Monitoring of photovoltaic systems and evaluation of building energy self-consumption

The spread of nearly zero energy buildings (nZEB), promoted by the strategies set in the path of decarbonisation, has made the integration of renewable energy systems (RES) in buildings a common and strategic practice; in particular, they most involve small to medium building integrated photovoltaic (BIPV) systems coupled with heat pumps (HPs). One major challenge deals with the implementation of high self-consumption (SC) schemes for the energy produced on site, essential to carry on a wider implementation of photovoltaic systems. The present paper addresses the effect of different sizing strategies on the SC levels of 3 systems installed on traditional and nZEB houses, with a peak power between 3.12 kWp and 5.98 kWp. The systems have been monitored recording the various energy flows involved. Different optimization strategies have been tested with the purpose of minimizing the interaction with the grid, according to SC and self-sufficiency (SS) indexes. The aim is to provide design guidelines for the correct sizing in a bottom-up approach. Results underlined the fundamental role of storage technologies. Approximately 6 Wp/m2 assure an optimal energy employment without storage, with SS index below 35%: the integration of small storage, 3-7 kWh/kWp leads to SS and SC index above 60% and 88% respectively.