Net metering interval impact on solar photovoltaic prosumer techno-economics in Finland

Residential solar photovoltaic systems, supported by net metering policy, are increasingly adopted in Finland for cost savings and environmental benefits. European Union Regulation 2017/2195 provides a transition from the 1-hour to 15-minute imbalance settlement period, with even finer resolutions being possible in the future. This paper examines the effects of 15- and 5-minute net metering intervals on the energy dynamics and economic outcomes of residential solar photovoltaic installations in Finland. With measured data from two prosumer households over three years, changes in imported energy, self-consumption, self-sufficiency, and value of solar photovoltaic for capacities from 1–20 kWp are analyzed. Findings show that for the 15-minute interval with a 5 kWp solar PV system capacity, annual grid imports increase by up to 110 kWh, self-sufficiency decreases by up to 1.4 percentage points, and monetary value decreases by up to € 11 for the capacities studied, with larger systems being less affected by the transition to a shorter metering interval. The 5-minute interval has a similar but slightly greater impact across all parameters. Moreover, Finland’s latest increase in value-added tax from 24 % to 25.5 % mitigates some financial losses of solar photovoltaic systems over shorter intervals. These findings offer insights for policymakers and prosumers navigating the evolving regulatory framework. • 5-min resolution measured data (2021–2023) from two prosumers in Finland were used. • 1–20 kWp solar PV systems were studied with 15- and 5-min net metering intervals. • Annual self-sufficiency reduces by up to 1.4 and 2.3 p.p. for 15- and 5-min intervals. • Annual value of solar PV decreases by up to €11 and €18 for 15- and 5-min intervals. • VAT increase reduces the negative economic impact of shorter metering intervals.