Measuring changes in temperature coefficients is an effective way to estimate the performance of a solar cell. We investigated changes in the temperature coefficients of the I-V characteristics of amorphous silicon (a-Si) solar cells subjected to light degradation and recovery. There is a good correlation between change in the temperature coefficient (Psi) and the degradation/recovery state of a cell's conversion efficiency (eta). This relationship can be expressed by Psi (eta) = -0.0052 Delta eta - 0.45. Therefore, the temperature coefficient corresponding to the degradation/recovery state can be estimated.