Average Cost of a Solar Diverter Installation in 2026 UK
A solar diverter sends surplus solar electricity to your immersion heater instead of exporting it. In 2026 the fitted cost is £320–£700, with most installs landing at £450–£550. It only works if you have a hot water cylinder with an immersion heater — combi-boiler homes cannot use one.
Solar diverter costs — 2026 UK at a glance
- Fitted cost: £320–£700, typically £450–£550.
- Unit only: £180–£400 depending on brand and whether it has a display or app.
- Installation labour: £120–£300 for a half-day electrician visit.
- Annual saving: £90–£250 on water heating, depending on array size and usage.
- Requirement: a hot water cylinder with an immersion heater — combi boilers are not compatible.
Bottom line: if you already have solar and a cylinder, a diverter is one of the cheapest upgrades available and usually pays for itself in 2–5 years. If you are choosing between a diverter and a battery, the diverter is far cheaper but only offsets hot water.
What you actually pay for in 2026
Prices assume an existing solar PV system and an accessible cylinder. Adding a diverter at the same time as a new solar install usually costs less because the electrician is already on site.
When a solar diverter pays and when it doesn't
- Worth it: you have a hot water cylinder, a 4 kWp or larger array, and you are out during the day so most generation is currently exported.
- Marginal: your export tariff is generous — a strong Smart Export Guarantee rate narrows the gap between exporting and self-consuming.
- Not possible: you have a combi boiler with no cylinder, or a heat-pump cylinder with no immersion element.
- Diverter vs battery: a diverter is roughly a tenth of the price of a battery but only offsets water heating, not evening electricity use.
- Summer bias: most of the benefit lands April to September, when surplus generation is highest and heating demand is lowest.
Tip: check your current Smart Export Guarantee rate first. If you are on a high export tariff, the saving from self-consuming is the difference between your import and export rates — not the full import price.
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Frequently asked questions
GBP 320-700 fully installed, with most households paying GBP 450-550. The unit is GBP 180-400 and electrician labour is GBP 120-300 for roughly a half-day visit.
Typically GBP 90-250 a year on water heating. The saving depends on your array size, how much surplus you currently export, your import and export tariff rates, and your hot water usage pattern.
Usually 2-5 years. Payback is fastest for households with a 4 kWp or larger array, a well-insulated cylinder, and daytime occupancy low enough that most generation is currently exported.
Yes. A diverter works by sending surplus solar electricity to an immersion heater in a hot water cylinder. If you have a combi boiler with no cylinder, a diverter cannot be fitted.
They do different jobs. A diverter costs a fraction of a battery but only offsets water heating. A battery costs GBP 3,000-8,000 and offsets evening electricity across the whole home. Many households fit a diverter first and add a battery later.
No. The work involves connecting to your consumer unit and fitting a current transformer on the incoming supply, which is notifiable electrical work. Use a qualified electrician, ideally one MCS-registered for solar.
Sources used in this guide
- MCS - Microgeneration Certification Scheme
- Ofgem - Smart Export Guarantee
- TrustMark - Government-endorsed quality scheme
Methodology: Cost ranges reflect quotes collected through the BestBuilders network and published trade pricing for Q3 2026 UK, excluding VAT relief cases. Regional variation of 20-35% applies in London and the South East. Last fact-checked: .