Why the obvious way to do this is usually the wrong one
Sending your solar surplus straight into the car feels like the whole point of owning both. In 2026, on a decent export tariff, it is often the more expensive option. The cheapest electric miles in Britain come from selling your sunshine and buying it back at 3am.
Solar panels and an electric car are the strongest pairing in domestic energy. Both are large, both are long-lived, and the combination really does cut a household’s running costs more than either does alone. What almost every guide gets wrong is how the two should be connected, and the mistake costs real money every year.
- Solar diversion is not automatically the cheapest route. Every unit you divert into the car is a unit you no longer export. On a 12p export tariff, diverting costs more than charging overnight at 7p on a smart EV tariff.
- The decision rule is one line. Divert solar into the car only when your export rate is lower than your cheapest import rate. Otherwise export the solar and buy cheaper electricity back at night.
- Your car is usually out when your roof is busiest. Generation peaks between 11am and 3pm on weekdays. A commuter realistically captures around a quarter of their annual charging from solar; a home-based worker gets closer to 70%.
- An EV barely changes the array you should buy. The average UK driver needs about 2,100 kWh a year for the car. Size the system on roof space and budget, then let the tariff capture the value.
- The £500 chargepoint grant excludes most homeowners. Since April 2022 it has been limited to renters, flat owners, landlords and households without off-street parking. It rose from £350 to £500 on 1 April 2026 and runs to 31 March 2027.
How solar charges an electric car
There is no direct wire from the panels to the car. Solar electricity goes through your inverter into the house consumer unit, and the charger draws from the same board as everything else. What differs between setups is the logic deciding when the charger draws and where the electricity comes from.
- Solar diversion. A current transformer clamp on the incoming supply measures surplus. When generation exceeds household demand by enough, the charger starts and modulates its rate to match the surplus, so nothing is drawn from the grid.
- Scheduled off-peak charging. The charger runs in a cheap overnight window on a smart EV tariff. The solar is exported during the day and unrelated electricity is bought back at night.
- Battery buffering. Daytime surplus charges a home battery, which discharges into the car later. This decouples generation from charging entirely, at the cost of round-trip losses and a battery.
- Hybrid modes. Most decent chargers will take all available surplus, then top up from the grid to reach a minimum state of charge by a set time.
All four work. The question this guide answers is which of them is cheapest for you, and the answer depends almost entirely on two numbers on your energy bill rather than on anything about your roof.
- Solar diversion
- Sending surplus generation to a specific load instead of exporting it. Also called solar surplus charging or eco mode.
- Export rate
- What your supplier pays for electricity you send to the grid. Smart Export Guarantee rates run from about 5p to 15p per kWh depending on the deal.
- Opportunity cost
- The export income you give up by using a unit yourself. It is the true cost of self-consumed solar, and it is not zero.
- Smart EV tariff
- A time-of-use tariff with a deep overnight rate for electric vehicle charging, typically 7p to 10p per kWh against a capped day rate around 26p.
- CT clamp
- The sensor around the incoming meter tail that lets a charger see whether the house is importing or exporting in real time.
- Minimum charge rate
- Around 1.4 kW, the floor below which most EVs will not accept a charge. Surplus has to clear this before diversion can start.
- miles per kWh
- Real-world EV efficiency. Most UK cars sit between 3.0 and 4.2, with winter at the lower end.
- DNO notification
- The network operator paperwork an installer files for a 7 kW charger, usually after the fact under the connection rules.
What an electric car actually uses
The average UK driver covers around 7,400 miles a year. At a realistic 3.5 miles per kWh across a British year, including the winter efficiency drop, that is roughly 2,100 kWh of charging.
For scale, a typical home uses 2,700 to 4,000 kWh a year. So an EV adds somewhere between half and three quarters of a household’s existing electricity demand. It is a large load, but it is not the impossible load some guides imply, and it is far smaller than the annual output of a modest array.
| Annual mileage | At 3.0 mi/kWh | At 3.5 mi/kWh | At 4.0 mi/kWh |
|---|---|---|---|
| 5,000 miles | 1,670 kWh | 1,430 kWh | 1,250 kWh |
| 7,400 miles (UK average) | 2,470 kWh | 2,110 kWh | 1,850 kWh |
| 10,000 miles | 3,330 kWh | 2,860 kWh | 2,500 kWh |
| 15,000 miles | 5,000 kWh | 4,290 kWh | 3,750 kWh |
| 20,000 miles | 6,670 kWh | 5,710 kWh | 5,000 kWh |
The diversion trap
Here is the calculation nearly every article on this subject skips.
