21.9% efficient silicon bifacial solar cells

This paper reports the efficiency of bifacial silicon solar cells and mini-modules fabricated at SunPower Corp. The best cell has AM1.5G front efficiency of 21.9% and rear efficiency of 13.9%. The mini-modules, each containing 20 bifacial cells, attain efficiency as high as the average efficiency of their individual cells. The best module has AM1.5G front efficiency of 20.66% and rear efficiency of 10.54%. Optical properties of the bifacial cells have also been measured and analyzed. The results show that bifacial cells, compared to monofacial cells, absorb less infrared light and thus they can operate at lower temperature in space.