How Cheap Is Driving on Sunshine?
Driving an electric car on sunshine is one of the most satisfying — and financially rewarding — things you can do with solar panels. The average UK driver spends £800-£1,200 per year charging an EV from the grid. With solar panels, that drops to £100-£300. Over 10 years, that’s £5,000-£10,000 saved on fuel alone — on top of the savings solar gives you on household electricity.
But there’s a practical challenge: most people drive to work during the day when solar panels are generating, and plug in at home in the evening when they’re not. This guide explains how to solve that problem, how many panels you actually need, what it all costs, and how to set up a system that genuinely lets you drive on free electricity. For more on how solar panels generate electricity, see our guide on how solar panels work.
Solar EV Charging at a Glance
| Typical solar system size | 5-8kW (for home + EV combined) |
| Panels needed for EV alone | 6-10 panels (2.5-4.5kW) |
| Annual EV electricity demand | 2,500-4,000 kWh (average UK driver) |
| Combined system cost | £7,500-£14,000 (solar + EV charger) |
| Annual fuel savings vs petrol | £1,200-£2,000 |
| Annual fuel savings vs grid charging | £500-£900 |
| Cost per mile (solar charged) | 1-3p |
| Cost per mile (grid charged) | 6-9p |
| Cost per mile (petrol) | 14-20p |
How Much Electricity Does an EV Actually Use?
Before sizing a solar system, you need to know how much electricity your car consumes. This varies significantly by vehicle:
EV Efficiency by Vehicle Type
| Vehicle Type | Efficiency | Annual Electricity (8,000 miles) | Annual Electricity (12,000 miles) |
|---|---|---|---|
| Small EV (e.g., Fiat 500e, MG4) | 3.5-4.0 mi/kWh | 2,000-2,300 kWh | 3,000-3,400 kWh |
| Medium EV (e.g., Tesla Model 3, VW ID.3) | 3.0-3.8 mi/kWh | 2,100-2,700 kWh | 3,200-4,000 kWh |
| Large EV/SUV (e.g., Tesla Model Y, BMW iX3) | 2.5-3.2 mi/kWh | 2,500-3,200 kWh | 3,750-4,800 kWh |
| Performance/Premium (e.g., Mercedes EQS, Porsche Taycan) | 2.0-2.8 mi/kWh | 2,900-4,000 kWh | 4,300-6,000 kWh |
| Plug-in Hybrid (electric miles only) | 3.0-3.5 mi/kWh | 1,000-1,500 kWh | 1,500-2,300 kWh |
Real-world efficiency. Figures include charging losses (typically 10-15%) and seasonal variation (EVs use more energy in cold weather).
The Average UK Driver
The average UK driver covers around 7,400 miles per year. In a typical medium EV, that’s approximately 2,200-2,500 kWh of electricity per year — roughly equivalent to the electricity consumption of an entire average UK household.
How Many Solar Panels Do You Need?
Understanding your panel requirements is crucial for proper system sizing. For a comprehensive guide on calculating this, see our article on how many solar panels you need.
For EV Charging Only
| Annual Mileage | Annual kWh Needed | Solar Capacity | Panels (420W) |
|---|---|---|---|
| 5,000 miles | 1,500-1,800 kWh | 2-2.5kW | 5-6 panels |
| 8,000 miles | 2,200-2,800 kWh | 3-3.5kW | 7-8 panels |
| 12,000 miles | 3,400-4,200 kWh | 4-5kW | 10-12 panels |
| 15,000 miles | 4,200-5,300 kWh | 5-6.5kW | 12-15 panels |
Based on 850-900 kWh generation per kW of solar in the UK.
