Research on the photovoltaic module efficiency in the south of Poland was conducted in 2009 in Stryszawa and afterwards in 2012 in Zabrze and Stryszawa. The research involved taking measurements of electric energy produced by systems of various power and technical solutions. The efficiency of PV modules was compared to the intensity of solar radiation in the locations under consideration and, thus, the efficiency of converting solar energy into electricity was determined. The research results facilitated designing and mounting of forty PV microsystems in Zabrze in 2014 (power from 2000 Wp to 3000 Wp). To the satisfaction of their users, they operate without failure.