General Framework

Beginning in October, the U.S. DOE reorganized its renewable energy work into a new National Solar Program. The U.S. DOE was the leading funding source for PV research and development in 2001 and it offered the resources of the national laboratories to assist in the PV industry’s applied research and development (R&D) activities. The Office of Energy Efficiency and Renewable Energy, led the national laboratories to develop comprehensive operating plans based on strategic, multiyear plans that respond to the broad policies for energy R&D determined by the executive and legislative branches of the federal government. The National Center for Photovoltaics (NCPV) worked with the PV industry through various cost-shared programs to develop and improve component designs, device manufacturability and systems. Education, technical transfer, technical assistance and competitive contracts were used extensively to accomplish the work in 2001. PV-related activities funded by the DOE were balanced between PV cell and module development, manufacturing, balance-of-system and system technologies. The U.S. Department of Energy web site (http://www.eren.doe.gov/pv/) provides up to date information on and links to all aspects of the PV activities in the U.S.

The “Industry Roadmap,” refined in December 2000 unifies the vision and long-term (2000-2020) strategies and goals for the PV industry. The vision provides the electrical/energy consumer competitive and environmentally friendly energy products and services from a thriving U.S.-based solar electric power industry. The “DOE PV Program 5-Year Plan (2000-2004)” that was written in concert with the industry roadmap plan helps to guide the national PV activities. In addition, the U.S. DOE Million Solar Roofs Initiative promoted the reduction in greenhouse gas and other emissions and State and local partnerships, financial tools, consumer awareness, and support with codes, standards, and certification programs.

The National Center for Photovoltaics (NCPV), an alliance of organizations, serves as the focal point for the nation’s capabilities in PV technologies and has proven to be an effective structure for planning and implementing the national PV activities. The R&D goals and strategies are formulated each year by a governing board in concert with the “Industry Roadmap” and through an all-encompassing annual operating plan.

PV technologies for both thin-film devices and crystalline devices continued partnership programs in 2001. The Thin-Film Partnership Program and the Crystalline Silicon Research Cooperative collaborated with manufacturers on technology issues that were common to all manufacturing processes and non-proprietary in nature to pool the nation’s resources in order to maximize technology advancement.
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National Programme

The total FY2001 federal budget for the Photovoltiac component of the National Solar Program totaled USD 74,26 million. Additional support for PV-related projects came from state and local governments, the PV industry, and utilities.

The NCPV relies on the core expertise of NREL and Sandia to create, develop, and deploy PV and related technologies. Other national PV resources that the NCPV draws on are Brookhaven National Laboratory, two Regional Experiment Stations (the Florida Solar Energy Center and the Southwest Technology Development Institute), and U.S. DOE Centers of Excellence in PV at the Georgia Institute of Technology and the University of Delaware (Institute of Energy Conversion). In addition, more than 100 university, industry and utility research partnerships across the country are linked together to function in a unified way. The NCPV awards most of its federal funds through competitive procurements to industry, universities, and other research centres.
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Research and Development

Thin-film devices and materials development continued through the NCPV and the Thin-film Partnership Program. Thin-film devices include amorphous silicon (a-Si), copper indium diselenide (CIS), copper indium gallium diselenide (CIGS), cadmium telluride (CdTe), thinfilm silicon and others. The Thin-film Partnership Program helped to commercialize these promising technologies and began awarding contracts for the next round of research to 19 universities and 14 companies. A total of USD 40 million will be awarded while awardees will cost share USD 13 million. Among this year's achievements were efficiency records, gains in cell and module processing techniques, and new commercial production facilities. Responding to sustained research efforts, the efficiency of thin-film devices is steadily rising. In 2001, large area amorphous silicon (a-Si) modules showed stable efficiencies that were up to 7,9%; cadmium telluride (CdTe) modules that were rated 11,0% efficient; and CIS-based modules that were rated up to 12,1% efficient.

• Research on Amorphous Silicon (a-Si)
  Research has moved efficiencies of a-Si devices toward the national goal of 13% efficiency and methods for increasing the deposition rate of a-Si were successful. United Solar Systems increased a-Si production to 3.8 MW in 2001. BP Solar continues to operate its 10-MW/year plant with enhanced throughput that produces tandemjunction, a-Si alloy modules in the 43 to 50-W range with glass-to-glass encapsulation.

