successful BIPV projects worldwide, ranging from individual residential units to large commercial developments.

The demand for technology to address the problem of PV shading is another area of opportunity for both microinverters and dc-dc solutions. Due to the nature of solar array configuration, small amounts of shade (for example, shading of less than 10 % of the surface area of a PV system) can lead to disproportionate power losses of more than 50%.

One completely shaded cell can reduce a solar panel’s output by as much as 75%, and three shaded cells can decrease 93% of the panel’s output. Common causes of shade include structural objects such as trees, chimneys and dormers, and intermittent debris including falling leaves, bird droppings, dust and clouds passing overhead, which is an unavoidable challenge that cannot be engineered out of an installation.

In an effort to promote the use of disruptive technologies such s microinverters and dc-dc solutions, a number of microinverter and dc-dc solutions manufacturers have adopted a strategy of partnerships and alliances within the industry. In fact, a number of solar suppliers and utilities have made either alliances or acquisitions of distributed electronics vendors in what is clearly a validation of the potential for both of these new disruptive technologies.

The Darnell Group expects that the trend towards business partnerships and alliances between manufacturers of disruptive technology and established PV distributors, manufacturers and distributors will continue to grow as the technology becomes more established.

An inverter is the most critical electronic component in any PV photovoltaic system. Among the challenges facing inverter manufacturers are maintenance issues, since in a PV system, the inverter is the component with moving parts.

In order to compete with the traditional inverter architecture, end users of both microinverters and dc-dc solutions must be assured that the products they use will come with warranties comparable to traditional solutions. Manufacturers of products considered to be disruptive technology, such as microinverters and dc-dc solutions, realize this and offer a range of warranty options.

The market forces affecting the traditional PV inverter industry also apply to the disruptive technologies presented in this report. Especially important are interconnection and regulatory standards.

Despite the efforts of a number of government and regulatory bodies worldwide, the goal of achieving agreement in both is still a work in progress. However, there are a number of groups working on electrical interconnection standards with the objective of reducing or removing barriers between distributed generation technology and the utility grid.

A survey done found that most projects, including PV, meet some sort of resistance from the utility companies when they try to interconnect with the grid. The expensive and sometimes difficult interconnection requirements currently in place worldwide comprise a key barrier to the increased use of alternative systems.

One of the more interesting technologies being developed to drive interconnection is the development of a “smart grid.” However, removing current interconnection requirements is not as simple as changing policies, and a method of resolving these barriers is ongoing.

Among the areas covered in our latest analysis are the technology, architecture and packaging trends affecting the industry, as well as a thorough discussion of new and emerging technologies and materials, applications, potential threats and the latest regulatory developments and standards.

Over 25 illustrations are presented depicting a variety of inverter system architectures, schematics and comparisons, technologies, product introductions, packaging solutions, efficiency standards and other relevant information. The focus of this comprehensive analysis provides decision makers with a detailed and insightful look into the current and future opportunities and threats available in the disruptive technology area of microinverters and dc-dc solutions.

Companies Mentioned

3Degrees, Accurate Solar Power, Act Solar, Advanced Energy Industries, AEE, Akeena Solar, altPower, Applied Materials, Applied Ventures, Ascension Technology, Atlantis Energy Systems, Azuray Technologies, BankInvest New Energy Solutions, Blue Ice, Borrego Solar, BP Solar, California Energy Commission, California Public Utilities Commission, CFM Equipment Distributors, Chevron Energy, Coalition for Green Bank (CGB) consortium, Concordia University, DC Power, Deutsche Bank, Direct Grid Technologies, Dispower, Dow Corning Corp., eIQ Energy, Electric Power Research Institute, Enecsys Micro Inverters, Energy Recommerce, Enphase Energy, Epcos, Exceltech, FedEx Kinkos, First Solar, Flextronics, Fronius, Focused Energy, Fotowatio Renewable Ventures, General Electric, GE Energy Financial Services, Georgia Institute of Technology, German Standardization Committee for Photovoltaics (DKE), Green Ray Solar, HaWi Energietechnik AG, Gehrlicher Solar AG, Hemlock Semiconductor, Integeam, IEEE, International Electrotechnical Commission, Interstate Renewable Energy Council, Island Technologies, Isofotón , Kaco New Energy GmbH, Laurence Berkeley National Laboratory, Madrone Capital Partners, Magnetek, MET Laboratories, Ministry of Economy, Trade and Industry, Mitsubishi Electric, Moser Baer India, Ltd., National Electrical Manufacturers Association, National Fire Protection Association, National Semiconductor, National Renewable Energy Laboratory, New Energy and Industrial Technology Development Organization, New Jersey PSE&G, New York State Energy Research and Development Authority, New Zealand Ministry of Economic Development, Nippon Oil Corp, OKE Services, Optisolar, Outback Power, Pacific Gas & Electric Corp., Panasonic Components, Petra Solar, Power-One, PV Powered, REC Solar, RockPort Capital Partners, San Diego Gas & Electric, Sanyo Electric, Satcon Technology, Schott Solar, Sentinel Power Systems, Sharp Corp. SMA Technologies AG, SmartSpark Energy Systems, Solar AG, Solar Bridge Technologies, Solar Edge, Solar Depot, Solar Design Associates, Solarex, Solectrica Renewables, Soliant Energy, Southern California Edison, Studer Innotec, Sun Edison, Sustainable Energy, Suntech Power Holdings Co., Ltd., SunWize,Third Point Ventures, Tigo Energy, Toshiba Corp., Underwriters Laboratories, University of Phoenix, US Air Force, US Department of Energy, US Environmental Protection Agency, Wal-Mart, Wellington Partners, Xantrex

