Electrical question No.26 – Effect of temperature on voltage

An ideal solar cell may be modelled by a current source in parallel with a diode; in practice no solar cell is ideal, so a shunt resistance and a series resistance component are added to the model. The resulting equivalent circuit of a solar cell is shown on the left. Also shown, on the right, is the schematic representation of a solar cell for use in circuit diagrams. By the Shockley diode equation, the current diverted through the diode is: where I₀ = reverse saturation current n = diode ideality factor q = elementary charge k = Boltzmann’s constant T = absolute temperature Temperature affects the characteristic equation in two ways: directly, via T in the exponential term, and indirectly via its effect on I0. The net effect is to reduce V_OC linearly with increasing temperature. The magnitude of this reduction is inversely proportional to V_OC; that is, cells with higher values of V_OC suffer smaller reductions in voltage with increasing temperature.