• Research on Cadmium Telluride (CdTe)
  PV devices using CdTe can be manufactured using potentially low-cost techniques such as spraying, electrodeposition, and high-rate evaporation. Achieving high laboratory efficiencies using these low-cost techniques is an important objective of the National Solar Program. To date, more than ten techniques have been used to grow CdTe layers resulting in cells operating at efficiencies greater than 15%. Three of these methods are currently used in industry. BP Solar produced a CdTe module with an aperture area efficiency of 11% and power output of 92,5 W. First Solar, LLC has advanced its ultrahighrate vapour transport deposition through collaboration with the NCPV.

• Research on Copper Indium Diselenide (CIS) and Copper-Indium-Gallium-Selenide (CIGS)
  Two major goals for CIS research are to transfer years of government- sponsored research to industry for pilot-scale manufacturing and to produce commercial modules. NREL scientists achieved replicable CIGS cells with efficiencies of 21,1% under 14-sun concentration. Industry explored new deposition systems for large-area CIS devices. The Institute of Energy Conversion produced solar cells with 16,9% efficiency using a new Cu(InAl)Se2 absorber layer.
  Commercial products using CIS alloys were sold by Siemens Solar Industries (SSI) and by Global Solar in 2001. SSI produced 5- to 40-W PV modules made of CIS alloys that were up to 10% efficient. Global Solar produced new flexible modules (4,9% efficient) for a variety of field applications. SSI developed the new products using copper-indium-gallium-sulfur-selenide (CIGSS) under contract to the Thin-film PV Partnership Program.

• Research on Crystalline Silicon (c-Si) PV
  Because more than 90% of PV power systems sold today are made of crystalline silicon (c-Si), improvements to this technology have the potential for quick advancement to the marketplace. Fundamental research for scientific advances through the Crystalline Silicon Research Cooperative and other programs in crystalline silicon technologies continued in 2001. The program sponsored the 11th Workshop on Crystalline Silicon Materials and Processes to effectively communicate research results. Researchers at Sandia developed a plasma texturization process for multi-crystalline cells known as reactive ion etching. The process boosts the performance of cells by 10%.

• Research and Development of the Balance-of-System
  Research within the industry and the national laboratories has explored improved solid-state switching methodologies for inverters, new control firmware and software, new balance-of-system hardware designs, and entire PV systems that are cost effective. Inverter improvements include higher efficiency, reduced operating losses, lowered cost, improved quality control, smaller size and conformance with anti-islanding and code requirements. Many of the new grid-connected installations also use battery storage. Sandia maintains a program to evaluate and improve batteries and charge controllers for PV applications. Issues pertaining to environment, safety and health remained an essential aspect of working with the balance-of-system industry and were included in all work sponsored by the National Solar Program.

• Research on High Performance and Concentrating PV
  The National Solar Program contains a 10-year program goal to double the efficiency of multi-junction thin-film modules. There is also a goal to demonstrate a high-efficiency III-V cell in a pre-commercial concentrator module. To help achieve this objective, the High Performance PV Initiative was begun in 2001. The NCPV and Spectrolab are collaborating toward a goal of a 40% cell under concentrated sunlight. Spectrolab demonstrated a 34%-efficient cell under 600-sun concentration. Work continues on several fronts to develop materials that will perform well at very high concentrations of sunlight.

