Optimizing photovoltaic-battery systems for net-billing in Greece: Impact of building usage and pricing schemes

This study investigates the techno-economic performance of photovoltaic–battery (PVB) systems under the Greek net-billing framework. A simulation-based optimization framework evaluates how building usage and electricity tariff structure influence system sizing, self-consumption, and profitability. Three building types (residential, retail, and office) are analyzed under flat, dual-zone time-of-use (ToU), and real-time pricing (RTP) schemes, complemented by sensitivity analyses on price levels and volatility. The RTP scheme is derived from hourly wholesale market data, capturing realistic price variability in the Greek context. Building usage is found to be the dominant factor shaping PVB behavior. Residential buildings achieve the highest self-consumption (40–60%) with balanced PV-to-battery ratios (≈4 kW / 10 kWh), while retail buildings require larger systems (≈6 kW / 16–18 kWh) to meet daytime loads. Offices exhibit the lowest performance (5–30%) due to limited operation. Transitioning from a flat to a ToU tariff increases self-consumption by up to 20 percentage points, whereas RTP further enlarges storage capacities (up to 18 kWh) but yields only marginal self-consumption gains. Across all cases, payback periods remain within 6–8 years, as capacities adapt to maintain profitability under different tariffs. Sensitivity analyses show that PV sizing depends mainly on feed-in remuneration, while storage investment is driven by import prices and price volatility. As volatility decreases, battery capacity and profitability decline, while PV sizing remains stable. Overall, moderate temporal differentiation, such as refined ToU tariffs aligned with typical demand profiles, offers a balanced pathway for net-billing prosumers, enhancing flexibility and economic performance without the operational complexity of full RTP.