Whether it’s commuting to work, going to the shops or visiting relatives, you can’t help but notice the growing number of electric vehicles on our roads. At the end of October 2024, there are around 1.3 million EVs in the UK, representing a five-fold increase since 2000. Roughly one in every five new car registrations is an EV.
These figures will only increase in the future as society makes the shift to greener ways of going about our everyday lives.
To keep their vehicles on the go, more EV owners are looking at solar energy as a sustainable way to charge up their car batteries. And there’s good reason for this. The possibility of charging an EV from solar panels at home can cut down on your costs, as well as reducing your overall carbon emissions – don’t forget, a large percentage of mains electricity is still generated by burning gas. With solar, you know exactly where your electricity is coming from.
It’s not all clear cut though. Solar only works during the day, when most people tend to be away from home. With battery storage, however, solar generated energy can be stored and used to charge an EV at night. We’ll take through the options here, as well as how solar panels can be paired with an EV charger, the benefits and things to keep in mind.
Why use solar panels to charge an electric car?
There are many benefits to charging your electric car with solar energy.
One of the most obvious benefits is the potential for significant cost savings. We’re probably all too aware that electricity costs from the grid have been sky-rocketing recently – despite settling a little bit, they were back up again in October 2024. It’s hard to see this pattern changing any time soon.
But by generating your own electricity, you reduce your dependence on the grid. You’ve got your own supply. This saves on energy bills and brings more stability to your budget.
From an environmental perspective, charging an EV with renewable solar energy is brilliant. It means that no fossil fuels have been burned to generate the electricity and no fossil fuels have been burned when running your vehicle – a two-fold win. It’s safe to say that this drastically reduces your home’s carbon footprint, even if solar can only partly cover your EV charging needs.
An average UK driver who travels about 7,400 miles per year emits 1.6 tonnes of COâ‚‚ annually by using conventional grid electricity. By switching to solar, these emissions are nearly eliminated, making your EV much closer to zero-emission.
How much energy is needed to charge an electric car?
Charging an EV at home using solar energy requires understanding a few key points about energy use.
The energy required to fully charge an EV depends on the size of the battery and your driving patterns. On average, most EVs use about 2,000kWh of energy annually, which works out as around 5.5kWh per day. Of course, this amount varies based on your specific electric vehicle and driving habits.
For example, a smaller EV like the Fiat 500e has a battery capacity of 42.9kWh and offers a range of around 118 miles per full charge. In contrast, a larger EV like a VW ID.Buzz has a 77kWh battery with a 258 mile range. Both the Fiat and VW models will require different charging times and energy input.
It’s also worth noting that factors like driving speed, how often you drive and road type affect battery life. Fast driving, for example, will deplete the battery quicker, meaning you have to charge it more frequently. These factors should be considered when estimating how much energy you’ll need to generate with a solar panel system for regular EV charging.
What size solar panel system will I need to charge an EV?
The size of the solar array you need will depend on:
- The size of your EV battery
- Whether you’re powering other household appliances
Generally speaking, an average 4kW solar PV system made up of between 8 to 14 panels can support home EV charging. Whether this can fully charge your EV each time you plug it in is another question.
As we’ve seen the battery on an ID Buzz has a large capacity of 77kWh. In the UK, we get around 3 peak sunlight hours per day across the year. With a 4kW array, that’s roughly 12kW per day – on a sunny, summer’s day this will be a lot more, but in winter it will be less. You can send some of this solar energy to your battery storage system if you have one (more on that shortly), but if you don’t then it’s highly likely you’ll have to use mains grid electricity to top up your EV charging.
To fully charge an EV with a small 40kWh battery in a single day, a large solar system of 8–10 kW is much more effective. For this size, you’re talking approximately 20 solar panels each with a capacity of 400W.
In short, there are a number of variables that affect the number of solar panels needed, including efficiency and wattage of the panels, the amount of direct sunlight they receive and the availability of battery storage options.
How much do solar panels cost?
The costs for installing a solar system that can help out with your EV charging depends on factors such as the size and quality of the panels, installation complexity and whether or not you opt for battery storage.
For a basic setup, solar panel prices start from £4,500 for a 3kW system and can go up to £12,000 for a larger 10 kW array. The overall installation should include inverters, necessary cabling, panel brackets and labour costs, alongside the panels themselves. Check out our top solar panel manufacturers for more information.
Although it’s not essential, battery storage is highly recommended if you want to charge your EV overnight from your solar generated energy. Adding a battery comes with a cost anywhere from £3,000 to £8,000, depending on the capacity. This price bracket tends to cover batteries with a capacity from 5kW to 16kW. Learn more on solar battery storage prices.
Despite the costs, the potential long-term savings are a significant advantage. This is even more true when paired with energy-saving tariffs like Intelligent Octopus. With Octopus Energy you can charge your EV during off-peak hours at just 7p per kWh – a fraction of the standard unit electricity cost of 25p per kWh.
This kind of plan reduces the cost of charging by up to 70% when compared to typical daytime electricity prices.
Added benefits of solar panels
In almost all scenarios, your solar panels will long outlast your EV. Solar panels have an optimal lifespan of 25-30 years, but even then they should still be functioning. An EV battery is likely to need replacing way before this.
But the major benefit with solar panels is that they will continue generating free energy and will even make you a healthy profit once the initial costs have been paid off. With a typical payback period of 8-12 years, solar panels will go on to save the average household around £20,000 of their lifetime.
Money saving and making use of clean, renewable energy – you can’t ask for much more! Find more benefits of using solar panels here.
Considerations when it comes to solar panel set up for charging
Setting up solar for EV charging should be fairly straightforward but there are a few practical considerations to bear in mind to get the most out of it.
Firstly, not all EV chargers work directly with solar energy. Chargers like Ohme, myenergi Zappi and Wallbox can be configured to use solar energy first, prioritising green power for your EV over other household uses. Whereas other chargers will just take up what’s left after your home has been served first with solar.
Most chargers now come with smart controls which are really handy for increasing efficiency. For example, you can time your EV charging to match peak sunlight hours or store energy in a battery for nighttime charging. If you charge overnight, a smart charger can be set to pull energy from the battery first, making sure you avoid grid power as much as possible.
Do you need battery storage for EV charging?
Battery storage systems can make a big difference if you’re looking to rely mostly on solar for your EV charging. By capturing extra solar energy generated during the day, batteries allow you to access stored power later – for car charging this is usually during the night. Read more on how solar batteries work.
A 5–10 kWh battery is recommended for EV owners who want to minimise grid reliance. With this capacity, you can store enough power to cover a night’s charging needs for most EV models. Larger households or families with multiple EVs will benefit from higher-capacity storage systems. Our guide explains how to calculate battery size for your solar panels.
As we’ve seen with the Octopus Energy tariff, battery systems can help you avoid peak energy rates, which increases your savings even more over time. If you plan to fully power your EV with solar energy, adding a battery is a sound investment. Check out these further benefits of solar battery storage.
Is solar charging for EVs worth it?
We’re big fans of solar energy here, and charging an EV with solar is certainly a worthwhile investment.
Putting a finger on exactly how much you will save each year is difficult to say as there are so many factors at play, such as capacities of your solar and battery, the electricity rates you’re paying across the day, how many miles you drive and more still. Even if solar power only partially covers your EV charging needs, the reduction in grid reliance and energy costs add up.
There’s no doubt that a high initial investment for the panels, EV charger and potentially battery storage is needed, but the combined benefits of lower energy bills, environmental impact and convenience make it an attractive setup for eco-conscious drivers.
