The 25 percent-efficient GaAs Cassegrainian concentrator cell

Very high-efficiency GaAs Cassegrainian solar cells have been fabricated in both the n-p and p-n configurations. The n-p configuration exhibits the highest efficiency at concentration, the best cells having an efficiency eta of 24.5 percent (100X, AM0, temperature T = 28 C). Although the cells are designed for operation at this concentration, peak efficiency is observed near 300 suns (eta = 25.1 percent). To our knowledge, this is the highest reported solar cell efficiency for space applications. The improvement in efficiency over that reported at the previous SPRAT conference is attributed primarily to lower series resistance and improved grid-line plating procedures. Using previously measured temperature coefficients, researchers estimate that the n-p GaAs cells should deliver approximately 22.5 percent efficiency at the operating conditions of 100 suns and T = 80 C. This performance exceeds the NASA program goal of 22 percent for the Cassegrainian cell. One hundred Cassegrainian cells have been sent to NASA as deliverables, sixty-eight in the n-p configuration and thirty-two in the p-n configuration

PVMaT improvements in the manufacturing of the PVI Powergrid{trademark}: Final technical report, 27 October 1997--31 October 1998

Photovoltaics International, LLC (PVI), is improving the manufacturing of the Powergrid{trademark} under the Photovoltaic Manufacturing Technology (PVMaT) program in five basic areas: development of an advanced, state-of-the-art lens extrusion system; development of an advanced, state-of-the-art module side extrusion system; development of a second generation automated receiver assembly station; development of low-cost roll-formed steel panel frame members; and development of an automated module assembly process with low usage of volatile organic compounds and hazardous materials. The results of the program were as follows: (1) Manufacturing improvements have led to dramatic improvements in performance, quality, durability and cost. (2) The first ever ethylene vinyl acetate encapsulation system for photovoltaic concentrators was developed, thereby eliminating volatile organic compounds and hazardous materials in the encapsulation process. (3) An in-house extrusion system was developed that produces the highest quality cell assemblies at low labor cost. (4) An advanced automated cell assembly station was developed that produces quality cell assemblies at low labor cost. (5) Solvents have been eliminated in the module assembly eliminating volatile organic compounds and hazardous materials. (6) Roll formed steel panel frame members have been introduced to production that have dramatically reduced cost. (7) A snap-together module assembly has been developed that provides low-cost field assembly of components and thereby also greatly reduced shipping cost. The Powergrid has the potential to be very low cost in the short term. The PVI PVMaT program should allow PVI to reach the cost goals set by the company. This, in turn, will allow PVI to become a substantial player in the PV market and will allow the DOE goals of increased application of PV to become a reality