Integrated power electronics for photovoltaic applications has attracted increasing interest, due to the possibility of having grid-connected photovoltaic modules with independent maximum power point tracking and high reliability. In this paper, a single-phase Current Source Inverter (CSI) is discussed for a photovoltaic application. The basic CSI topology will be explained for the sake of completeness, highlighting its main features and analyzing the ground leakage current problem, an important benchmark for photovoltaic application. A novel topology, called CSI5, is proposed in this work. The main feature is the presence of additional switches for ground leakage current reduction. The performance of the proposed topology is assessed by numerical simulation, and the experimental results confirm that this solution is able to strongly reduce the ground leakage current and conduction power losses.