Nowadays, there are several difficulties are met in the selection of appropriate conditions, place of use, and purpose of photovoltaic (PV) systems. The reason is that electrical power output of PV system shows a non-linear variation, unlike other applications, depending on the internal resistance of electrical devices (loads) as well as radiation intensity and environmental temperature. Therefore, electrical characteristics of PV panel-load must be evaluated together for correct optimization. In this study, running an electrical device having optimized curve of linear load on a monthly basis of a panel was analyzed. At the same time, surface temperature of the panel, panel inclination angle and value of the load that concerning electrical load impact on power output of PV panels was examined experimentally and theoretically. © 2012 IEEE.