A Photovoltaic module efficiency is mainly depend on the ambient temperature, module temperature, incoming solar radiation intensity and photovoltaic material composition. In the present work, the effect of module temperature on the photovoltaic (PV) panel efficiency was investigated experimentally. Incoming solar radiation on the PV surface (I), ambient temperature of the panel (Ta), back surface temperature of the panel (Tp), voltage and current are the main parameters measured during the experiments. In the experimental system the area that PV module placed have been adjusted four different ambient air temperature as 10, 20, 30 and 40 degrees C. PV module efficiencies are calculated with using obtained experimental data. According to the computations the module efficiency was 12.07% for the 14.9 degrees C of Tp while it was found as 10.7% for the 51.3 degrees C of Tp. It was observed that increasing of PV module temperature decreases efficiency.