How much of my solar power can charge my EV?

Typically 25-40% of your solar generation can be diverted to EV charging, depending on when you charge and your household usage. Smart solar diverters can automatically send surplus solar energy to your car. We use 35% as a realistic estimate.

How much solar do I need to charge an EV?

A typical EV doing 10,000 miles/year needs about 2,850 kWh. A 4 kWp solar system in southern England generates about 3,600 kWh/year, of which roughly 1,260 kWh could go to the car. This would cover about 44% of your driving needs for free.

Does solar EV charging work in winter?

Solar generation is much lower in winter (November-February), producing only about 10% of the annual total during these months. Summer months produce the bulk of solar energy, so solar EV charging is most effective from April to September.

What about a battery storage system?

A home battery (e.g. 5-10 kWh) can store excess solar during the day for evening EV charging. This increases the proportion of solar energy you can use but adds significant upfront cost (£3,000-£6,000). The payback calculation should include both the battery and solar panel costs.

How many solar panels do I need to charge my EV?

A typical UK solar panel system (4 kW) generates about 3,400 kWh per year, enough to drive roughly 12,000 miles in an efficient EV. A 10-panel system (3.5 kW) costs £5,000-7,000 and could save £400-600 per year in EV charging costs alone.

CarCalcs

Solar Charging Calculator

Estimate how much free EV charging you can get from solar panels.

Solar System Size

UK Region

Annual Mileage

EV Efficiency

Grid Rate

How We Calculate This

This calculator estimates your annual solar EV charging based on your solar system size and location.

The Calculation

Annual solar generation = System capacity (kWp) x Regional factor (kWh/kWp/year)
Available for EV = Annual solar x 35% (typical diversion rate)
Solar miles = Available kWh x Efficiency (mi/kWh)
Annual saving = Solar kWh used for EV x Grid electricity rate

UK Regional Solar Generation

South England: ~900 kWh/kWp/year
Midlands: ~830 kWh/kWp/year
North England: ~780 kWh/kWp/year
Scotland: ~720 kWh/kWp/year

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Actual figures may vary based on driving conditions, vehicle specifications, and other factors.