Investigated the synergetic effect of rooftop solar PV generation by residential prosumers on reducing substation transformer aging due to PEV. Quantification of substation transformer aging for internal combustion engine-based NHTS data compared to PEV driving data from CPEVS. Moreover, a comparison of the substation transformer aging is performed based on varying plug-in electric vehicle charging levels. Substation transformer LOL is at least 30% higher using PEV studies versus ICE vehicles at 0% PV penetration and twice as high at 100% PV penetration.