For Home + EV Combined (Recommended)
Just like with air conditioning, don’t size your solar system for EV alone. Size it for your total household electricity plus EV charging. This maximises the value of every panel.
| Household Size | Home Electricity | EV Electricity | Total | Solar System | Panels |
|---|---|---|---|---|---|
| 1-2 bed, low mileage | 2,000-2,500 kWh | 1,500-2,000 kWh | 3,500-4,500 kWh | 4-5kW | 10-12 |
| 3 bed, average mileage | 2,700-3,100 kWh | 2,200-2,800 kWh | 5,000-6,000 kWh | 6-7kW | 14-17 |
| 4+ bed, high mileage | 3,500-4,500 kWh | 3,500-4,500 kWh | 7,000-9,000 kWh | 8-10kW | 19-24 |
| Any home, two EVs | 2,700-4,000 kWh | 4,500-6,000 kWh | 7,200-10,000 kWh | 8-12kW | 19-28 |
For most households with one EV, a 5-7kW solar system is the sweet spot — enough to cover a meaningful portion of both home and car electricity. Common system sizes include 5kW and 6kW systems.
Compare system sizes and costs in our guide to solar panel systems for UK homes.
How Much Does Solar EV Charging Cost?
Combined System Costs
| Component | Budget | Mid-Range | Premium |
|---|---|---|---|
| Solar PV (5kW) | £5,500-£6,500 | £6,500-£7,500 | £7,500-£9,000 |
| EV charger (7kW) | £500-£700 | £700-£1,000 | £1,000-£1,500 |
| EV charger installation | £300-£500 | £300-£500 | £300-£500 |
| Battery (optional, 5kWh) | — | £2,500-£3,500 | £3,500-£5,000 |
| Total (no battery) | £6,300-£7,700 | £7,500-£9,000 | £8,800-£11,000 |
| Total (with battery) | — | £10,000-£12,500 | £12,300-£16,000 |
For detailed solar panel pricing, see our guide to solar panel costs in the UK.
EV Charger Options
| Charger | Power | Cost (supply + install) | Solar Features |
|---|---|---|---|
| Ohme Home Pro | 7.4kW | £800-£1,100 | Smart scheduling, cheap tariff integration |
| Zappi V2 | 7.4kW | £900-£1,300 | Best solar integration — eco and eco+ modes |
| Wallbox Pulsar Plus | 7.4kW | £700-£1,000 | Power boost, solar compatible via app |
| Easee One | 7.4kW | £800-£1,100 | Dynamic load balancing, clean design |
| Tesla Wall Connector | 7.4kW | £600-£900 | Tesla integration, basic solar compatibility |
| Hypervolt Home 3 | 7.4kW | £750-£1,050 | App scheduling, energy monitoring |
The Zappi: Best Charger for Solar
The myenergi Zappi deserves special mention because it’s specifically designed for solar-powered EV charging. It has three charging modes:
Fast Mode
Charges at full speed from whatever source is available — solar, grid, or both. Use this when you need the car charged quickly regardless of source.
Eco Mode
Uses all available solar surplus, topped up with grid electricity to maintain minimum charge speed (1.4kW). Your car charges steadily throughout the day, prioritising solar but not stopping if clouds roll in.
Eco+ Mode
Charges only from surplus solar — if solar drops below the minimum threshold, charging pauses until it returns. This is the purest “drive on sunshine” mode. Your car might charge in bursts throughout the day as clouds come and go, but every kWh comes from your panels.
The Zappi communicates with a CT clamp on your supply to measure real-time solar surplus. No internet connection or complex setup needed — it just works.
The Timing Problem (and How to Solve It)
The fundamental challenge of solar EV charging is timing:
- Solar generates: 8am-6pm (peak 10am-3pm)
- Car at home: Often only evenings and overnight
- Car plugged in: Typically 6pm-8am
If you commute to work during the day, your car isn’t home when the sun is shining. There are several solutions:
Solution 1: Charge When You’re Home (Simplest)
If you work from home, work part-time, are retired, or have flexible hours, this is straightforward. Plug in during the day and let solar charge your car directly.
