Concentrating photovoltaic multijunction (CPVM) module electrical layout optimisation by a new theoretical and experimental “mismatch” analysis including series resistance effects

Abstract

A new theoretical and experimental ‘current mismatch’ analysis of CPVM modules, including series resistance effects, is proposed. It allows predicting the I–V curve and the maximum power point of the module, considering its series resistance value and a given mismatch condition, for all the possible circuital module topologies having a fixed number of Multi-junction (MJ) solar cells. The optimum module circuital layout can be determined considering the mismatched cells number, the mismatch distribution in the module, the current mismatch percent value related to each cell, the module series resistance value and the resistance value of cables connecting the module to the inverter. The new theoretical approach is validated on a 144 MJ solar cells Point-Focus module, of which, in order to experimentally simulate the mismatched conditions, some cells are on purpose blinded and the module experimental I–V curve detected. The experimental curves are successfully compared with the theoretical ones predicted by the modeling application. On the base of the theoretical mismatch analysis for modules consisting of only-one string with series-connected receivers, an original algorithm is developed to identify the current receiver's mismatch starting from any experimentally detected I–V curve, also for curves presenting many current steps.