Energy is very important key to improve human life. Due to the global warming and pollution, the new energy source is developed. Photovoltaic is one of these sources that growth in recent decades and has several models. Using the practical and simple model to compare with other models is necessary, to this purpose in this paper at first the ideal model of photovoltaic is described then appropriate model by using MATLAB software is presented. On other hand knowing the effect of environment of PV characteristics to predict its behavior is important. These models included diode-(diodes), series resistor and source. The temperature and solar irradiation were inputs variable parameters and I-V and P-V characteristic were the outputs. At end, effect of each parameter is presented.