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Battery Calculator

Battery Payback Calculator

Enter your solar panel size, yearly consumption, and battery details to see estimated savings and payback period.

Yearly Savings

€383

Monthly Savings

€32

Payback Period

13.0 years

Your Setup

10 kWp
0 kWp30 kWp
10,000 kWh
1,00050,000 kWh

Battery Configuration

10 kWh
150 kWh
€5,000
€500€30k
90%
70%98%

Estimated Savings

€49
Jan
€34
Feb
€37
Mar
€23
Apr
€24
May
€21
Jun
€22
Jul
€24
Aug
€27
Sep
€23
Oct
€42
Nov
€56
Dec

Yearly Savings

€383

Monthly Savings

€32

Payback Period

13.0y

Solar

1722 kWh

Grid

1080 kWh

Used

1541 kWh

Sold

1249 kWh

This calculator uses average Estonian Nord Pool prices (Mar 2025–Mar 2026) and typical consumption/solar production profiles. For personalized results based on your actual 15-minute interval data, connect your Elering account in the dashboard.

How we calculate

The simulation runs through 13 months of 15-minute interval data. Solar excess charges the battery for free when spot price is below the daily median β€” when price is high, solar exports directly to avoid efficiency losses. During expensive peak hours (above daily median), the battery self-consumes to offset your usage (saving the full all-in price) and may sell to the grid if the spot price is at least 3Γ— the day's cheapest spot price. On cloudy/winter days, the battery charges from the grid at cheap off-peak rates, but only when the expected peak all-in price Γ— efficiency exceeds the charge cost. 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.

Start saving on your electricity bill

Create a free Elewatt account to set up smart schedules for your devices, track your consumption, and see personalized savings based on your actual electricity data.

Frequently Asked Questions