Solar electricity you use yourself is not free. It has an opportunity cost equal to what you would have been paid for exporting it. On a competitive export tariff paying around 12p per kWh, every unit you push into the car costs you 12p in forgone income.
Meanwhile, a smart EV tariff will sell you electricity overnight at roughly 7p per kWh. Charging from the grid at 3am therefore costs 7p a unit, against 12p a unit for diverting your own solar.
The same logic runs the other way. On a basic 5p Smart Export Guarantee rate with no EV tariff, diverting solar saves you the full difference against a 26p import price, and it is comfortably the best option available. The variable that decides it is not your panels. It is the two rates printed on your energy account.
None of this makes solar pointless for an EV household. The array still earns its keep, and it earns more because an EV household uses and exports more electricity than an average one. The point is narrower: the wire between panel and car is not where the saving comes from. The tariff is.
2,100 kWh of charging a year at the 26.11p capped rate
The same charging shifted into a 7p overnight window
That £401 gap is available to every EV owner with off-street parking, solar or no solar. It dwarfs anything the panels contribute to the car specifically, which is why the tariff decision should come before the hardware decision.
When solar diversion does win
Diversion is the right answer more often than the section above suggests, because plenty of households do not have access to a deep overnight rate. Work through these in order.
- Best when
- SEG rate is 5p or lower
- Needs
- Solar-aware charger
- Car must be
- Home in daylight
- Extra cost
- £0-£150 over a basic charger
- Score
- 3.8 / 5
- Best when
- Export rate is 10p or more
- Needs
- Smart meter, compatible car or charger
- Car must be
- Home overnight only
- Extra cost
- None
- Score
- 4.3 / 5
- Best when
- You want peak-time export too
- Needs
- Battery and active management
- Car must be
- No constraint
- Extra cost
- £4,500-£6,500
- Score
- 4.6 / 5
Buy a charger capable of solar diversion even if you plan to charge overnight. Export rates and EV tariffs move every year, and a charger that can only do one of the two locks you into whichever regime happens to be favourable on the day you bought it. The price difference is usually under £150.
The car is out when the sun is up
Even where diversion is financially right, there is a physical constraint that most sizing guides ignore. UK generation peaks between roughly 11am and 3pm on weekdays. That is precisely when a commuter’s car is in a car park somewhere else.
There is a second constraint underneath it. Most EVs will not accept a charge below about 1.4 kW, so the surplus has to clear that threshold after household demand before diversion can start at all. On a 4 kWp array in April or September, the window where surplus exceeds 1.4 kW may only be three or four hours on a good day, and considerably less on a poor one.
Those figures are the realistic share of annual charging that direct solar diversion can cover, before any battery is involved. If you commute five days a week, direct diversion will handle weekends and holidays and very little else. That is not a failure of the system; it is a reason to stop sizing the array around the car.
A home battery is what closes this gap, not more panels. It stores the midday surplus and releases it to the car in the evening, which turns a 25% solar share into something closer to 60% for a commuter. Whether that is worth £4,500 to £6,500 depends on the battery earning its keep across the whole household, not just the car.
How many panels you actually need
One kilowatt-peak of solar produces roughly 850 kWh a year on a decent south-facing UK roof. An average EV’s 2,100 kWh therefore corresponds to about 2.5 kWp, or six to seven modern panels.
That is the arithmetic answer, and taken literally it is misleading, because the car will not be present to consume most of what those panels make. The better framing is that an EV raises the ceiling on how large an array is worth installing rather than dictating a specific number.
- No EV, no battery. 3.5 to 4.5 kWp. Beyond that, self-consumption drops and you are building an export business.
- EV, charging overnight. 4.5 to 6 kWp. The extra output is exported, which is now worth having because the export income offsets cheap overnight import.
- EV, home in the day. 5 to 7 kWp. Diversion can absorb real volume, so bigger arrays stay useful.
- EV plus battery. 6 to 8 kWp. The battery soaks up surplus that would otherwise export at a low rate.
- High mileage, over 15,000 a year. Size to the roof. Even 8 kWp will not cover 4,500 kWh of charging from daytime generation alone.
The practical rule: fill the usable south, south-east and south-west roof, subject to budget and the inverter. Extra panels cost far less per kilowatt-peak than the first ones did, because scaffolding, labour and certification are fixed.
