Battery Payback Calculator

This calculator uses average Estonia Nord Pool prices (Jun 2025–Jun 2026) with seasonal price spreads and typical consumption/solar production profiles. The simulation models hourly arbitrage: charging the battery from solar or cheap grid hours and discharging/selling during expensive peak hours. For personalized results based on your actual 15-minute interval data, connect your Elering account in the dashboard.

The simulation runs through 13 months of 15-minute interval data. Solar excess charges the battery for free during the day's cheaper solar hours — when the price is high, solar exports directly to avoid efficiency losses. During expensive peak hours (above the daily median), the battery self-consumes to offset your usage (saving the full all-in price) and sells to the grid during the day's highest-price hours. On cloudy/winter days, the battery charges from the grid at the day's cheapest hours, but only when the expected discharge value × efficiency beats the charge cost by at least 20%. Without any consumption (pure grid arbitrage), every charge hour must be paired with a more expensive sell hour later the same day — days without a profitable pair stay idle instead of cycling at a loss. Grid selling earns only the electricity spot price (no grid fees), while buying costs the full all-in price (spot + grid + fees + VAT), so grid arbitrage requires large price swings to be profitable.