Solar has got noticeably cheaper over the last few years — prices are down roughly 30% since 2021 — and the combination of 0% VAT and export payments makes the payback maths more straightforward than it used to be. Here's what a system actually costs and how long it takes to pay for itself.
Adding a battery (typically 5–10kWh) costs a further £3,000–£6,000, and lets you use more of the electricity you generate rather than exporting it at a lower rate. 0% VAT applies to both panels and batteries, worth £1,000–£3,000 depending on system size, already reflected in the figures above — though this relief is due to end on 31 March 2027, after which it reverts to 5%.
Most solar-only systems pay back in 7–12 years, largely driven by how much of your own generation you use during the day rather than export — households with daytime electricity use (working from home, an EV charging at home, appliances run during the day) tend to see faster payback than those out at work all day.
Adding a battery increases how much of your generation you use at home (from roughly 40–50% self-consumption up to 70–80%), but the battery itself typically takes 10–14 years to pay back on its own — so it improves your overall energy independence more than it improves the headline payback number. Worth deciding based on what you actually want from the system, not just the fastest return.
Every large electricity supplier has to offer an SEG export tariff. Rates vary a lot — from around 4p/kWh up to 15p/kWh on the better fixed tariffs, with some time-of-use tariffs paying considerably more at peak export times. A typical 4kW system exports around half its generation, earning roughly £100–£300 a year depending on the tariff you're on. You'll need a smart meter that can record half-hourly export readings before a supplier will pay out.
Solar and home EV charging pair unusually well: charging during daylight hours means driving on electricity you've already generated for free, rather than exporting it at a lower rate or buying it back from the grid in the evening. If an electric car is on your radar at all, it's worth planning the two together rather than as separate decisions — some installers can size a system with that in mind from the start.
Most London homes can install solar as permitted development — no planning application needed — provided panels don't project more than roughly 0.2m from the roof, the building isn't listed, and it's not in a World Heritage Site. Conservation areas add some conditions around street-facing installations. Whether you actually need permission depends on whether an Article 4 direction covers your address — see the borough-by-borough comparison for what applies where you live.
Separately from planning permission, your installer also has to notify or apply to your local electricity network operator (DNO) before you can export power. Most homes clear this easily: a standard single-phase inverter up to 3.68kW only needs a simple after-the-fact notification (G98), with no wait. Larger systems — a 5kW or 6kW inverter, which is typical for the detached-home figures above — usually need G99 approval instead, submitted before installation, which can take 6–16 weeks depending on your network operator and local grid capacity.
Figures above are 2026 UK averages; your actual quote depends on roof size, orientation, shading and your chosen installer and tariff.