The integration of solar photovoltaic systems into the grid presents itself with several novel issues that need to be solved before successful integration can be achieved. The problem of common-mode current, also known as leakage current, is one such concern when a trans-formerless system is preferred due to the benefits it offers. The issue of leakage current has been addressed in the past, but little to no effort has been made towards analyzing the effect of the non-linear behavior of the semiconductor switches used in power converter circuits. This introduces a gap between theoretical and practical results across all past studies. This paper proposes a mathematical analysis of the various non-linearities present in a transis-tor switch, which is a novel aspect of transformerless inverter circuit analysis and practical feasibility. The mathematical results define the effect of each non-linearity on the harmonic content and, hence, on the leakage current. A simulation-based study was also conducted, comparing the performance of the practical switch and the ideal switch based on common mode current magnitude and other parameters, including total harmonic distortion, rip-ple content, and root mean square values of the input and output currents and voltages. It was concluded based on simulation results that the leakage current in the presence of such non-linearities is 10 times higher and total harmonic distortion is 3 times higher than that in their absence for a 1kW system, and the rms values of the output voltage and current are also reduced. The findings suggest that the topologies developed for the mitigation of common mode currents must take into account the effect of non-linearities to be feasible for practical deployment.