Impact of the bias on the temperature of silicon solar cells under operating conditions

Currently, the temperature of an illuminated solar cell is thought independent of its bias. This assumption allows the application of the principle of superposition. However, the temperature dependence of the solar cell with respect to its bias can be shown to induce a departure from the principle of superposition with the aid of rigorous electro-thermo-radiative simulations. This dependence limits the validity of the principle of superposition to solar cell where the temperature is controlled. We further demonstrate that the temperature at the maximum power point is close to the lowest temperature of the cell as a function of the bias. In order to be as close as possible to the operating conditions of a solar cell, it is suggested to determine the nominal operating cell temperature at the maximum power point instead of the open circuit conditions as defined in the ASTM standard and to optimize solar cells for the temperature at the maximum power point.