2026 costs
| Item | Installed cost | Notes |
|---|---|---|
| Solar PV, 4.5 kWp | £5,600-£7,600 | 0% VAT to 31 March 2027 |
| Solar PV, 6 kWp | £6,900-£9,200 | The common EV household size |
| Solar PV, 8 kWp | £8,800-£11,800 | May need a G99 application |
| Basic 7 kW smart charger | £800-£1,000 | Scheduling only, no diversion |
| Solar-aware 7 kW charger | £950-£1,300 | CT clamp included |
| Battery, 10 kWh | £4,500-£6,500 | 0% VAT, standalone or with solar |
| Consumer unit upgrade | £400-£900 | Common on pre-2008 boards |
| Long cable run or trenching | £150-£800 | Detached garage or far parking |
| Public rapid charging, per year | £475-£560 | 2,100 kWh at 22-27p per kWh |
What the full build costs
The entry point is far lower. Solar at 4.5 kWp plus a basic smart charger, with the tariff doing the work, comes in around £6,500 to £8,600 and captures most of the available saving. The battery is the expensive part, and it should be justified on whole-household arbitrage rather than on the car.
Best setups, rated
Scores are out of five and are our editorial judgement, weighted for UK conditions, running cost, how much of the saving is captured, and how well the setup survives a change of tariff.
Solar + battery + smart EV tariff
A 6 kWp array, a 10 kWh battery and a solar-aware charger, running on a deep overnight tariff with an export deal alongside.
The complete answer, and the only setup that is indifferent to when the car happens to be home. The battery charges from midday surplus and from the cheap overnight window, the car charges from whichever is cheaper at the time, and surplus beyond both is exported. It also survives tariff changes, because you are not committed to either diversion or overnight charging being the better deal.
Best for: Commuters / high mileage / households already considering a battery
The best value on this page and the one most households should start with. Export the solar at the best rate you can get, charge the car overnight at around 7p, and skip the battery entirely. It costs roughly £6,500 to £8,600 all in and captures the great majority of the available saving. Add the battery later if the household load justifies it.
Best for: Most EV households / anyone testing the water / commuters without a battery budget
The right answer when your export rate is 5p or lower, or when no smart EV tariff is available to you. Charging becomes close to free in the summer months and the setup is simple, with no battery and no scheduling to manage. Marked down because it only works when the car is home in daylight, and because a low export rate is a problem worth fixing rather than designing around.
Best for: Home-based workers / retired households / second cars / legacy SEG deals
Adequate rather than good. A scheduling-only charger on a fixed off-peak window will capture most of the tariff saving, and all new home chargers sold in the UK must be smart in any case. The limitation is flexibility: no solar diversion, no dynamic response to a tariff that moves its cheap hours, and no easy path to change strategy later.
Best for: Tight budgets / simple fixed-window tariffs / rental properties
A granny cable draws around 2.3 kW, so a full charge takes the best part of a day and a half. It cannot divert solar, cannot respond to a tariff, and puts a sustained high load through a domestic socket that was not designed for it. Acceptable as an occasional backup, poor as a primary method, and it forfeits both the grant and most of the tariff saving.
Best for: Emergencies and visitors, nothing else
Solar-aware chargers compared
All home chargers sold in Great Britain must meet the Electric Vehicles (Smart Charge Points) Regulations 2021, so every unit below has scheduling and connectivity as standard. What separates them is solar diversion and how well they integrate with specific tariffs. Prices are supplied and fitted, before any grant.
| Charger | Typical fitted | Solar diversion | Score |
|---|---|---|---|
| myenergi Zappi | £1,099-£1,299 | Best in class, three modes | 4.5 |
| Ohme Home Pro | £999 | Via tariff, not CT clamp | 4.5 |
| Hypervolt Home 3 Pro | £1,049 | Yes, with sensor | 4.3 |
| Pod Point Solo 3S | £999 | Limited | 4.0 |
| Easee One | £899-£1,050 | Via load balancing | 3.9 |
| Wallbox Pulsar Max | £849-£999 | With power meter add-on | 3.8 |
The two at the top solve different halves of the problem. The Zappi is the strongest true solar diverter, reading surplus through a CT clamp and modulating the charge rate to match it. The Ohme is the strongest tariff integration, taking price signals directly from the supplier and scheduling around them without you touching anything. Which is better depends entirely on which side of the decision rule you fall.
Check that a charger works with more than one supplier before you buy. Some units tie their smart functions to a single energy company’s tariff and fall back to basic timed charging on any other. Given that a charger will outlast several tariff switches, that is a real constraint rather than a technicality.
Grants, VAT and regulations
The chargepoint grant most homeowners cannot claim
The OZEV EV chargepoint grant rose from £350 to £500 per socket for applications made from 1 April 2026, and runs until 31 March 2027. It covers 75% of the cost to buy and install a socket, up to that cap.
