This paper presents a novel model to evaluate the electrical performance of a silicon photovoltaic (PV) module with respect to changes in main environmental parameters such as temperature and illumination intensity. A simple one-diode model is proposed to estimate the electrical parameters of PV module considering the series resistance and shunt conductance. Effects of PV module parameters on current-voltage characteristic curve are investigated. The proposed model also makes a thermodynamic assessment concerning the effects of environmental and electrical parameters on efficiency and maximum power output of the PV module. Kyocera KD205GH-2P205-W highefficiency multi-crystal PV module is used for model evaluation. Model results are compared with the manufacturer's data report and an excellent agreement is observed.