Worked examples: Browse pre-calculated scenarios at solar-battery-vs-solar-only, then return here to replace the assumptions with your own figures.
How this calculator works
- Solar that would otherwise be exported already has a value, so the benefit of storing it is normally the avoided import price minus the export income you give up.
- The calculator combines that solar-shifting value with any additional tariff-arbitrage value you expect from charging cheaply and using the energy later.
- The extra battery cost is compared with the estimated annual benefit to produce a simple payback period.
What can change the result
- Export tariff value
- Grid import price
- How much surplus solar is actually available
- Battery losses, usable capacity and tariff shifting
How to read the result
High export rates can reduce the financial case for a battery even when self-consumption rises. Run the tool with realistic export income rather than treating exported solar as wasted energy.
A useful way to stress-test the answer is to change the most uncertain input by 10 to 20% and see whether your decision still looks sensible.
Worked example
If import costs 28p/kWh but export earns 15p/kWh, moving 1 kWh from export into later self-use is worth roughly the 13p gap before battery losses.
Frequently asked questions
Why separate solar and tariff shifting?
They are different sources of battery value.
Does this include backup power value?
No. This tool measures financial energy savings only.