Every figure on this site is computed from a named source, or it is not published
Solar and battery savings calculator
Most people with solar have never checked what it produces or what they are paid for it. Work out both from published yield data, in your own currency, and find out whether a battery is worth buying, including when it is not.
What your solar is worth
Six questions, about two minutes. Your figures update as you go.
Where are the panels?
Where are the panels?
This sets the sunlight figures for your part of the country. It is not stored unless you ask us to contact you.
How big is the array?
How do the panels sit on the roof?
How much electricity do you use a year?
What are you paid for the electricity you export?
Are you considering a home battery?
How the calculator works
- 01
Tell us about your roof
Postcode, array size, orientation and pitch. If you do not know your kWp, the panel count gets us close enough. It is on your installation certificate either way.
- 02
Tell us what you use and what you are paid
Annual consumption from your statement, and your Smart Export Guarantee rate. If you have never checked your export rate, we assume the legacy rate a household lands on by never having chosen, which is the cautious assumption.
- 03
Read the range, not a single number
You get an expected figure and the floor the model stays above in nine years out of ten. If a battery will not pay for itself on your numbers, the page says so plainly.
Every figure comes from our calculation engine rather than from your browser, so the number you see here is the same one that appears on an installer’s report. How we work it out.
Common questions
- Do I need to give an email address to see my result?
- No. The calculator shows your full result before asking for anything: the expected figure, the lower bound, the payback period and the verdict. The email field appears after the result and is entirely optional.
- What do I need before I start?
- Your postcode, roughly how big your solar array is in kWp or how many panels you have, your annual electricity consumption in kWh from your statement, and your Smart Export Guarantee rate if you know it. If you do not know your export rate we assume a cautious legacy figure rather than a flattering one.
- How accurate is the calculation?
- The figures are modelled rather than measured: yields come from simulated weather rather than readings from your roof. That is why we publish a range with a stated lower bound instead of a single number, and why our method page sets out what we have not yet validated.
- Why does the calculator show a range instead of one number?
- Because a single figure implies a precision no yield model has. Weather varies year to year, tariffs move, and household consumption is never exactly what a profile says. The lower bound is the level the model stays above in nine out of ten simulated years, which is the number worth planning against.
- Will it tell me if a battery is a bad idea?
- Yes. Where the modelled payback runs past the battery warranty, the result says plainly that it does not pay for itself and shows the payback period alongside it. That verdict is not softened and it is not a negotiating position.