Semi-automatic, volume production of silicon solar cells

Abstract

A low-cost, high-yield technology for producing single-crystal silicon solar cells at high volumes, and suitable for export to developing countries, is described. Thc proccss begins with 100 mm diamctcr as-sawn single-crystal p-type wafers with one primary flat. Processing steps include ctching and surfacc texturization, gaseous-source diffusion, plasma etching, and contacting via screen printing. Thc necessary adaptations of such standard processes as diffusion and plasma ctching to solarcell production are detailed. Ncw process devclopmcnts include a high-throughput surface-tcxturization technique, and automatic printing and firing of cell contacts.The technology, coupled with automated cquipmcnt dcvclopcd spccitically for the purpose, results in solar cells with an average efficiency greater than 1276, a yield cxcecding 95%. a tight statistical spread on parameters, and a wide tolerance to starting substrates (including the first 100 mm diameter wafers made in Canada). It is shown that with minor modifications, the present single shift 500 kWp (kilowatt peak) per year capacity technology can be readily expanded to 1 MWp per year, adapted to square and polycrystalline substrates, and efficiencies increased above 13%.