Is it worth getting solar panels and a battery together?

Yes — adding a battery to solar panels significantly increases the amount of solar energy you use yourself (from around 30%–50% to 60%–80%). Without a battery, excess solar is exported to the grid for just 3–15p/kWh. With a battery, you store it and use it in the evening when electricity costs 24p+/kWh. A combined system typically costs £8,000–£15,000 and can save £800–£1,500+ per year.

Can I charge my EV from solar panels?

Yes. A typical 4kW solar panel system generates enough energy to drive 8,000–10,000 miles per year in an average EV. You'll need a smart EV charger that can be set to charge during peak solar generation. On sunny days, you can charge your EV for free. Combined with a battery, you can store daytime solar and charge your EV in the evening.

How much can I save with solar panels, battery, and EV combined?

A household with solar, battery, and an EV can save £1,500–£3,000+ per year compared to buying all electricity from the grid and fuelling a petrol car. Solar reduces your electricity bill, the battery maximises self-use, and charging your EV from solar costs roughly 2–3p per mile instead of 10–14p per mile for petrol.

What size solar panel system do I need to charge an EV?

For a typical EV covering 8,000 miles per year, you'd need roughly 2,000–2,500 kWh of electricity. A 4kW solar system generates about 3,400–4,000 kWh per year in the UK, which is more than enough. However, you won't always be charging when the sun is shining — a battery helps bridge the gap.

Solar Panels, Battery Storage, and EV Charging — Combined Home Energy Guide | PocketWise

Solar panels, home batteries, and electric vehicles are increasingly being installed together as a complete home energy system. When combined intelligently, they can dramatically reduce your energy costs and carbon footprint.

How the Three Systems Work Together

Time of day	What happens
Morning (sunrise)	Solar panels start generating. Powers your home
Midday (peak sun)	Excess solar charges your home battery AND/OR your EV
Afternoon	Solar still generating. Battery may be full — excess exported
Evening	Battery powers your home. No solar generation
Overnight	If on a smart tariff, cheap electricity charges EV and tops up battery

Costs at a Glance

Component	Typical cost	Annual saving	Payback
Solar panels (4kW)	£5,000 – £7,000	£400 – £700	8–12 years
Home battery (5–10kWh)	£3,000 – £7,000	£200 – £500	8–15 years
EV charger (7kW)	£500 – £1,000	N/A (needed to charge efficiently)	—
Combined system	£8,500 – £15,000	£800 – £1,500+	7–12 years

Solar Panels

System Sizes and Output

System size	Number of panels	Annual generation (UK)	Roof space needed
3kW	8–10	2,500 – 3,000 kWh	~18 m²
4kW	10–12	3,400 – 4,000 kWh	~24 m²
5kW	12–15	4,200 – 5,000 kWh	~30 m²
6kW	15–18	5,000 – 6,000 kWh	~36 m²

Solar Income and Savings

Source of saving	How it works	Value per kWh
Self-consumption	Using solar directly instead of buying from grid	24–30p/kWh saved
Battery storage	Storing excess for evening use	24–30p/kWh saved
Smart Export Guarantee (SEG)	Selling excess to the grid	3–15p/kWh
EV charging	Charging your car from solar	Saves 10–14p/mile vs petrol

Home Battery Storage

Popular Home Batteries

Battery	Capacity	Usable capacity	Cost
Tesla Powerwall 2	13.5 kWh	13.5 kWh	£8,000 – £10,000
GivEnergy 5.2	5.2 kWh	5.2 kWh	£2,500 – £3,500
GivEnergy 9.5	9.5 kWh	9.5 kWh	£4,000 – £5,500
Pylontech US3000C	3.6 kWh	3.6 kWh	£1,500 – £2,000
Fox ESS	5.12 kWh	5.12 kWh	£2,500 – £3,500
SolaX	5.8 kWh	5.8 kWh	£2,500 – £3,500

What Size Battery?

