A Diode-Aware Model of PV Modules from Datasheet Specifications

Semi-empirical models of photovoltaic (PV) modules based only on datasheet information are popular in electrical energy systems (EES) simulation because they can be built without measurements and allow quick exploration of alternative devices. One key limitation of these models, however, is the fact that they cannot model the presence of bypass diodes, which are inserted across a set of series-connected cells in a PV module to mitigate the impact of partial shading; datasheet information refer in fact to the operations of the module under uniform irradiance. Neglecting the effect of bypass diodes may incur in significant underestimation of the extracted power. This paper proposes a semi-empirical model for a PV module, that, by taking into account the only available information about bypass diodes in a datasheet, i.e., its number, by a first downscaling the model to a single PV cell and a subsequent upscaling to the level of a substring and of a module, allows to take into accout the diode effect as much accurately as allowed by the datasheet information. Experimental results show that, in a typical PV array on a roof, using a diode-agnostic model can signifantly underestimate the output power production.