Industrially feasible PERC cells on diamond wire sawing multi-crystalline silicon wafers textured by RIE towards 21.62 efficiency

摘要

Cost reduction and cell efficiency improvement are the two keys to improving PV production processes. Diamond wire sawing (DWS) can significantly reduce the wafer processing cost and is gaining more market shares in multi-crystalline silicon (mc-Si) with advancements in texturing. Reaction ion etching (RIE) technology has been successfully applied to realize effective surface texturing in DWS mc-Si wafer regardless of grain orientations, with minimal chemical waste. Meanwhile, passivated emitter and rear cells (PERCs) and multi-busbar (MBB) are expected to be the mainstream cell technology with the largest gain in market share over the next few years, due to the high efficiency potential and compatibility with existing p-type materials and production lines. Combining the low cost material of DWS mc-Si with high efficiency structure of PERC with MBB, the final cell efficiency reached average of 21.29% with a batch size of 800 wafers and 21.62% for the best cell. Using 21% cells, the module average power reached 304W, and the cell to module (CTM) ratio reached 98.2%. It must be noted that the cell cost (per-watt) prepared by this route is actually decreased compared to the conventional technology of acidic texturing of DWS wafer with additives.