Buried‐contact silicon solar cells

Recent technological and commercial developments for the buried‐contact solar cell (BCSC) are reviwed. Four of the world's largest manufacturers have entered into manufacturing agreements, with a number of these taking advantage of the high‐efficiency capabilities of the large‐area BCSCs to produce cells for solar cars in the 1990 and 1993 World Solar Challenges and in the solar car race across the USA in 1993. Despite the efficiencies and commercial interest acheived by the conventional structure for the BCSC, a number of areas for improvement remain. In particular, the rear aluminium‐alloyed region limits the cell performance, and dislocation generation resulting from stresses at the silicon/silicon dioxide interface can also play a significant role in reducing efficiencies. Through the use of a photolithographically defined rear metal contact, efficiencies in excess of 21% and open‐circuit voltages as high as 693 mV for the hybrid BCSC have been demonstrated. the effect of the heavily diffused region beneath the metal contacts in the grooves is studied and its implications for the new generation of BCSCs with grooves on front and rear surfaces are considered. the economic and technological merits of a range of groove formation approaches are discussed, with a low‐cost, high‐throughput ganged dicing wheel saw with 35 wheels showing most promise.