Solar Diverter vs EV Charger: Best Value in 2026? (UK)
If you already own a hot-water cylinder, a solar diverter pays back fastest — typically 2–3 years on a 4kWp PV system. If you own an EV, a smart charger pays back in 1–2 years on a typical off-peak tariff. Solar diverters cost £300–£650 fitted and save up to £270/year. Smart EV chargers cost £700–£2,375 fitted and save £500+/year on Intelligent Octopus, Cosy or similar off-peak tariffs.
Solar diverter vs EV charger — side by side (2026 UK)
The headline numbers in plain English: a solar diverter (Eddi, Solic 200, iBoost+ or similar) sends surplus PV electricity to your immersion heater, displacing gas or grid electricity used for hot water. A smart EV charger (Zappi, Ohme, Andersen, Wallbox or similar) draws cheap off-peak power overnight (5–9p/kWh) instead of standard rate (24–30p/kWh) to fill your car. Both unlock value, but in very different ways.
Upfront cost comparison
Solar diverter: The unit alone runs £180–£450 (myenergi Eddi £329 RRP). Installation by a qualified electrician adds £120–£200 — total £300–£650 fitted. Smart EV charger: Unit £300–£1,200 depending on tethered/untethered and brand. Installation labour £400–£1,175 depending on distance from consumer unit and supply upgrade needs — total £700–£2,375 fitted. OZEV grant (£350) for flats, renters and landlords only since 2022.
Annual savings comparison
Solar diverter savings: A 4kWp PV system in central England exports roughly 1,300–1,700 kWh/year if you have no battery. A diverter captures 60–85% of that, displacing gas at 6–7p/kWh or grid at 28p/kWh. Annual savings: £100–£270 (higher for households with electric immersion as primary water-heating). EV charger savings: Charging 8,000 EV miles/year (~2,300 kWh) on Intelligent Octopus at 7p/kWh vs flat tariff at 27p/kWh = £460/year saved. Higher-mileage drivers (15,000+ miles) save £800–£1,000/year.
Payback period
Solar diverter: 2–3 years for households with PV and gas hot water; 1–2 years for fully electric hot water (immersion or heat pump cylinder). EV charger: 1–2 years for typical 8,000-mile drivers on off-peak tariffs; under 1 year for high-mileage households. The EV charger has the faster payback per pound spent if you already drive an EV.
Which to fit first?
If you have both an EV and PV/hot-water cylinder: fit the EV charger first — faster payback and bigger annual savings. Then add the diverter for incremental gain. If you have no EV but do have PV and a hot-water cylinder: the diverter is the cheapest way to monetise surplus generation, especially if export tariff is sub-15p. If you have no PV but do drive an EV: smart EV charger is the obvious win; a diverter without solar makes no sense. Heat pump owners with hot-water cylinders should consider a diverter to use surplus PV for the cylinder — it stacks well with low-temperature tariffs.
How to choose step by step
1. Map your home energy use
List: EV (yes/no, annual miles), PV system (kWp, export tariff), hot water (gas combi vs cylinder vs heat pump), heat (gas vs heat pump).
2. Run the payback numbers
EV charger wins on payback for EV drivers; diverter wins for non-EV households with PV and a cylinder.
3. Get OZEV-approved or MCS-registered installer
EV chargers need a Part-P qualified electrician registered with OZEV. Diverters need a NICEIC/NAPIT electrician familiar with G98/G99 export limits.
4. Compare three quotes on the same scope
Quotes should specify: unit make/model, cable run length, supply upgrade if needed, smart-app features, and warranty.
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