Can I Charge My Electric Car From My Solar Panels?

Yes. A solar-aware home charger can send the electricity your panels are producing, and the house isn’t using, into the car instead of exporting it to the grid. It works best when the car is plugged in at home during the day, in the brighter months, on a system that regularly has power to spare.

What it can’t do is charge a car from solar alone on a grey winter afternoon. This guide explains why, what the charger settings mean, and how to stop a home battery emptying itself into the car.

Key points

• A solar-aware charger measures what your home is exporting and diverts that surplus to the car.

• Cars won’t charge below a minimum current of 6 amps, roughly 1.4 kW on a single-phase supply. Below that, a solar-only setting simply waits.

• Most chargers offer a mixed setting that tops up from the grid so the car keeps charging when the sun dips.

• In London, winter surplus is small. Expect solar charging mainly from spring to autumn, with cheap overnight charging the rest of the time.

• Without the right set-up, a home battery can discharge into the car. The charger, battery and sensors need configuring together.

How solar charging works

Your panels produce power, the house uses what it needs, and anything left over normally goes to the grid as export. A solar-aware charger has a sensor, usually a clamp on the main incoming cable or a link to your inverter, that measures that export. When it sees a surplus, it sends it to the car instead.

As clouds pass and the kettle goes on, the surplus changes minute by minute, and the charger adjusts its charging rate to follow it. That is the difference between a solar-aware charger and an ordinary smart charger on a timer: the timer only knows the time of day, while the solar charger is watching your generation.

The minimum a car will charge at

Under the charging standard most home chargers and cars follow (IEC 61851-1), a car needs at least 6 amps per phase before it will start charging. On a typical single-phase home supply that is about 1.4 kW. On a three-phase supply the charger needs 6 amps on every phase, about 4.2 kW in total, unless it can switch down to single-phase when the sun is weaker.

So in a solar-only setting, nothing happens until your spare generation passes that threshold. A morning when the house is using most of the output, or a dull day, may never get there.

The settings you’ll usually see

The names vary between manufacturers, but most solar-aware chargers offer three kinds of setting:

• Solar only: charges purely from surplus, and pauses whenever there isn’t enough.

• Solar with grid top-up: uses whatever surplus there is and draws the rest from the grid, so charging carries on at the minimum rate.

• Fast or scheduled: charges at full speed from any source, either now or at a set time such as a cheap overnight tariff window.

Many owners use solar only during the day and a scheduled charge overnight, so the car is always ready in the morning.

What changes through the year

In London, a solar system produces far more in June than in December. Long summer days with the house quiet can give hours of surplus. In winter, generation is lower and the days are shorter, the house uses more, and the surplus may never reach the car’s minimum. For most homes, solar charging is a spring-to-autumn bonus rather than a year-round supply, and an overnight time-of-use tariff covers the rest. Our guide to Octopus Flux explains how one time-of-use tariff works.

The biggest factor of all is when the car is at home. A car that is out all day misses the solar window entirely, however large the system.

Smart charger rules and solar

Home chargers sold in Great Britain must meet the Electric Vehicles (Smart Charge Points) Regulations 2021. Among other things, they come with default charging hours that avoid the weekday peaks of 8am to 11am and 4pm to 10pm, and a random delay of up to 10 minutes at the start of each charge to spread demand on the network. You can change the default hours or override them.

Midday solar charging falls outside those peak windows, so the default settings and solar charging don’t clash. If your charger seems to wait a few minutes before it starts, that may be the random delay.

Adding a home battery to the picture

A charger can’t tell whether the power it draws comes from the panels, the battery or the grid. Without the right set-up, a home battery will happily discharge into the car in the evening. A car battery is many times larger than a home battery, so it can empty the home battery quickly and leave the house on grid power for the night.

There are two sensible ways to set it up, and the right one depends on your tariff and how you use the car:

• Keep the home battery for the house: the sensors and settings are arranged so the battery ignores the car. This is the usual choice.

• Let the battery help at set times: for example on a time-of-use tariff, where using stored charge for driving can make more sense than exporting it.

Either way, the charger, inverter, battery and sensors need setting up together. Our guide to why a battery won’t discharge covers the settings that can stop a battery powering the car on purpose.

Will my system cope?

A home charger is one of the biggest loads a house can have. Before fitting one, an installer should check the supply capacity and main fuse, the earthing arrangement, and what else is drawing power, such as a heat pump, an electric shower or a battery charging from the grid. Many chargers have load management that slows charging when the house needs the power.

Many London homes are on a PME earthing system, which needs extra protection for a charger used outdoors. The installer confirms this at the survey. You don’t need to know the detail, but it is one reason a charger isn’t a plug-in job. Our EV charger installation page explains how we survey and fit chargers for solar and battery homes.

Do I need more panels?

Not necessarily. A system that regularly exports plenty in summer already has surplus to send to the car. If you want more solar charging, adding panels can help where roof space allows, though it can affect your connection with the network operator and, on older systems, your Feed-in Tariff. Our guide to adding more panels to an existing system explains the rules.

Frequently asked questions

Can I charge my car only from solar?

On a bright day with the car at home, often yes. On dull days and in winter, a solar-only setting may never reach the car’s minimum charging current, so most owners keep an overnight schedule as a back-up.

Does my charger need to be a particular brand?

It needs a solar mode and a way to measure your export, usually a clamp on the main cable or a link to your inverter. Several manufacturers make chargers that do this, and we match the charger to your system at the survey.

Will my home battery drain into my car?

It can, unless the system is set up to prevent it. Tell your installer you have, or plan to have, a battery, so the sensors and settings are arranged correctly from the start.

Is there a grant for a home charger?

Government chargepoint grants currently cover groups such as flat owners and renters with private parking, but not owner-occupiers of houses. The scheme is due to run until 31 March 2027, so check the current rules on GOV.UK before relying on it.

Can you add a charger to a solar system someone else installed?

Yes. We check the existing inverter, battery and monitoring first, so the charger works with them rather than against them.

Request an EV charger survey. We’ll check your supply, your solar output and any battery, and set the charger up to work with all three.