Using solar to charge your electric car sounds like the perfect solution. And yes, you can absolutely use solar panels to charge your EV.
In fact, if you already have solar panels or are thinking about installing them alongside an EV charger, combining the two can help you make better use of the electricity your home generates.
However, there is a caveat. Solar EV charging isn’t quite as simple as plugging your car directly into the panels and expecting a full battery every day.
The key is designing your solar, battery and EV charging setup so it uses as much of your own generation as possible, while still giving you flexibility when the sun stops shining.
How does solar EV charging work?
Your solar panels generate electricity during daylight hours. That electricity first passes through your solar inverter, which converts it into electricity your home can use.
From there, the power can be used in several ways. It may run appliances in your home, charge a solar battery, power your electric car or be exported to the grid.
For example, imagine your solar panels are generating 4kW of electricity on a sunny afternoon. Your home is using 1.5kW for appliances, lighting and other demand. That leaves around 2.5 kW available.
A suitable EV charger can use that spare electricity to charge your car rather than exporting it to the grid.
Do I need a special EV charger?
Technically, any properly installed home EV charger will work. However, it won’t work optimally. A standard charger will usually charge your car at the selected rate, even if that means drawing additional electricity from the grid.
What you ideally need is a solar-compatible smart charger. These chargers monitor the electricity flowing into and out of your property and adjust the charging rate to match your available solar surplus. In other words, when your panels are generating more electricity than your home needs, the charger can direct that spare power to your car.
This is often called solar surplus charging, solar matching, eco charging or green charging.
Some chargers can run in different modes, such as only charging the car when there’s enough spare solar generation available, or using as much solar as possible but drawing a small amount from the grid if necessary to keep charging.
That gives you a choice between prioritising self-generated electricity and making sure the car is ready when you need it.
Will solar panels charge my car at full speed?
Not usually. Solar panels don’t typically produce as much power as you can get from the grid, which means they don’t charge as quickly.
Many home EV charge points can charge at up to around 7kW. However, a typical domestic solar system may generate less than this for much of the day, especially once your household electricity use is taken into account. In ideal summer conditions, with no shading or cloud cover and very little electricity demand in the home, your panels may occasionally get close to supplying that full charging rate. In reality, though, solar output changes throughout the day, so this is unlikely to be sustained.
That does not, however, mean solar charging isn’t worthwhile. On a bright day, your car might receive a useful top-up while it’s parked at home. Across a week, month or year, those top-ups can make a meaningful difference to how much grid electricity you need to buy.
Can I charge my EV with solar at night?
Not directly. Your solar panels don’t generate electricity after dark.
With that said, you can still charge your car overnight using grid electricity, and this is often the most practical option if your vehicle is away from home during the day. Many EV owners use an off-peak electricity tariff to charge overnight at a lower rate.
Another option is battery storage. Instead of exporting spare solar electricity during the day, you can store some of it in a home battery and use it later in the evening.
However, a battery is not essential for solar EV charging. It’s most useful when you want to use more of your own solar generation after the sun has gone down, or when your car is usually at home in the evening rather than during the day.
In truth, most household batteries don’t store more than 30kWh, while your EV battery is likely to be significantly larger. A home battery can therefore help you use some stored solar energy to top up your car in the evening, but it’s unlikely to hold enough electricity to charge it from 0% to 100%.
What happens in winter or on cloudy days?
Your solar panels will still generate electricity in winter, but generally much less than they produce during summer.
A solar-compatible EV charger can continue to use any surplus electricity that is available. However, there will be more occasions when you need to use electricity from the grid, particularly during darker months or when several appliances are running in the house.
This is why it’s best to view solar EV charging as one part of a flexible home energy system rather than expecting your panels to supply every mile you drive throughout the year.
Is charging from solar always the cheapest option?
Not always. Using your own solar electricity means you avoid buying that unit of power from your supplier. That usually works out as the cheapest option. But you may also receive payment for exporting unused solar electricity to the grid.
At the same time, some EV tariffs offer cheap overnight charging rates. Depending on your electricity import rate, export rate and driving habits, it can sometimes make sense to export solar electricity during the day and charge your car overnight.
A smart system gives you the flexibility to choose the approach that works best for your household.
Planning a solar and EV charging system
The best results come from planning your solar panels, EV charger, battery storage and household electricity use together. Where possible, we recommend choosing compatible battery storage, EV charging and solar equipment from the same manufacturer, such as Sigenergy. This maximises compatibility and gives you the most freedom to decide how to use your electricity.
We’ll look at factors such as your typical driving mileage, when your car is parked at home, the size and output of your solar array, your electricity tariff, your consumer unit and the best location for the charge point. With the right setup, solar panels can help reduce the cost of charging your electric car while giving you more control over where your electricity comes from.
Contact Electrical Innovations to discuss a solar, battery storage, or EV charging installation for your home. Our number is 01332 498130. We look forward to your call.
