EFG technology and diagnostic R&D for large-scale PV manufacturing

We report here on R&D efforts on technology being developed for processing cells and modules based on silicon ribbon wafers produced by the edge-defined film-fed growth (EFG) technique. Manufacturing of EFG wafers has matured at RWE SCHOTT Solar, Inc. (RSSI) during the past 10 years and ribbon growth capacity has expanded to over 40 MW. We are developing cell manufacturing methods for EFG wafers with areas up to 12.5 cm × 12.5 cm, and discuss R&D on implementing process control and diagnostics improvements for a 12 MW cell line in Billerica which is currently being upgraded in capacity. Current priorities in our NREL program also examined include: developing a computer-controlled maintenance management system, automating EFG wafer and cell production, diagnostics and sensor development in wafer production, evaluating improved laser cutting technology, and improving properties of 250 micron thick large area EFG wafers.