Solar-Powered EV Charger Installation

The reason to fit an EV charger through a solar specialist rather than a general electrician is one feature a standard unit cannot offer: surplus diversion. A solar-aware charger clamps a small current-transformer (CT) sensor around your incoming mains tails and reads, second by second, whether your roof is generating more than the house is using. When there is spare solar, it feeds that free power straight into the car instead of letting it flow to the grid.

Not all "solar" chargers do this the same way. The myenergi Zappi in ECO+ mode follows your surplus dynamically all the way down to a trickle — as a cloud passes and generation drops, it throttles the car rather than pulling from the grid, so you charge on 100% self-generated power. The Ohme range (Home Pro and ePod) offers Solar Match/Boost, but it only engages once there is roughly 1.44kW of surplus available and will top up from the grid to hold that minimum rate. For a Wiltshire home chasing maximum EV charging from solar, that difference matters.

The economics are compelling. Grid import sits around 27p/kWh in 2026, while the Smart Export Guarantee pays roughly 4–16p (a good tariff about 10.8p) for power you send back. Every kWh of midday sunshine you divert into the car instead of exporting is therefore worth around 16p to you — the gap between what you avoid importing and what you forgo in export. Over a year that turns a routine commute into near-free miles from April to September.

Seasonality is the honest caveat. A 4kWp array generates about 3,900kWh a year, heavily weighted to summer, so a Zappi will fill your car from the roof for much of spring and summer but lean on a cheap overnight tariff in winter. Pairing the charger with solar and battery storage closes that gap — stored daytime solar tops the car up in the evening. Our solar and EV charger guide walks through the full self-consumption picture for a typical household.

The most common upsell in EV charging is a 22kW "faster" charger — and for the overwhelming majority of homes it is money wasted. A 7.4kW single-phase charger adds roughly 30 miles of range per hour, fully replenishing any current EV overnight inside a cheap off-peak window. A 22kW unit adds around 90 miles per hour, but it requires a three-phase electricity supply that the vast majority of UK houses simply do not have.

Two further facts kill the case for 22kW at home. First, most electric cars cap their onboard AC charger at 7kW or 11kW, so they physically cannot accept 22kW however fast the wallbox is rated — you would pay for headroom the car never uses. Second, bringing three-phase to a single-phase property means a Distribution Network Operator (DNO) supply upgrade typically costing £3,500–£5,500 (and occasionally far more), with a lead time measured in weeks. The payback on shaving a couple of hours off an overnight charge you are asleep through is effectively never.

The exception is a genuinely heavy-use household — two EVs, high daily mileage, or a home that already has three-phase for other reasons. Here a Zappi is useful because the same unit auto-detects the supply and will deliver up to 22kW on three-phase without buying a different charger. For everyone else, we specify a 7.4kW unit as standard and put the saved budget towards panels or a battery instead.

There is also a solar angle to phase choice. On single-phase, a 7kW charger and a healthy midday surplus are well matched — the car draws power at a rate your array can meaningfully contribute to. Oversizing to 22kW makes the surplus a smaller fraction of demand, so you import more from the grid, not less. Sizing the charger to the roof is part of a properly designed solar panel installation, and it is a conversation we have on every survey across Chippenham and the surrounding towns.

A compliant EV charger installation is more involved than bolting a box to the wall, and the technical detail is where a qualified installer earns their fee. Every domestic charge point must meet BS 7671 Section 722, the wiring-regulation section written specifically for electric-vehicle charging, plus the Smart Charge Points Regulations for the connected features.

The single biggest safety consideration is open-PEN fault protection. Most UK homes use a TN-C-S (PME) earthing arrangement, where a rare break in the supplier's combined neutral-earth conductor could make the car's metal bodywork live. Compliant chargers such as the Zappi and Ohme range have built-in PEN-fault detection that disconnects instantly, which avoids the cost and clutter of a separate earth rod on most jobs. Older or rural TT-earthed properties may still need an earth-rod installation, which we assess on the survey.

Next comes the supply. A 7.4kW charger draws 32A, so on a busy consumer unit we fit load management — a CT clamp that watches total household demand and gently throttles the car if the oven, shower and kettle are all running, keeping you inside your main fuse rating without a supply upgrade. We also handle the DNO notification on your behalf: a 7.4kW unit can be notified after installation, while anything above 7.4kW needs prior approval, which is another practical reason single-phase is simpler. A dedicated RCBO or Type A/B RCD, correct cable sizing and a tidy consumer-unit connection complete the electrical side.

On the day, a straightforward install takes a half day to a day. Our lead engineer's team, working across the SN12 area and out to Melksham and Devizes, will run the cable route, fit the charger, integrate any solar CT for surplus diversion, test and certify, then hand over the app setup. If you are adding a charger to an existing array, it dovetails neatly with a battery storage retrofit so all three systems talk to each other.

A standard 7.4kW smart charger, professionally installed on a modern single-phase supply, typically costs £900–£1,500 depending on the model and cable run. Tethered units and design-led chargers sit at the top of that range; a consumer-unit upgrade, long cable route or earth rod adds to it. We quote the whole job after a survey so there are no surprises — no vague "from" pricing that balloons on the day.

Two levers reduce that figure. The first is 0% VAT. A charger bought and fitted at the same time as a solar or battery system falls under the domestic renewables zero-rate that runs until 31 March 2027, so you save 20% versus a standalone install. Bundling the charger into your solar project is often the single cheapest way to get one fitted.

The second is the EV chargepoint grant. Since the old homeowner grant closed, this scheme is now aimed at renters and flat owner-occupiers, and at households with only on-street parking who install an approved cross-pavement solution. It covers 75% of the buy-and-install cost, and from April 2026 the cap rose from £350 to £500 per socket, with funding confirmed to 31 March 2027. Claims must be submitted by an OZEV-authorised installer against an approved smart charger, so if you live in a flat or rented property in Wiltshire, ask us to check your eligibility before you book — a house with its own driveway will not qualify, and we would rather tell you that up front than imply a discount you cannot claim.

Where a bundle is too much to fund at once, spreading the cost is straightforward. Our solar finance options let you roll the charger into a monthly plan alongside the panels, and the 0% solar finance routes available in 2026 mean the export income and pump-free running costs can offset much of the repayment. For a full breakdown of local pricing, see our guide to solar panel costs in Wiltshire.