Introduction 4
Application Segments 6
Alternative Energy Technologies 6
The Current Photovoltaic Market 6
Recent Developments in the Photovoltaic Industry 8
Increase in the Production of PV Modules and Capacity 8
Changing Cost Dynamics in the PV Module Industry 10
Architectural & Technology Trends and Developments 11
Current PV Inverter Architecture and Technology 11
Opportunities for New Technologies 13
Microinverter Architectures 14
Architectures Using DC-DC Solutions 20
Communications/Monitoring Systems 26
Building Integrated PV 28
PV Shading 32
Microgrids 36
Developments in Packaging, Technology and Materials 36
Business Trends and Developments 40
Partnerships and Business Alliances 40
Warranties 42
Cost Dynamics of Photovoltaic Power 43
Cost Dynamics of Disruptive PV Inverter Technology 45
Policy and Regulatory Framework for Development 46
Adoption of Feed-in Tariffs 46
Renewable Portfolio Standards 47
Interconnection with the Utility Grid 49
Net Metering 52
Standards and Regulations 54
Renewable Energy Certificates 55
Direct Subsidies and Tax Incentives 57
Legislative Policies 58
Competitive Environment 59
Direct Grid Technologies 60
eIQ Energy 61
Enecsys Microinverters 62
Enphase Energy 63
Green Ray Solar 64
National Semiconductor 66
Petra Solar 67
SMA OKE 68
Solar Bridge 69
Solar Edge 70
Tigo Energy 72

List of Figures

Figure 1 –Typical Central Inverter 12
Figure 2 – Conventional PV Architecture 13
Figure 3 – Distributed PV Architecture Using Microinverters 15
Figure 4 – Illustration of an Enphase Energy Microinverter 16
Figure 5 – Distributed PV Architecture Using Embedded Microinverters 17
Figure 6 – Rooftop Entry Canopy Microinverter PV System 18
Figure 7 – Petra Solar Microinverter PV System 19
Figure 8 – Distributed PV Architecture Using DC-DC Solutions 21
Figure 9 – National Semiconductor Solar Magic Power Optimizer 22
Figure 10 – Tigo Energy Module Maximizer 23
Figure 11 – Tigo Energy Module Maximizer Attached to PV Panel 24
Figure 12 – Illustration of a SolarEdge DC-DC Solution 25
Figure 13 – Enphase Microinverter Communications System 27
Figure 14 – Building Integrated Photovoltaic System 29
Figure 15 – Building Integrated Photovoltaic System Structural Example 30
Figure 16 – Problem with PV Shading in Current PV Systems 32
Figure 17 – Proposed Solution to Problem with PV Shading 33
Figure 18 – PV Array Wired in Series 34
Figure 19 – PV Array Wired in Parallel 35
Figure 20 – Example of a Microgrid Configuration 37
Figure 21 – Conventional Inverter Using Electrolytic Capacitors 38
Figure 22 – Enecsys Inverter Using Thin Film Capacitors 39
Figure 23 – Cost Comparison of Photovoltaic Energy 44
Figure 24 – IEEE 1547 Series Interconnection Standards 50
Figure 25 – Nature of Main Interconnection Guidelines in Europe 51
Figure 26 – Net Metering for PV in the US 53
Figure 27 – Renewable Energy Certificates 56