A comparative study of model fitting for estimating the overall efficiency of grid-connected photovoltaic inverters

Abstract

Determining the static overall efficiency of inverters is sometimes necessary for control o design purposes. As getting this information from the manufacturers’ datasheets or certified laboratories might not be always viable, this paper addresses its estimation from direct measurements under actual operating conditions. Particularly, the Sandia Inverter Model has been taken as a paradigm of methodology and adapted to deal with the available data for an office building’s photovoltaic system over the 2013- 2017 period. Two unidimensional and two bidimensional models have been selected and compared to assess their goodness of fit on three inverters of the same kind of which the system consists. The best-case scenario corresponds to an exponential curve fitting, in which the R-square value increases over 0.95, outperforming the other models.