INDUSTRIAL COST EFFECTIVE N-PASHA SOLAR CELLS WITH >20 EFFICIENCY

摘要

The n-Pasha cell is a bifacial solar cell concept with average efficiencies, depending on the materialquality, between 19.8% and 20%. Our process has been optimized to enable high efficiencies with narrow distributionon wafers from complete n-type ingots (2 to 10 -cm). This reduces the so-called electrical yield losses from a waferpoint of view, which is important since the wafer costs make up the largest part (~40%) of the total module costs forn-Pasha modules. We found that the costs/Wp for the 20% n-Pasha cell and module process are very similar to thoseof a 19% p-type cell, assuming the same absolute wafer and module manufacturing costs. In the paper the successfulimplementation of a reduction of >60% in BBr3 consumption, and a reduction of >50% in Ag consumption aredescribed, while keeping the n-Pasha cell efficiency at the same level. According to our calculations, the achievedreduction of the Ag and BBr3 consumption will lower the costs/Wp for n-Pasha modules below that of p-typemodules.For our current n-Pasha cells majority of the efficiency losses are due to recombination in the diffused layers andbelow the contact regions. By tuning both the emitter and BSF profile, an efficiency of 0.4% abs. was alreadyobtained, but, there is still room for improvements. Based on the simulations and experimental results, the pathtowards further optimization and efficiencies approaching 21% is discussed in more detail.