The efficiency basically describes the ratio between energy outputs and inputs. The higher the efficiency, the greater the capacity to convert solar radiation to electricity. The different types of efficiency are cell efficiency, module efficiency and system efficiency. In commercial mass production, a cell efficiency of up to 18.3% is currently obtained, depending on the technology that is used.

The module efficiency relates to the entire module surface and is therefore always slightly lower than the individual cell efficiency. This is partly due to the non-usable spaces between the arrays of solar cells in the module. The system efficiency relates to the complete solar installation. Here there is another drop compared with the module efficiency, which is due to conductance losses in the various wiring.