Industrial Cost Effective N-Pasha Solar Cells with >20% Cell Efficiency

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