Accurate and reliable modelling of photovoltaic (PV) modules is necessary for design and performance estimation of PV systems. Manufacturers of PV modules usually provide some basic electrical parameters specified at only one single operating condition, which is commonly known as standard test conditions (STCs). However, PV systems operate over a wide range of outdoor conditions, and the manufacturers' reports do not cover sufficient information about how the PV modules react with respect to changes in the two most important environment-oriented conditions, which are solar intensity and operating cell temperature. In this respect, an accurate and reliable tool is required by designers to predict electrical characteristics and thermodynamic performance parameters of PV modules. Therefore in this research, a novel mathematical model is developed to determine solar intensity and cell temperature dependency of PV module parameters and thermodynamic efficiency figures. A simple one-diode model is proposed considering series resistance and shunt conductance. Mitsubishi PV-UJ225GA6 225 W polycrystalline silicon PV module and Kyocera K121205GH-2P 205 W multicrystal PV module are utilised for model assessment. Model results are compared with environmental chamber tests and manufacturers' performance reports, and a very good agreement is achieved. (C) 2017 Elsevier Ltd. All rights reserved.