GaAs solar cells for Indoor Light Harvesting

GaAs solar cells are the highest efficiency single-junction photovoltaic technology. Their wide bandgap lends them to efficient conversion of indoor light. In this paper GaAs solar cells are experimentally compared to Dye Sensitised solar cells, traditionally used for indoor light harvesting. The power density of GaAs solar cells was found to be over 3x greater than DSSC modules under indoor light levels. A credit card sized GaAs cell can provide 0.67 mW or 4 mW to a wireless sensor node in a dimly lit corridor (~200 lux) or well-lit office space (~1000 lux) respectively. A near linear relationship is measured between the open-circuit and maximum power voltages of GaAs solar cells at low light levels allowing their use with power conditioning circuits (MPPT tracking) based on the fractional-voltage method.