• Systems Research and Development
  A systems engineering program that included a balance-of-system program was accelerated this year with Sandia leading efforts to fund evolutionary changes to power processing hardware resulting in improved reliability and performance. The reliability of required switchgear, ground-fault detection and interruption equipment, and component safety certification programs was also funded. Sandia continued working with industry in 2001 to improve "Total Quality Management" programs in the manufacturing and assembly areas. Sandia also assisted industry in “Highly Accelerated Life Tests (HALT™)” and “Highly Accelerated Stress Screens (HASS™)” to improve quality and reliability of hardware. The test facilities at Sandia and NREL continue to contribute significantly to all of the reliability-improving programs.
  NREL and Sandia conduct module performance and durability studies for manufacturers based on data from several test sites. For new modules or for ones that have operated in the field for years, researchers collect data on electrical performance, extent of delamination, integrity of solder joints, and properties of encapsulants. Tests include outdoor electrical performance, dark current/voltage (I-V), infrared (IR) imaging, ultraviolet (UV) inspection, solder-joint metallurgy, and ultrasonic characterization, as well as destructive testing for specific failure modes.
  An inverter test facility at Sandia provides for hardware characterization, surge testing and accelerated life testing. A new 30-kW hybrid test bed for inverters is designed for grid-connected or standalone PV systems. In FY 2001, Sandia designed and began operation of a Distributed Energy Test Laboratory (DETL) that includes a 75-kVA microturbine; a 90-kVA diesel; and load banks that are resistive, inductive, and capacitive in nature. The product of an agreement with the Salt River Project and Sandia, this DETL can be used to study the effects of any distributed generation system (including PV and PV hybrid systems) on electrical utility operation.
  NREL maintains the Outdoor Test Facility (OTF) to test performance and reliability of solar cells, modules, and small (1–5 kW) systems. The OTF also calibrates primary reference cells for use in house, by other national laboratories, by industry, and by universities.
  Researchers at the OTF measure performance in actual outdoor tests and using solar simulators indoors. Indoors at the OTF, modules are tested for failure and performance in conditions of high voltage, high heat, high humidity, flexing, static loading, and simulated hail strikes. Outdoors, test beds at the OTF measure long-term performance and stability. Two test beds perform stress tests of modules under accelerated conditions of high voltage and high sunlight concentration.
  Sandia sponsored a Photovoltaic System Symposium in Albuquerque, which was attended by more than 200 people from industry, government, utilities, and educational institutions. Participants shared diverse experiences in implementing PV projects and discussed a systems approach to meeting the 20-year production goals of the PV industry roadmap. Such an approach includes increasing reliability, improving performance, reducing life-cycle costs, removing barriers, and expanding markets.

  Although manufacturers are now offering 10- to 15-year warranties on PV modules, PV systems that operate reliably for 25 years are the goal of the PV system activities. To reach that goal, the program is supporting research and analysis using field data and models to identify areas for further technical development. Sandia drafted a “PV System Reliability Plan” in consultation with industry. The plan recommends continuation of several activities such as: developing a reliability database to improve understanding of the performance of real systems; examining PV systems and components after extended operation in the field to identify sources of performance degradation or failures that could be prevented by changes in manufacturing; modelling system performance to identify fault-tolerant designs, sensitivity to component failure, and cost-effective component replacement strategies; and working with industry and users to resolve technical or institutional barriers to system reliability.

Manufacturing and implementation

• Industry Roadmap
  Success of the PV component of the National Solar Program depends on the direction, resources, best scientific and technological approaches, use of the best technologies and continued efforts of the best and brightest among industry, federal laboratory and university partners. The NCPV worked in concert with the industry to revise the “Industry Roadmap” to support work that focused on the roadmap’s vision and strategies to provide competitive PV products and services.

• Photovoltaic Manufacturing
  In 2001, the U.S. PV industry marketed about USD 1 billion of the world’s USD 2,5 to 3,0 billion of product. To maintain technology leadership and market share, improvements in product must move from U.S. laboratories to the world marketplace. Against this backdrop of a growing market, the PV Manufacturing R&D Project initiated a new solicitation, “Photovoltaic Manufacturing R&D—Inline Diagnostics and Intelligent Processing in Manufacturing Scale-Up.” This solicitation encourages teams to share the cost of high-risk research to develop intelligent processing for larger scale manufacturing that will be the foundation for achieving the goals set out in the U.S. Photovoltaic Industry Roadmap. Since Congressional funding for manufacturing research and development began in 1991, great progress has been made in reducing the cost of PV systems and improving the performance and reliability of commercial products.
  Work under previous subcontracts awarded under PV Manufacturing Technology (PVMaT) solicitations was completed in 2001, just as the new set of contracts was awarded. Final reporting will continue into FY 2002. The 14 subcontracts awarded in FY 1998 will total about USD 60 million over a 3-year period with 48% subcontractor cost-sharing.

