Rooftop solar – the big one.

Two bits of officialdom, both smaller than they sound. Planning: most homes don't need permission – rooftop solar counts as 'permitted development' – unless the building is listed or you're in a conservation area, in which case ring the council before the scaffolding does. The grid: your installer notifies your local network operator – the people who own the wires, not the people who send your bill. For a normal-sized system that's a form sent after the switch-on; for a big one it needs sign-off first. Either way, it's the installer's job. If they try to make it yours, find a better installer.

Two ways. First: every unit you use yourself is a unit you don't buy at full price – about 26p as we write. Second: whatever you don't use is sold to your supplier for rather less. And there's the rub. A typical household only uses a fifth to a third of what its roof makes, because the roof does its best work at noon and you're at work. The rest goes out at the export rate, and the gap between a lazy export tariff and a good one is the difference between payback in 12 years and payback in 17. It's why our quiz asks whether anyone's home during the day. Installers rarely ask. It doesn't help the brochure.

That gap has a shape to it. Deals that pay you whatever you buy your electricity from cluster low, with a realistic ceiling around 12p. The ones paying much more require you to buy your electricity from the same company as well. Rates are set by suppliers, not regulated. The industry-wide data behind those figures covers April 2024 to March 2025, which makes it the oldest number on this site.

Oddly, yes. The more you use, the more of the roof's output you soak up at full value, and the bigger the system that makes sense in the first place. Solar is one of the few corners of life where being a heavy user counts in your favour. Enjoy it.

Homeowners with a roof pointing anywhere from east round to west, planning to stay put long enough for the maths to finish. Leaseholders: freeholder consent is a real hurdle, not a formality. Renters and flats: not this route – but keep reading, because two of the other three were built with you in mind.

There's no general solar grant for owner-occupiers (some low-income and local schemes exist) – but installing solar panels or a battery carries 0% VAT until 31 March 2027, after which it reverts to 5%, not 20%. VAT on your household electricity falls from 5% to 0% on 1 October 2026 and is set to run until 31 March 2027. And if you move before payback finishes, the panels stay with the house – they'll add something to the asking price, but nobody has ever got their money back at the removal van.