Comparison of 6 Photovoltaic Materials across 4 Orders of Magnitude of Intensity

A growing number of indoor microelectronic devices with low consumption (average power of mW) require a power source to which Photovoltaic modules can contribute. However, Photovoltaic devices are rated by their power output under Standard Test Conditions (STC), and the 1 sun (AM1.5, 1000W/m) intensity used for these tests is several orders of magnitude above what is found indoors. A study was undertaken to establish whether the performance of commercial and laboratory modules and cells were consistent with their STC results for 4 orders of magnitude of intensity below 1 sun. A detailed electrical characterisation was performed and the results presented here show that efficiency curves to have a bimodal pattern. The samples in one mode performed better at low light intensity which maybe due to the uniformly higher RP (around 10-10 ), the poorer mode samples having an RP around 10 . This suggests that STC are not representative over the range of intensity tested.