The glasses that are used on Photovoltaic panels (PV), directly affect the output power performance of the PVs according to their ability to transmit the solar light, beside protection of the PV cells against environmental effects. Therefore, it can be said that they are among the most important parts of solar panels. In this study, it is aimed to investigate "the effects of different type of glasses having different characteristically properties" on the output power of solar panels. For this aim, two identical PV modules are obtained from the market. Consequently, the glass of one of the PV module is replaced with different type of glasses (Replaced using 3 different glasses) and the output power of the module is measured during experiments, by the help of a DC load that is connected at the output of the module. On the other hand, same load is connected to the output of the original module and the performances of each module are tested under same solar radiation conditions. Finally, the measured data are analyzed and the total efficiency lose are compared with the efficiency of the PV having original glass that was optimized to have high light transmit ability.