News Article

New, Cost-Competitive Solar Plants for Electric Utilities Challenge
Source: DOE Success Story ( click here to go to the source)

Featured firm in this article: Arzon Solar LLC of Seal Beach, CA

The price of photovoltaic solar panels fell rapidly from about $30 per Watt in 1975 to about $5 per Watt a decade later. However, the production cost of a standard solar panel for the most part leveled off for a number of years at just under $5 per Watt, remaining too costly for most large, utility-scale installations. With the advent of new solar concentrator systems, it became possible to replace expensive solar cells with inexpensive plastic lenses that focus sunlight onto small cells. This technological advance enabled lower panel manufacturing costs, improved cell performance, and increased utility-scale solar system efficiencies.

In the 1980s, the U.S. Department of Energy supported innovative research at the National Renewable Energy Laboratory that led to the development of multijunction solar cells with the world's highest conversion efficiencies--up to 50% higher than the highest silicon solar cell efficiencies. By the late 1980s, the Electric Power Research Institute (EPRI) had developed a high-concentration photovoltaic (HCPV) system which they believed to be a promising option for utility-scale solar power plants. However, one technical challenge they faced was the rapid degradation of solar cells under the intense ultraviolet radiation in concentrated sunlight.

Innovating Solutions
In 1989, staff at the newly-formed Amonix tackled the solar cell degradation problem. Within a year, they had stabilized the cell and started working with EPRI to develop the remaining system, including the lens, structure, and tracking system. With DOE EERE SBIR funding, Amonix redesigned the photovoltaic cell unit and integrated the cell, circuit board, and heat sink into a single cell receiver plate for economical, large-scale production. The company also redesigned the rest of the system for improved manufacturability using funding from EPRI, DOE, and private sources. The result: the Amonix MegaModule.

Although Amonix holds the world record for silicon solar cell efficiency at 27.6%, the world record for multijunction cells is now 50% higher. Amonix has been able to increase MegaModule performance by 50% by replacing its production silicon cells with production multijunction cells having efficiencies over 37%. Today's commercial and defense satellites use multijunction solar cells with conversion efficiencies above 35% (the record is over 41%). Performance in space is critical and multijunction solar cells have demonstrated unbeatable performance. By bringing these multijunction solar cells "down to earth" and incorporating them into the MegaModule design, Amonix has significantly improved MegaModule efficiency-- further reducing the cost of utility-scale solar electricity.

The MegaModule sections are manufactured in a plant and easily trucked to the installation site (the photo depicts the 7700 system with 7 MegaModules on each pedestal). In 2001, Amonix was awarded a patent for their method of making the cell receiver plate. Since then, Amonix has worked with electric utilities throughout the southwestern U.S. to develop and test six generations of this system, which has allowed the company to resolve remaining technical problems and produce an efficient, reliable system.

Amonix began producing the improved MegaModule in 1998 and has already installed 28 systems in the U.S., with a combined peak power capacity of 700 kW. Since 2006, Guascor Fotón has installed over 400 hundred of these systems in Spain, where market incentives provided the opportunity for cost-effective utility power plant projects. Amonix found Guascor Fotón's experience to be invaluable for identifying how best to deploy MegaModule systems on a large scale and help make the most of future market opportunities.