Improvements in Cast Polycrystalline Silicon PV Manufacturing Technology

The objectives of this NREL sponsored Photovoltaic Manufacturing Technology (PVMat) Program are to advance Solarex's cast polycrystalline silicon manufacturing technology, reduce module production cost in half, increase module performance and expand Solarex's commerical production capacity by a factor of three. To meet these objectives Solarex has: 1) Modified the casting process and stations andis now casting larger ingots in production; 2) Developed wire saw techology to cut wafers with less kerf loss and has transferred this technology to prodution; 3) Developed a laboratory process to increase cell efficiencies using back surface fields, mechanical texturing and gettering; 4) Modified the casting wires saw and cell processes in order to fabricate larger (15.2 cm by 15.2 cm) wafersand cells; 5) Improved the automated assembly of modules, reducing labor requirements and increasing throughput; and 6) Developed a frameless module with a lower cost backsheet and a simple, low cost electrical termination system. Solarex is now in the process of developing the equipment necessary for automated handling of thin 15.2 cm by 15.2 cm wafers and cells. This paper will discuss theefforts during the first two and a half years of the program.