Planning tool
Solar and battery payback calculator
Work out what solar panels and a battery save each year, and how long they take to pay back, using today’s Octopus import and export rates for your region.
Today in London: Flexible Octopus import 26.60p/kWh, Outgoing Octopus export 12.00p/kWh.
Your estimate
- Yearly value of your panels
- £624.34
- Simple payback
- 11.2 years
Filling in the numbers
Your installer’s quote should give expected yearly generation. Without a battery, homes that are empty during the day use less of their generation directly; a battery lets you use more of it in the evening. For the battery shift, a rough figure is the battery’s usable capacity multiplied by the number of days a year it fills from solar.
What the estimate leaves out
This is a simple first-year estimate. It ignores future price changes, panel degradation, battery losses, maintenance, inverter replacement and the cost of borrowing. It prices self-use at Flexible Octopus and export at flat Outgoing Octopus; on a smart tariff such as Flux or Intelligent Go the figures differ. See the solar tariff guide and export rates by region.