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. The domestic EV chargepoint grant rose to £500 per socket (75% of hardware and installation) in April 2026, up from £350 — but it stays limited to renters and flat owners with off-street parking, per the gov.uk chargepoint grant guidance; owner-occupiers of houses and anyone fitting a diverter still get no grant.
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.
Payback scenarios by household type
PV owner, gas hot water, no EV: the diverter is the only device that pays here. On a 4kWp array on a 12p SEG export tariff, sending 1,000–1,400 kWh a year to the immersion instead of exporting saves roughly £150–£220 against gas at 6–7p, so a fitted £300–£650 unit clears its cost in 2–4 years — our is a solar diverter worth it in 2026 guide works through the full sums. EV driver, no PV: only the charger helps; over 8,000 miles a year an off-peak tariff at 7p versus a 27p day rate saves about £460, so a £700–£1,500 fitted charger pays back inside two years — see our is an EV charger worth it in 2026 guide for a mileage-by-mileage breakdown. PV owner who also drives an EV: fit the charger first for the bigger, faster return, then add the diverter to mop up whatever surplus the car leaves — a myenergi Eddi and Zappi share generation data so the car takes priority and the tank gets the remainder. All-electric home (heat pump or immersion, no gas): the diverter's saving jumps because every diverted unit displaces 27p grid electricity rather than 7p gas, pushing annual savings toward £270–£320 and shortening payback to 1–2 years.
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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