Owner-occupiers of standard houses with a driveway have not been eligible since April 2022. The grant is limited to renters, flat owners, residential landlords, and households using an approved cross-pavement solution where there is no off-street parking.
You must own an eligible vehicle, have private off-street parking you are legally entitled to use, and use an OZEV-approved installer. The chargepoint must not be installed before OZEV confirms eligibility, and any landlord or freeholder permission has to be in place before you apply.
VAT
Solar panels and battery storage installed at a UK home carry 0% VAT until 31 March 2027, after which the rate reverts to 5%. That relief does not extend to the EV charger, which is a separate supply at the standard rate. If you are having solar and a charger fitted together, expect the invoice to show different VAT treatment for each, and be wary of any quote that blends them.
Electrical and network rules
- Smart Charge Point Regulations 2021. All new domestic chargers must have scheduling, randomised delay and data connectivity by law.
- Part P. The installation is notifiable electrical work and needs a competent person certificate.
- DNO notification. A 7 kW charger is normally notified to the network operator after installation; larger or multiple installations may need prior approval.
- Earthing. Open-PEN protection is required on most modern chargers, which removes the need for a separate earth rod in the majority of installs.
- Load management. If you have solar, a battery, a charger and an electric shower, ask the installer to model the worst-case simultaneous load against your main fuse.
0% VAT introduced on solar and other energy-saving materials. The homeowner chargepoint grant closed to owner-occupiers of houses.
Up to £3,750 off eligible new EVs, tiered by how sustainably the car and battery are produced, and available on lease and salary sacrifice.
Up from £350 per socket for renters, flat owners, landlords and cross-pavement routes. Funded to 31 March 2027, with a more evidence-based application process.
Solar and battery installations revert to the 5% reduced rate unless the relief is extended.
Government target for zero emission new car sales, rising to 100% by 2035. Expect overnight tariff competition to intensify as volumes grow.
Considerations before you buy
Your export tariff is the biggest lever
Most solar owners are on whatever Smart Export Guarantee rate their supplier defaulted them onto, which can be as low as 4p or 5p. Moving to a competitive fixed export deal at 12p or more can be worth more per year than any hardware decision in this guide, and it is a form you fill in rather than a job you pay for. Do that before you spend anything.
Inverter and battery compatibility
If you plan to add a battery later, specify a hybrid inverter now. Retrofitting AC-coupled storage to a string inverter works but adds a second conversion stage and its associated losses. The cost difference at install is a few hundred pounds; the cost difference later is considerably more.
Where the car parks
Cable runs are the most common source of quote variation. A charger on the house wall next to the parking space is straightforward. A detached garage at the end of a garden may need trenching, armoured cable and a submain, which can add several hundred pounds. Measure the run before you take quotes so they are comparing the same job.
Second cars and mileage
Households with two EVs are a different case. Combined demand of 4,000 to 5,000 kWh means a larger array is clearly justified, and load management between two chargers becomes a design question rather than an afterthought. Say so at the quoting stage.
Find the best export rate and the best smart EV tariff available to you. Those two numbers determine the whole strategy and cost nothing to change.
Annual mileage divided by your car’s real miles per kWh, not the brochure figure. Add household consumption from a recent bill.
Weekdays in daylight, or only overnight? This decides whether solar diversion is worth specifying and whether a battery earns its place.
Specify array size in kWp, inverter type, charger model, cable run length and whether a battery is included now or later. MCS certification for the solar, OZEV approval if you are claiming the grant.
Two to three days for solar, half a day for the charger. Compare the first full month’s import, export and charging figures against the projection you were sold.
Pros and cons
- An EV household uses and exports more, improving solar payback
- Charging costs fall to around 2p per mile on the right tariff
- 0% VAT on solar and battery until March 2027
- Solar diversion makes summer charging close to free on low export rates
- A battery serves the whole house, not just the car
- Home charging avoids public rapid rates five to ten times higher
- Diverting solar can cost more than exporting and buying back
- Commuters capture only about a quarter of charging from direct solar
- Surplus must clear roughly 1.4 kW before diversion starts
- The chargepoint grant excludes most homeowners
- The charger does not qualify for the 0% VAT relief
- Batteries rarely pay back on EV charging alone
Compare your export rate against your cheapest import rate before choosing a strategy.
Buy a charger that can do both diversion and dynamic tariff scheduling.
Specify a hybrid inverter if a battery is even a possibility later.
Measure the cable run to the parking space before requesting quotes.
Assume diverting solar into the car is automatically the cheapest option.
Size the array around the car. Size it around the roof and the budget.