Household type	Evening consumption	Recommended battery
1–2 people	5–8 kWh	5 kWh
3–4 people	8–12 kWh	5–10 kWh
4+ people or EV	12–20 kWh	10–13.5 kWh

Battery Benefits

Benefit	Detail
More self-consumption	Use 60%–80% of solar vs 30%–50% without battery
Evening power	Use stored solar instead of buying grid electricity
Smart tariff arbitrage	Charge on cheap overnight rate (5–10p), use during peak (24–30p)
Backup power	Some batteries provide emergency backup during power cuts
Reduce peak demand	Less strain on the grid

EV Charging from Solar

Charging Costs Compared

Charging method	Cost per kWh	Cost per mile	Annual cost (8,000 miles)
Solar (free)	0p	~0p	£0
Smart tariff overnight	7–10p	~2p	£160
Standard tariff (home)	24–30p	~6–8p	£500–£640
Public charger	40–85p	~10–21p	£800–£1,700
Petrol car	—	12–16p	£960–£1,280

Solar EV Charging Maths

Detail	Value
Average EV efficiency	3.5 miles per kWh
Annual mileage (average)	8,000 miles
Electricity needed	~2,300 kWh
4kW solar generates	~3,500 kWh/year
Percentage needed for EV	~65% of solar output

In practice, you won’t always be charging when the sun shines. A battery helps — or charge at work, and use solar for your home.

Smart EV Chargers

Feature	Why it matters
Solar diversion	Automatically uses excess solar to charge your EV
Scheduled charging	Set charging for overnight cheap-rate periods
App control	Monitor and control remotely
Smart tariff integration	Automatically charges during cheapest periods

Popular options: Zappi (solar diversion built in), Ohme, Pod Point, Wallbox.

Smart Tariffs — The Missing Piece

Smart energy tariffs supercharge your savings:

Tariff	Peak rate	Off-peak rate	Best for
Octopus Go	24–30p	7.5p (12:30am–4:30am)	EV owners
Octopus Intelligent Go	24–30p	7.5p (extended overnight window)	EV owners with compatible car/charger
Octopus Agile	Variable	Sometimes negative (get paid!)	Battery owners who can automate
Octopus Flux	24–30p	Export: 20.3p (peak)	Solar + battery owners
Smart Export Guarantee	N/A	Export: 3–15p	All solar owners

How to Maximise Savings

Strategy	How
Solar + battery + Octopus Flux	Export at 20.3p in peak, charge battery at 14.3p overnight
Solar + EV + Intelligent Go	Charge EV at 7.5p overnight, use solar for home in day
Solar + battery + Agile	Charge battery when prices are lowest/negative, use when highest

Grants and Incentives

Incentive	Detail
0% VAT on solar panels	No VAT on solar panels, batteries, and installation
0% VAT on EV chargers	No VAT when installed with solar panels
Smart Export Guarantee	Get paid for exported solar electricity
BUS grant	£7,500 for heat pumps (not solar, but combines well)
OZEV EV charger grant	Now only for tenants and landlords (£350)

Total Annual Savings

Setup	Estimated annual saving vs grid power + petrol
Solar only	£400 – £700
Solar + battery	£600 – £1,200
Solar + EV (no battery)	£800 – £1,400
Solar + battery + EV	£1,200 – £2,500+
Solar + battery + EV + smart tariff	£1,500 – £3,000+

Summary

Component	Cost	Key benefit
Solar panels (4kW)	£5,000–£7,000	Free electricity during the day
Home battery (5–10kWh)	£3,000–£7,000	Use solar energy in the evening
EV charger	£500–£1,000	Charge car from solar or cheap overnight rate
Smart tariff	Free to switch	Dramatically reduces electricity costs
Combined payback	7–12 years	Savings of £1,500–£3,000+/year

Solar Panels, Battery Storage, and EV Charging — Combined Home Energy Guide