Characterisation of n-type bifacial silicon PV modules

Bifacial PV modules have shown the potential to increase the performance of traditional photovoltaic module architectures using relatively conventional silicon manufacturing techniques. Bifacial modules can produce additional energy from the rear surface of the module, collecting not only light incident on the front surface but also sunlight scattered or reflected from the ground or environment onto the rear surface. To assess their performance and quality, PV modules are characterized using international standards to rate the modules in terms of output power and efficiency. However, at present, no specific standards exist for bifacial modules. Furthermore, these modules are often characterized by a high efficiency and an increased capacitance and the measurement with standard pulsed solar simulators may be affected by strong measurement artefacts resulting in increased or reduced maximum power. This work presents the indoor characterisation of bifacial c-Si PV modules under varying irradiance levels using different methods such as a single-sweep flash simulator, the so-called multi-flash (MF) method and a steady state sun simulator for the accurate measurement of the module parameters. The effect of different rear surface coverings, from matt black painted wood to gloss white card and the differences among the characterisation method are also investigated.