Budget for the £500 chargepoint grant if you own a house with a driveway.
Buy a battery on the strength of EV charging savings alone.
Frequently asked questions
Can solar panels charge an electric car in the UK?
Yes. A 4 kWp array generates around 3,400 kWh a year, comfortably more than the 2,100 kWh an average UK driver needs. The constraint is timing rather than quantity: generation peaks in the middle of a weekday when most cars are away from home, so direct solar charging covers about a quarter of annual mileage for a commuter and around 70% for someone based at home.
How many solar panels do I need to charge an electric car?
On paper, about 2.5 kWp or six to seven panels covers an average driver’s 2,100 kWh a year. In practice, size the array to the roof and your budget instead. An EV raises the ceiling on how large a system is worth fitting, typically to 4.5 to 6 kWp for overnight charging or 5 to 7 kWp if the car is home during the day.
Is it cheaper to charge from solar or from an overnight tariff?
It depends on your export rate. Solar you use yourself costs you the export income you forgo. On a 12p export tariff, diverting solar costs 12p per kWh against roughly 7p from a smart EV tariff overnight, so overnight charging wins. On a 5p export rate with no EV tariff, diversion wins easily. The rule: divert only when your export rate is lower than your cheapest import rate.
Do I need a special EV charger to use solar?
Only if you intend to divert surplus. A solar-diverting charger uses a current transformer clamp to detect export and modulates its charge rate to match, so nothing is drawn from the grid. If you plan to charge overnight on a smart tariff, any compliant smart charger will do. Buying one capable of both costs around £150 more and keeps your options open when tariffs change.
Do I need a battery to charge my EV with solar?
Not to charge the car, but a battery is what lets a commuter use daytime solar at all. It stores midday surplus and releases it in the evening, lifting the solar share of charging from roughly 25% to around 60%. At £4,500 to £6,500, it needs to justify itself across the whole household through off-peak charging and peak avoidance, not on the car alone.
Can I get a grant for a home EV charger?
Only in specific circumstances. The OZEV chargepoint grant pays 75% of the cost up to £500 per socket for applications from 1 April 2026, running to 31 March 2027, but it is restricted to renters, flat owners, residential landlords and households using approved cross-pavement solutions. Owner-occupiers of houses with driveways lost eligibility in April 2022.
How much does it cost per mile to charge an EV on solar?
At 3.5 miles per kWh, roughly 1.4p per mile if your export rate is 5p, or 3.4p per mile if it is 12p, since the export income forgone is the true cost. Charging overnight on a 7p smart tariff comes to about 2.0p per mile. For comparison, a standard tariff is around 7.5p, public rapid charging around 22.6p, and petrol at 50 mpg around 12.3p.
Is VAT charged on an EV charger?
Yes, at the standard rate. The 0% energy-saving materials relief that applies to solar panels and battery storage until 31 March 2027 does not extend to EV chargepoints. If solar and a charger are installed together, the invoice should show the two elements treated differently.
Updated 22 August 2026 with the Ofgem July to September 2026 price cap, current smart EV and export tariff rates, and the OZEV chargepoint grant increase effective 1 April 2026.
Fix the tariff, then buy the hardware
Solar and an electric car belong together, but not for the reason the marketing gives. The value is not in a wire running from the roof to the car. It is in owning a large, flexible load and a generator, and then arbitraging them against a market that pays you 12p for electricity at noon and sells it back at 7p at three in the morning.
Work out those two rates before anything else. If your export rate beats your overnight rate, export the solar and charge the car at night. If it does not, divert. Either way, buy a charger that can do both, because the answer will change.
Size the array to your roof rather than to your mileage, spend the battery money only if the whole household benefits, and treat the £500 chargepoint grant as unavailable unless you rent or live in a flat. Do that and electric miles cost about 2p each.
METHODOLOGY: Costs compiled from UK MCS-certified solar installers and OZEV-approved chargepoint installers, August 2026. Charging demand modelled at 3.5 miles per kWh across a full British year including winter efficiency losses. Generation modelled at 850 kWh per kWp for a south-facing Midlands roof. Cost per mile uses the Ofgem July to September 2026 price cap for standard rates, typical smart EV tariff rates of 7p, and export opportunity cost rather than treating self-consumed solar as free. Solar share percentages modelled against half-hourly generation and typical vehicle presence patterns.
DISCLAIMER: All prices are indicative and exclude consumer unit upgrades, trenching and groundworks. Tariff rates, grant values and eligibility criteria change frequently; confirm the current position with your supplier, GOV.UK and your installer before committing. We do not provide financial or tax advice.
