Solar Panels and EV Charging: What You Need to Know

Combining solar panels and EV charging under the same roof can significantly reduce your fuel costs. If your solar system generates more than your home is using, that surplus can charge your car at little or no extra cost through a solar diverter - a device that redirects excess solar electricity to your EV charger. Savings depend on how much you drive, when you charge, and the size of your solar system.

How much electricity does EV charging use?

Topping up after a typical daily commute adds around 10-20 kWh to your consumption. kWh - kilowatt hours - is the unit used on your electricity bill; it is also the unit your EV charger draws. Charging from near-empty adds 60-80 kWh for most mainstream electric cars.

For context, a 4 kWp solar panel system - where kWp stands for kilowatt peak, the measure of maximum output under ideal conditions - generates around 3,400 kWh per year in the East of England, based on MCS - Microgeneration Certification Scheme, the quality standard for solar installers - performance estimates. That is broadly equivalent to the annual charging requirement for a driver covering around 8,000 miles per year.

The timing mismatch is the key challenge. Solar panels generate electricity during daylight hours. Most people charge their cars overnight. Without a way to bridge this gap, overnight charging draws from the grid rather than from your panels, at your standard electricity tariff.

Solar diverters: making the most of surplus solar

A solar diverter - a device that monitors your household’s real-time generation and consumption, and redirects any surplus solar electricity to your EV charger rather than exporting it - is the most cost-effective way to combine solar panels and EV charging.

Without a diverter, surplus solar is exported to the grid and earns a few pence per kWh under the SEG - Smart Export Guarantee, the scheme that pays you for unused solar electricity sent back to the grid. You can read more about how the Smart Export Guarantee pays you. Charging your car with that same electricity is typically worth significantly more per kWh than any export rate, because you are avoiding grid electricity you would otherwise buy.

Solar diverters cost around £250-£600 fitted as of 2026, and are compatible with most standard 7.2 kW home EV charger units. As a guide, diverting surplus solar could save a driver covering 8,000 miles per year an estimated £200-£400 annually, based on a 25p/kWh import tariff and a 5p/kWh SEG export rate. Figures vary depending on system size, mileage, and your specific tariff.

Should you add a battery as well?

A diverter captures surplus solar only while your panels are generating, which limits how much overnight charging it supports. A home battery stores daytime surplus for release later in the evening, making it possible to charge your EV from solar electricity even after dark. Whether the extra investment is worthwhile depends on your driving patterns and how much surplus your system generates. Read more about pairing solar with battery storage to understand when it adds genuine value.

A capable home battery (10 kWh or more) typically costs £5,000-£10,000 fitted as of 2026. That is a substantial addition to the cost of a solar system - see what a solar panel system typically costs before deciding whether to include battery storage from the outset or add it as a second phase.

Frequently Asked Questions

Do I need a special solar system to charge an EV from solar?

No. You can add a solar diverter to most existing solar panel installations without replacing the panels or inverter. You will need a compatible home EV charger; most standard 7.2 kW tethered or untethered units work with diverters. If you are planning a new installation with EV charging as a priority, tell your installer at the outset so the diverter can be incorporated into the original design.

How much could I save by charging my EV from solar panels?

Savings depend on your mileage, electricity tariff, and how much surplus your solar system generates. As a guide, a driver covering 8,000 miles per year with a 4 kWp system could save an estimated £200-£400 annually by self-consuming surplus solar rather than paying grid rates to charge overnight, based on a 25p/kWh tariff and 5p/kWh export rate as of 2026. Figures vary depending on those factors.

Will my Smart Export Guarantee payments fall if I charge an EV?

Yes. If you are diverting surplus solar to your EV charger rather than exporting it, you will send less electricity to the grid and receive lower SEG payments. Whether this is worthwhile depends on the gap between your import tariff and your export rate. At typical current rates - around 25p/kWh for import versus 3p-15p/kWh for export - self-consuming in your EV is usually the better financial outcome.

Does EV charging mean I need a larger solar system?

Not necessarily, but a larger system generates more surplus for the diverter to capture during the day. A 4 kWp system is a common starting point for a household with an EV. Adding one or two extra panels to reach 5-6 kWp is worth discussing with your installer if EV charging is a priority, as the marginal cost of additional panels is lower once scaffolding and labour are already included in the quote.