Partial Shading Mitigation in Photovoltaic Arrays using Shade Dispenser Technique

摘要

Partial Shading (PS) critically reduces the maximum power extractable from a photovoltaic (PV) array, decreasing its efficiency, and creating multiple local peaks (LP) in the characteristic P-V curve of the array. Currently, the electrical interconnection that minimizes these losses is the Total Cross Tied (TCT), where each panel in a string is connected in parallel to all the other panels in the same row, creating an electrical matrix connection. Although the TCT connection partially solves the problem, it is still sensitive to several shaded panels on the same row constraining the current. In this paper, a new method is presented to reduce the consequences of PS by optimally rearranging the electrical connections in such a way that the shadow is distributed through the array. The proposed method is dubbed "Shade Dispenser" (SD), as it takes a physical shade covering adjacent modules and electrically distributes it minimizing the occurrence of the same-row shades. The physical separation of electrically connected PV panels comes at a cost: it increases the wiring cost and power losses of the array. This trade-off is explored in this paper, outlining the solution for each array size. As a result, this technique represents a reduction in the effects of PS while minimizing wiring losses and costs. The performance of the system is investigated under different shading patterns and compared with the most efficient existing interconnections. Simulation results confirm that not only is the efficiency of the SD strategy higher, but the payback time for overhead wiring cost is lower. Moreover, this method diminishes the number of LPs in the P-V curve of the array.