EV charging from your own solar panels

A charger with a solar or eco mode needs to know what is happening at your meter. A current clamp on the incoming supply, or a link to the solar inverter or battery system, tells it how much electricity is flowing out to the grid. The charger then adjusts its charging current to soak up that surplus rather than importing from the grid.

Cars cannot charge at any power level; below a certain minimum current they stop. On a cloudy day, surplus from a typical home system may not reach that minimum, so most chargers offer a mixed mode that tops up from the grid to keep charging going. On a single-phase supply the charger has less room to adjust than on three-phase. The installer should explain what your panels can realistically deliver to the car in each season.

Solar charging is most useful if the car is parked at home on sunny days: people who work from home, retired households, a second car used mainly at weekends. Each unit that goes into the car instead of being exported replaces a unit you would otherwise buy, so the saving depends on your import price compared with your export rate.

If the car is away in daylight, it can only take solar energy at weekends. Many households in that position gain more from a time-of-use tariff that makes overnight charging cheap, while the panels cover daytime use in the house. The two approaches can be combined: a smart charger can charge overnight on the cheap rate and top up from solar at weekends.

If you already have a home battery or a hot water diverter, they compete with the car for the same surplus. Decide in which order they should take it, and make sure the devices can be set up to respect that order. Some manufacturers offer chargers, inverters and batteries that talk to each other; mixing brands can work, but the installer should confirm how priorities are set.

Vehicle-to-home and vehicle-to-grid systems go one step further and let the car's battery supply the house or export to the grid. They need a bidirectional charger and a compatible car, and they count as generation: the network operator has to be notified or approve the installation under the rules for generators, like a solar system.

A solar-linked charger is still a charge point under the Electric Vehicles (Smart Charge Points) Regulations 2021. It must come with default charging hours outside peak times, which you can accept, remove or change when you first use it, and it must keep charging if the internet connection drops. A solar mode sits alongside these functions, so make sure the default hours do not stop the charger from using daytime surplus.

The installation is a new circuit and notifiable electrical work. The network operator looks at the combined picture of generation, storage and charging at your address, so the installer should include the charger in the same assessment as the panels.

Source: legislation.gov.uk

• charger model and how it measures surplus: clamp, inverter link or energy management system
• whether it offers solar-only, mixed and scheduled modes
• priority between car, home battery and hot water diverter
• compatibility with your inverter, battery and tariff
• network notification for the charger, and for bidirectional systems the generator process
• electrical certificate and Building Regulations notification

Tell us about the panels, any battery, the car and when it is usually at home, then verify your number by text and your email by link. Installers in your area see the details without your identity. Exactly one can buy the request; it then leaves our shop, and the installer pays for it rather than you.

We email you who bought it, with name, address and phone number, before your details are shared. If no installer buys it within 21 days, it is withdrawn. Offrano checks only that the buyer is a registered business, so ask for its competent person scheme registration and, for the solar side, MCS certification.