• Electrical and personnel safety through codes and standards
  As more installations of PV systems occur, the electrical and personnel safety of the systems are undergoing more thorough examinations by designers, installers, inspectors and users. Vital utility and industry issues, such as codes and standards, are continuing activities in the National Solar Program. The program supported work to provide a consensus of industry input into the National Electrical Code® (NEC®), listing and certification standards, and numerous standards activities in both the domestic and the international arena. An "Industry Forum" proposed 34 changes in Article 690 of the NEC for the upcoming 2002 Code and most of those proposed changes are now included in the 2002 Code, published in 2001.
  The IEEE929-2000 standard spearheaded by Sandia was published in 2000 and now serves to help remove barriers to interconnection of PV systems to the utility grid. The NCPV headed up the IEEE PV standards activities and also actively participated in the International Electrotechnical Commission activities for PV-related international standards. Underwriters Laboratories amended the UL1741 "Standard for Static Inverters and Charge Controllers for Use in Photovoltaic Power Systems" and is now considering expansion of the standard to include inverters for all distributed generation.
  PowerMark Corporation continued as a non-profit certification body. PowerMark previously recognized the Arizona State University PV Testing Laboratory (PTL) and approved them for performing module certification tests based on the accreditation certificate they received from the American Association of Laboratory Accreditation. Module models have been qualified to IEEE1262/IEC61215 or IEEE1262/IEC61646 standards since the work began in 1996. The PTL continues to test module types to the UL1703 PV module standard to determine their suitability for listing and has a reciprocity arrangement with European testing organizations.

Market Development

The National Solar Program provided continuing support for state supported PV applications using assistance through the Interstate Renewable Energy Council (IREC). Much of this work provided PV applications and education for parks and public spaces through the “Photovoltaics for Utilities (PV4U)” program. This approach to removing barriers to PV for utilities is a network of State working groups that promote PV. Working with the States for “A National Certification Program for Practitioners” and later PV hardware became a focal point for the IREC program in 2001 featuring workshops and special sessions at conferences.

Making way for new strategies, the phased research and product development program known as PV: BONUS was nearing completion in 2001. Initiated in 1993, this was the first DOE effort to foster the development of products for the building industry that included photoelectric conversion features. The project conducted competitive solicitations that resulted in 38 partnerships and 10 new products for the residential and commercial buildings market. Partnerships that brought products to market included members with knowledge of the building industry, as well as photovoltaics, who worked together to design, develop, and manufacture the products.

There is a huge potential market for installing solar electric systems as an alternative to upgrading aging power lines to existing electric water pumps in the U.S. If 5% of all applications in the rural electric cooperative system were replaced with PV, the market would equal 50 MW. Barriers to this large potential market for PV systems are being addressed when NCPV personnel provide analysis and technical assistance to organizations such as the U.S. Department of Agriculture’s (USDA) Rural Utility Service, the U.S. Department of Defense, the U.S. Agency for International Development, the Florida Solar Buildings Program, the U.S. Bureau of Reclamation, Mexico’s Agricultural Secretariat, the Salt River Project, and the Navajo Tribal Utility Authority (NTUA).

No major national demonstration programs were active during 2001. Several new programs were sponsored by various sectors of state governments and utilities, most notably California. Deregulation of the electric utilities and localized energy shortages have spurred several state programs that require installation of PV energy systems along with new R&D efforts aimed at fielded PV systems.

International work included the Mexico Renewable Energy Program that was sponsored by the U.S. Agency for International Development (USAID) and supported by the U.S. Department of Energy to institutionalize the use of renewable energy technologies. This program had been honored as one of the most successful renewable energy programs for USAID and now serves as a model for increasing the use of renewables in other parts of the world. These projects were implemented in partnership with local Mexican organizations in each geographical or political area to purchase, finance, install and maintain the sustainable systems. This program is resulting in widescale system replication, through increased awareness of the benefits of renewable energy technologies, and improved private sector capacities to serve the market. In 2001, Sandia distributed a new CD guide in Spanish for PV water pumping systems.

The NCPV support, such as training and technical assistance in Bolivia, Brazil, China, Ghana, Guatemala, Honduras, India, Indonesia, Kenya, Mexico, Morocco, Nigeria, Pakistan, the Philippines, Russia, South Africa, and Venezuela has helped U.S. companies make inroads into a fast-growing international market.
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Future Outlook

The U.S. DOE Million Solar Roofs Initiative promotes the use of solar thermal and PV to reduce the energy demands of buildings. It enables businesses and communities to install solar systems on one million rooftops across the U.S. The U.S. DOE leads this initiative by working with partners in the building industry, local governments, state agencies, the solar industry, electric service providers, and non-governmental organizations to remove market barriers and strengthen grassroots demand for solar technologies. The “MSRI Action Plan” serves as a guide for the initiative and includes: assistance to MSR “State and Local Partnerships”` through regional DOE offices, enhancement of financial tools available for solar energy, increased consumer awareness, strengthened ties to other Federal Agencies, encouraged adoption of uniform interconnection standards and codes, support for R&D and testing programs, establishment of certification programs, and encouragement to builders and developers to include solar energy systems.
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Further reading about the USA

• USA - Country information