Differential diffusion charge redistribution for photovoltaic cell-level power balancing

Mismatch loss remains an important issue to address in PV systems, and many power electronic solutions have been proposed to recover these losses. However, conventional power electronics for solar power optimization often have to make tradeoffs among conversion efficiency, optimization granularity, and overall system cost. This paper presents a cell-level power balancing scheme that breaks the existing design paradigm. The proposed architecture simultaneously achieves maximum power point tracking without any external passive components at the cell-level, and maintains differential power processing with zero insertion loss. This is accomplished by leveraging the recently proposed diffusion charge redistribution technique, taking advantage of the readily available diffusion capacitance of solar cells to perform power balancing rather than relying on adding costly energy storage components. Furthermore, a dual current inverter interface is introduced to avoid processing common-mode generated power in order to minimize overall conversion loss. Significant boost in overall system efficiency is achieved under both matched and partial shading conditions. Simulation results are included to demonstrate the feasibility and benefit of this approach.