How many solar panels do you need to charge an electric car?

By the SmartSolarSizer team · Published 20 October 2026

Start with your miles: how many kWh an EV uses a day

The battery size on the spec sheet tells you surprisingly little. What your panels have to replace is the energy you used today, and that depends on how far you drove. The average US driver covers 13,476 miles a year, or about 36.9 miles a day (FHWA). Multiply that by the car's efficiency rating:

The kWh per 100 miles figure is the EPA rating listed on fueleconomy.gov, and it is measured at the wall. EPA's tests assume Level 2 charging and count the losses in the charging cable and the car's on-board charger, measuring energy "from the vehicle to the outlet in the wall" (EPA). Those losses are real, about 16% between the wall and the battery according to the US Department of Energy (DOE), but they're already inside the rating.

A common mistake in EV solar estimates is taking the EPA number and adding another 10–15% for charging losses, which counts them twice and oversizes the array. The one exception is a standard 120 V socket. EPA's figures assume Level 2, so if you only ever charge from a wall socket, leave yourself a small margin.

How many solar panels for a Tesla Model 3, Model Y and other EVs

Here are seven popular EVs at 36.9 miles a day, using their 2025 EPA ratings (fueleconomy.gov) and 430 W panels on an average day:

Take the Model 3 Long Range: 36.9 × 25 ÷ 100 = 9.2 kWh. One 430 W panel in New York makes 1.66 kWh on an average day, so 6 panels (2.58 kW) cover it with a little to spare. The Model Y uses 2 kWh more per 100 miles, which is 0.7 kWh a day and just enough to need a seventh panel in New York. So the efficiency rating, not the badge, sets the panel count. An F-150 Lightning doing the same miles uses 18.1 kWh, which takes 11 panels in New York.

Using kilometres? Divide kWh per 100 miles by 1.609. The Model 3's 25 kWh/100 mi works out at about 15.5 kWh/100 km.

Panels for a Model 3 in 14 cities, including the darkest month

Same car, same 36.9 miles a day. The last column is what it would take to cover the car from solar alone in each location's worst month:

The two columns pull apart a long way at high latitudes. Berlin needs 8 panels on an average day and 23 in December. On a grid-tied home you size for the average and let the summer surplus cover winter; nobody should build the December column onto a roof unless they're truly off-grid.

How long would it take to charge an EV with a solar panel?

With one panel, a long time. A single 430 W panel in New York makes about 1.66 kWh on an average day, which is roughly 6.6 miles of driving in a Model 3. Replacing a 36.9-mile day would take that panel about 5.6 days of sunshine. The 6-panel array does it in one.

The time you see on the car's screen is a different thing: it depends on the charger, not on the panels. A Level 1 connection (a standard 120 V outlet, about 1.9 kW) adds around 5 miles of range per hour, and a residential Level 2 charger at up to 7.2 kW adds around 25 (AFDC). So the average day's 36.9 miles takes about 1.5 hours on Level 2 or 7.4 hours on Level 1, whatever size of array is on the roof.

Can solar panels charge an EV directly?

Not in the way most people picture it. A 7.2 kW Level 2 charger running flat out draws as much as 17 panels' worth of rated output, while the array that covers an average day's driving in New York is 2.6 kW. Panels sized for your miles will never keep up with the charger minute by minute, and they don't need to. There are two sensible setups.

The first, and by far the simplest, is a grid-tied system with net metering. The panels export during the day, the car charges overnight, and over the month the solar covers the car's energy. The grid is just the go-between. The second is a solar-matched charger, which follows your surplus and charges the car only with power you would otherwise export. It pays off when the car is parked at home in daylight and your utility pays little for exported power.

What we'd skip is charging the car from a home battery. You store the same energy twice and lose some each time, and a single day's driving can empty a battery bought to run the house during outages.

Portable solar panels for EV charging: the honest maths

Fold-out panels on the roof of a parked car look appealing, but the numbers are small. Give a 100 W portable panel the best case, performing like a fixed roof panel at the ideal angle, and in New York it makes about 0.39 kWh on an average day. That's about 1.5 miles in a Model 3. Laid flat or propped against a windscreen it will do worse.

There's a second catch. Even a Level 1 connection draws about 1.9 kW, many times more than a portable panel produces, so in practice the panel trickles energy into a power station and the power station does the charging. Treat it as a way to creep to the next charger in an emergency, not as a fuel source.

Charging an electric car with solar panels in the UK

Newer battery-electric cars in the UK averaged 10,054 miles in 2024, about 27.5 miles a day (RAC Foundation). In a Model 3 that's 6.9 kWh a day, or 6 panels on an average London day.

A typical UK home system is about 4.5 kWp, roughly 12 panels (Energy Saving Trust). In London that makes about 12.6 kWh on an average day, so the car on its own would use around 55% of it. In December the same system makes about 5.6 kWh a day, less than the car needs. Month by month, that system makes more than the car's 6.9 kWh a day in every month except January and December, before the house takes its share. So adding an EV to an existing UK system works well from spring to autumn, and in midwinter the car leans on the grid.

Winter: the car needs more, the panels make less

Cold weather pushes the two sides of the sum in opposite directions. An EV uses more energy per mile when it has to heat the cabin and battery, just as solar output falls. In New York, 1 kW of panels makes 2.81 kWh a day in December against 3.85 on an average day. On a grid-tied home this is fine, because you size for the yearly total. If you're planning an off-grid setup around an EV, the worst-month column above is the honest number, and in northern Europe it is large.

Is solar worth it if you have an EV?

An EV doesn't change what a panel produces. It changes how much of that output you can use well. An average US driver in a Model 3 adds about 3,369 kWh a year to the home's demand, so a solar system has a bigger, steady load to offset.

Whether that makes solar pay comes down to three things. First, how your utility treats exported power: with full net metering it hardly matters when the car charges, but where export earns much less than grid power costs, charging in daylight or with a solar-matched charger is worth real money. Second, whether the car is at home during the day. Third, you need roof space for the car's 6 or more panels on top of what the house needs. For most people the right move is to size for the house and the car's yearly kWh together, then check the payback with your own tariff in the payback guide or the full calculator.

Common questions

Sources

Solar output for every location comes from the European Commission's PVGIS 5.3 (1 kW system, panels at the best fixed angle facing the equator, 14% system losses), retrieved 20 October 2026. Panel counts assume 430 W panels, the most common size in 2025 home solar quotes (EnergySage).

• fueleconomy.gov: 2025 all-electric vehicles (kWh per 100 miles)
• EPA: fuel economy and EV range testing (ratings include charging losses)
• FHWA: average annual miles per driver
• RAC Foundation: average mileage of newer cars and EVs, 2024
• Alternative Fuels Data Center: charging stations and power levels
• US DOE Fact of the Week #1045: where energy goes in an EV
• Energy Saving Trust: solar panels (typical UK system size)

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