Researchers from Singapore's A*STAR institute discovered that graphene outperforms ITO as solar panels transparent electrodes. The researchers say that stacking four graphene sheets is the best method - as more graphene sheets decrease the resistance but blocks more light.
A single graphene sheets blocks less than 3% of light which means more light can reach the solar panel. Graphene's efficiency as a solar panel electrode depends on the type of light absorbed by the panel. For solar panels that absorb near-infrared light graphene is only slightly less effective than ITO, while graphene would be ideally suited to photovoltaic cells with a very broad absorption range, such as a recently developed organic solar cell that can harvest light from 350 to 850 nanometers.