High Efficiency n-Type Metal-Wrap-Through Cells and Modules Using Industrial Processes

We report on our high efficiency n-type metal-wrap-through (MWT) cell and module technology. In this work, bifacial n-type MWT cells are produced by industrial processes in industrial full-scale and pilot-scale process equipment. N-type cells benefit from high recombination lifetime in the wafer and bifaciality. Also low-cost screen printed cells can yield over 20% efficiency. When combined with MWT technology, high-power back-contact modules result, which can employ very thin cells. We report a cell conversion efficiency of 20.5% (in-house measurement, certification pending), a significant gain compared to our earlier work. We will discuss performance of thin cells relative to thicker cells, comparing experimental results to modeling. Recently, two aspects of (mainly p-type) MWT technology have received increased attention: paste consumption and performance under reverse bias. We will discuss MWT paste consumption, showing how MWT technology, like multi-busbar technology, can support very low paste consumption. We also report on behavior of cells and modules under reverse bias. We also discuss the robustness of MWT technology to dissipation in hot spots under reverse bias. Finally, full-size modules have been made and cell-to-module ratios of the different I-V parameters were analysed. Modules from cells with average efficiency over 20% are pending. This work shows that low-cost n-type bifacial cells are suitable for industrial high efficiency back-contact technology.