The conversion efficiency of a solar cell is measured as the ratio of input energy (radiant energy) to output energy (electrical energy). The efficiency of solar cells has come a long way since Edmund Becqueral discovered the photovoltaic effect in 1839. Present research is proceeding at a fast clip to push the efficiencies up to 30% and beyond.
The efficiency of a solar cell largely depends on its spectral response. The wider the spectrum of light that the cell can respond to (the spectral response), the more power is generated. Research is ongoing to develop techniques and materials that can use more of the light spectrum and thus generate more power from each photovoltaic cell.
The reflectivity of the cell surface and the amount of light blocked by the sur- face electrodes on the front of the cell also affect the efficiency of solar cells. Anti-reflective coatings on cells and the use of thin electrodes on the surface of cell faces help to reduce this loss of photonic stimulation.
Another factor in cell efficiency is the operating temperature of the cell. The hotter a cell gets, the less current it produces. Inherently, solar cells in use get hot, so it is impor tant to have them mounted in such a way that they are cooled as much as possible to keep current production at its maximum.
Silicon is the most widely used material for solar cells today, though this is changing as thin film amorphous technologies are achieving greater efficiencies using materials such as gallium arsenide, cadmium telluride and copper indium diselenide.