- Solar utilisation: 60-90% of EV charging from solar
- Cost: No extra equipment needed beyond solar + charger
- Best for: Home workers, retirees, part-time workers
Solution 2: Battery Storage (Most Effective)
A home battery stores solar energy generated during the day and releases it to charge your car in the evening.
- How it works: Solar charges battery during day → you plug in car at 6pm → battery powers charger
- Solar utilisation: 50-70% of EV charging from stored solar
- Battery size needed: 5-10kWh covers a typical daily commute (20-40 miles)
- Cost: £2,500-£6,000 for battery
- Best for: Commuters who drive daily and want maximum solar use
Solution 3: Cheap Overnight Tariff (Most Practical)
If you don’t have a battery, charge overnight on a cheap EV tariff instead:
- Octopus Intelligent Go: 7.5p/kWh overnight (vs 28-35p daytime)
- OVO Charge Anytime: Similar off-peak rates for EV owners
- How it works: Solar powers your home during the day (saving 28-35p/kWh), car charges overnight at 7.5p/kWh
- Effective cost: You’re not charging directly from solar, but your solar savings during the day more than offset the cheap overnight charging
- Solar utilisation: Indirect — solar saves money during day, car charges cheaply at night
- Best for: Daily commuters without battery storage
Solution 4: Weekend and Holiday Charging
Even commuters have their car at home on weekends and during holidays — that’s roughly 120-150 days per year. On these days, direct solar charging is easy.
- Solar utilisation: 30-40% of annual EV charging from solar
- No extra equipment needed
- Best for: Everyone — this is free benefit on top of other solutions
Cost Per Mile: The Full Picture
This is where solar EV charging gets exciting. Here’s what it costs to drive a mile using different energy sources:
| Energy Source | Cost per kWh / litre | Cost per Mile | Annual Cost (8,000 miles) |
|---|---|---|---|
| Petrol car (40mpg) | £1.40/litre | 16-20p | £1,280-£1,600 |
| Diesel car (45mpg) | £1.45/litre | 14-18p | £1,120-£1,440 |
| EV — public rapid charger | 60-80p/kWh | 17-25p | £1,360-£2,000 |
| EV — home grid (standard tariff) | 28-35p/kWh | 8-11p | £640-£880 |
| EV — cheap overnight tariff | 7-8p/kWh | 2-3p | £160-£240 |
| EV — solar panels (direct) | 0p/kWh | 1-2p | £80-£160 |
Solar cost per mile accounts for system degradation and opportunity cost of export (you could sell that electricity at 4-15p/kWh instead). True marginal cost of solar-charged miles is effectively zero.
Summary
| Aspect | Details |
|---|---|
| Solar system size | 5-7kW for one EV + home, 8-12kW for two EVs |
| Panels for EV alone | 6-10 panels (2.5-4.5kW) |
| Best EV charger for solar | Zappi V2 (eco and eco+ modes) |
| Combined cost (solar + charger) | £7,500-£14,000 |
| Cost per mile (solar) | 1-2p (vs 16-20p petrol) |
| Annual savings vs petrol | £1,100-£1,500 |
| Payback period | 5-8 years (solar + charger) |
| Best for daytime charging | Home workers, retirees, flexible workers |
| Best for commuters | Battery storage or cheap overnight tariff |
| Future technology | V2H — car becomes your home battery |
Solar panels and electric cars are two of the smartest investments a UK household can make — and together, they’re even better. Driving on sunshine costs 1-2p per mile compared to 16-20p for petrol, and a combined solar + EV charger system pays for itself in 5-8 years while delivering 20+ years of dramatically reduced motoring costs.
The ideal setup for most households is a 5-7kW solar system, a Zappi or similar solar-aware EV charger, and — if budget allows — a 5-10kWh home battery to bridge the gap between daytime generation and evening charging. Even without a battery, solar makes a substantial dent in your EV running costs, especially when combined with a cheap overnight tariff for winter top-ups.
For solar system sizing, see our guide to solar panel systems. For costs, see our solar panel cost guide.
