Analysis of the EWT-DGB solar cell at low and medium concentration and comparison with a PESC architecture

Abstract

Silicon represents an interesting material to fabricate low-cost and relatively simple and high-efficient solar cells in the low and medium concentration range. In this paper, we discuss a novel cell scheme conceived for concentrating photovoltaic, named emitter wrap through with deep grooved base (EWT-DGB), and compare it with the simpler passivated emitter solar cell. Both cells have been fabricated by means of a complementary metal-oxide-semiconductor-compatible process in our laboratory. The experimental characterization of both cells is reported in the range 1-200 suns in terms of conversion efficiency, open circuit voltage, short circuit current density and fill factor. In particular, for the EWT-DGB solar cells, we obtain an encouraging 21.4% maximum conversion efficiency at 44 suns. By using a calibrated finite-element numerical electro-optical simulation tool, validated by a comparison with experimental data, we study the potentials of the two architectures for concentrated light conditions considering possible realistic improvements with respect to the fabricated devices. We compare the solar cell figures of merit with those of the state-of-the-art silicon back-contact back-junction solar cell holding the conversion efficiency record for concentrator photovoltaic silicon. Simulation results predict a 24.8% efficiency at 50 suns for the EWT-DGB cell and up to 23.9% at 100 suns for the passivated emitter solar cell, thus confirming the good potential of the proposed architectures for low to medium light concentration. Finally, simulations are exploited to provide additional analysis of the EWT-DGB scheme under concentrated light.