The Impact of Virtual Net-Metering Allocation on Self-Consumption Ratios in Multi-Dwelling Building Photovoltaic Systems

Collective self-consumption (CSC) in multi-dwelling buildings (MDBs) became feasible in Finland following EU regulations through the Credit Calculation Model (CCM) with virtual net-metering integrated into the national Datahub system. This study evaluates self-consumption ratios (SCR) under three metering configurations—common-area consumption (CC), CCM, and behind-the-meter (BM)—using hourly consumption data (2019–2021) from 32 MDBs (14–168 apartments, built 1960s–2020s) in Pirkanmaa region. PV production was simulated with PVGIS-SARAH3 for 10–60 kWp systems at south, 45° east, and 45° west orientations (18° tilt). The goal was to quantify SCR gains from adopting CCM and to compare BM and CCM to guide simulations when only aggregated building-level data are available. CCM increased SCR by approximately 30% for 20–60 kWp systems compared with CC. BM–CCM differences averaged 6 to 9% (range 0 to 19.5%) for 20–60 kWp systems. West-oriented arrays achieved slightly higher SCR due to better load alignment. These findings provide quantitative tools for DSOs, housing companies, and PV designers to improve SCR estimation and PV project viability in MDBs. While results are based on Pirkanmaa, they offer guidance for broader contexts until higher-resolution metering and flexible loads are incorporated in future studies.