A low cost additive-free acid texturing process for large area commercial diamond-wire-sawn multicrystalline silicon solar cells.

• An additive-free acid texturing process is demonstrated for the DWS multi-crystalline silicon wafers in solar cell manufacturing industry. • These textured wafers have similar optoelectronic and electrical properties as that of industrial additive-based acid textured DWS wafers. • The reported additive-free textured cells have similar batch average efficiency to that of the additive-based acid textured cells in industrial production. • Further optimization of fabrication conditions, our proposed textured wafers will possibly increase the cell efficiency. • Proposed texturing scheme cut-down nearly 60% of chemical cost of additive-based acid texturing process presently used in industry. Diamond-wire-sawing (DWS) technique allows slicing of silicon ingots to produce wafers at cheaper price due to its reduced kerf-loss and increased cutting rate. However, there is no cost-effective and industrially viable method available for texturing DWS wafers, especially for multicrystalline silicon (mc-Si) wafers. Currently additive-based acid texturing process is availed by PV manufacturing units for texturing DWS mc-Si wafers. An additive-free, low cost and energy-efficient acid texturing process is demonstrated for DWS mc-Si wafers in industrial production line. Nearly 10% absolute reduction in weighted average reflectance values (WAR) are noticed for the newly textured wafers from that of as-cut DWS mc-Si wafers and the WAR values are comparable to that of existing additive-based acid textured mc-Si wafers. An absolute reduction in emitter saturation current density by ~ 17 fA - cm - 2 and improved implied open circuit voltage of ~ 5 mV (absolute) are reported for lifetime sample fabricated using newly textured wafers when compared to the additive-based acid textured lifetime samples. An impressive batch average efficiencies of 18.20% and 18.24% are achieved for the additive-free and existing additive-based acid textured mc-Si cells, respectively. Detailed analysis conclude that ~ 1.5% (relative) enhancement in short circuit current density can be achieved by further process optimization. Cost analysis indicates that 60% of the chemical cost involved the texturing process can be cut down by replacing the existing additive-based acid process with the new method using the same process equipment. Hence, the texturing process presented has great potential for producing large area high efficiency mc-Si cells favoring cost considerations without compromising performance. [ABSTRACT FROM AUTHOR]