The diurnal and seasonal changes in the solar spectrum affect the photovoltaic (PV) module performance. In this article, the transient solar spectrum was integrated with the thermal–electrical model of the PV module for precise estimation of diurnal and seasonal PV performance. The transient meteorological parameters were considered for determining the dynamic power output of the PV. The SMARTSv2.9.5, COMSOL Multiphysics, and MATLAB were used for modeling different sections and integrated throughout. The cell temperature and power output were obtained and experimentally validated for various seasons. The statistical errors, such as mean absolute error (MAE), mean relative error, and root-mean-square error (RMSE) values, and the coefficient of determination ( R 2 ) value were calculated for the developed model during various seasons. The RMSE of back surface temperature and power output from monocrystalline ranges from 1.67 to 2.59 °C and 1.83 to 2.92 W, respectively, and the same for polycrystalline PV module ranges from 1.93 to 2.29 °C and 1.70 to 3.63 W, respectively. The MAE of the I sc and V oc ranges between 0.10 and 0.29 A and 0.41 and 0.58 V, respectively, for monocrystalline, 0.13–0.43 A and 0.39–0.52 V, respectively, for polycrystalline PV modules. The present model is a simple integration and uses basic mathematical equations and parameters to predict the PV outputs.