It is well known that accurate knowledge of photovoltaic cell parameters from the measured current-voltage characteristics is of vital importance for the quality control and the performance assessment of photovoltaic cells/modules. Although many attempts have been made so far for a thorough analysis of cell parameters, there are still significant discrepancies between the previously published results. In this regard, a detailed investigation of cell parameters through a comprehensive experimental and statistical work is important to elucidate the aforementioned contradictions. Therefore in the present work, effects of two main environmental factors on performance parameters of mono-crystalline and poly-crystalline silicon photovoltaic modules have been experimentally investigated. The experiments have been carried out under a calibrated solar simulator for various intensity levels and cell temperatures in the range 200500 W/m(2) and 15-60 degrees C, respectively. The results indicated that light intensity has a dominant effect on current parameters. Photocurrent, short circuit current and maximum current increase linearly with increasing intensity level. A new term, solar intensity coefficient, has been defined first time to characterize the solar radiation dependency of current parameters. On the other hand, it has been observed that cell temperature has a dramatic effect on voltage parameters. Open circuit voltage and maximum voltage considerably decrease with increasing cell temperature. Temperature coefficients of voltage parameters have been calculated for each case. Shunt resistance has also been found to be rather sensitive to the variations in cell temperature. Shunt conductance of photovoltaic modules has almost remained constant as light intensity level changed. A linear decrease of series resistance has been observed with increasing cell temperature. Thermodynamic performance assessment of photovoltaic modules has also been done in the study. (C) 2013 Elsevier Ltd. All rights reserved.