Home battery ROI calculator
Estimate extra self-consumption from a battery and whether it pays back before reaching end of cycle life.
Your situation
Defaults are starting points from typical published ranges — never facts. Change any value that does not match your situation.
Estimate only. Based on the assumptions you entered. Get a site-specific survey before spending money.
Extra self-consumed
2,160 kWh/yr
Annual saving
€432
spread 0.200 €/kWh
Simple payback
13.9 years
Cycle life span
24.0 years
Formula with your numbers
throughput = 9.6 × 90/100 × 250 = 2,160.0 kWh/yr
extra_self_consumed = min(throughput, 2500) = 2,160.0
annual_saving = 2,160.0 × (0.28 − 0.08) = €432
payback = 6000 / annual_saving = 13.89 yr
Frequently asked questions
When does a home battery pay back?+
Usually when you currently export a lot of cheap solar and import expensive grid power later. The value is roughly the retail–export price spread times the extra kWh you can shift.
Why include round-trip efficiency?+
Not every kWh stored comes back out. Round-trip efficiency (often ~85–95%) reduces usable throughput and therefore savings.