Energy Yield Enhancement by Switched Capacitor Converter-Based Differential Power Processing Converter Utilizing Diffusion Capacitance of Curved Photovoltaic Panels

Uneven irradiance on curved photovoltaic (PV) panels consisting of multiple substrings connected in series causes a significant energy yield reduction because of mismatched substring characteristics. Switched capacitor converter (SCC)-based differential power processing (DPP) converters utilizing diffusion capacitance of PV cells have been proposed in previous works to prevent the characteristic mismatch issue. However, parasitic inductances of cells and DPP converters hinder charge shuttling among cells, resulting in a reduced energy yield of PV panels. This paper examines the energy yield enhancement of the SCC-DPP converter by adding smoothing capacitors to mitigate the negative influence of parasitic inductances. The relationship between the overall energy yield efficiency and substring structure is also investigated. A dc equivalent circuit of the DPP converter is derived for these examinations. Experimental field tests and simulation using the dc equivalent circuit were performed for the 24-cell PV module under various irradiance conditions. The experimental and simulation results agree well, and both results demonstrate the added smoothing capacitors improved the overall energy yield efficiency by several percentage points. Furthermore, the analytical results suggest the optimal substring structure, which maximizes the annual energy yield, varies depending on season and time.