How to Charge Your Electric Car Using Solar Panels

How Does Solar EV Charging Work?

When your solar panels generate more electricity than your home is using, that surplus is normally exported to the grid — earning up to 25p per kWh via the Smart Export Guarantee (average rates are lower at ~13p/kWh). A smart EV charger like the Zappi diverts that surplus into your car instead, meaning you use electricity you've generated yourself rather than exporting it cheaply and then buying it back expensively.

The charger monitors your solar generation and household consumption in real time, automatically adjusting the charge rate to use available surplus. On a sunny day, your car charges on free electricity.

Which EV Charger Works with Solar Panels?

The myenergi Zappi is the most popular solar-compatible EV charger in the UK, and the one we install most frequently. It operates in three modes:

• Eco mode — Charges at a minimum rate from the grid, topping up with any available solar surplus.
• Eco+ mode — Only charges when solar surplus is available. The car will wait until enough solar is being generated.
• Fast mode — Standard 7.4 kW charging regardless of solar generation.

For a full walkthrough of our EV charger installation service, including other smart charger options, visit the main EV charger page.

How Much Can You Save Charging on Solar?

An electric car driving 10,000 miles per year needs roughly 2,000–2,500 kWh of electricity. At 24.67p/kWh from the grid, that's £493–£617 per year. If 60% of charging comes from free solar electricity, you save approximately £300–£370 per year on fuel alone — in addition to the household savings from the solar system itself.

The exact percentage of solar charging depends on how often the car is plugged in during daylight hours and your solar array size. A typical 4–5 kW system in Cornwall (which has the UK's best solar resource) will comfortably support one EV charged during daytime hours.

Do I Need a Battery as Well?

A battery is not required, but it extends the benefits. Without a battery, you can only charge your car on solar during the hours when you're generating surplus. With a battery, you can store daytime solar and use it in the evening — either to charge the car after work or to power the house overnight.

The most common setup we install for EV owners is a 4–5 kW solar system, a 5–10 kWh battery, and a Zappi charger. This combination provides good daytime and evening solar use for both the house and the car.

Installation Process

Installing a Zappi charger alongside existing solar panels is a one-day job. We fit a CT clamp (current transformer) to your electricity supply to measure solar generation and household consumption, then connect the Zappi to your fuse board and mount it on an external wall. The myenergi app lets you monitor charging, set schedules, and control the mode remotely.

If you don't yet have solar panels, we can install solar and the EV charger together — often the most cost-efficient approach. See our solar panel installation page for details.

Is It Worth It?

If you own or are planning to buy an electric car, combining it with solar panels and a smart charger is one of the best financial decisions available to homeowners. The savings compound — solar saves on household electricity, the Zappi channels surplus into the car, and together they reduce two major household costs simultaneously.

We install EV chargers and solar panels across Truro, Newquay, Bodmin, St Austell, and all of Cornwall. Book a free survey to explore your options.