Home energy guide
Home batteries in Guernsey and Jersey: do the numbers work?
A battery can still pay its way in the Channel Islands, but the gap between cheap and normal rates is narrower than on GB smart tariffs, so the savings are smaller. Here's how the sums look on each island.
Last updated:
Work out your own numbers with the home battery calculator →
Guernsey: Super Economy 12
Guernsey's Super Economy 12 tariff gives you 12 cheap hours a day at about half the normal price. That's what a battery can play with. (No VAT or GST in Guernsey; prices from 1 July 2026.) Check the exact low-rate hours with Guernsey Electricity; we haven't listed them here.
See the numbers
| Tariff | Rate |
|---|---|
| Standard | 26.01p per kWh |
| Super Economy 12, low rate (12 hours) | 13.12p per kWh |
| Super Economy 12, normal rate | 27.77p per kWh |
| Super Economy 12 standing charge | £89.35 per quarter |
| Buy Back Tariff (exports) | 9.90p per kWh |
Charging cheap, using later
A 9.5 kWh battery used this way saves about £313 a year. At £6,500, that's roughly 21 years to pay back, longer than a typical battery lasts. A cheaper battery improves this.
See the numbers
Each kWh charged at 13.12p and used instead of 27.77p, at 90% efficiency: 27.77p − 13.12p ÷ 0.9 ≈ 13.2p. 250 cycles × 9.5 kWh = 2,375 kWh a year ≈ £313.
Storing solar
This is where Guernsey batteries shine. Exporting earns only 9.90p a unit, so keeping solar for yourself is worth about 15p a unit, more than in Great Britain. Storing 1,000 kWh of spare solar a year saves about £150.
See the numbers
26.01p (Standard rate) − 9.90p ÷ 0.9 ≈ 15.0p per kWh, compared with about 13p in Great Britain, where typical export rates are higher.
Don't just add the two together: a battery full of solar can't also be filled at the low rate. The battery calculator lets you plug in Guernsey's night, day and export rates.
Jersey: Economy 7
Jersey's Economy 7 night rate is about half the day rate. But the sums are tighter: a battery saves about £242 a year, meaning roughly 27 years' payback at £6,500. On these rates, a battery on its own is hard to justify in Jersey unless it's cheap or paired with solar.
See the numbers
| Tariff | Incl. GST | Excl. GST |
|---|---|---|
| General Domestic | 22.20p | 21.14p |
| Economy 7 day | 23.22p | 22.11p |
| Economy 7 night | 11.74p | 11.18p |
| Service charge, single phase (General Domestic / Economy 7) | 24.21p / 28.73p a day | 23.06p / 27.36p a day |
Rates include 5% GST. Saving per kWh: 23.22p − 11.74p ÷ 0.9 ≈ 10.2p. 2,375 kWh a year ≈ £242 including GST (about £230 excluding GST).
Economy 7 also has a higher daily charge and a pricier day rate than General Domestic, so switching just for a battery only works if you shift enough use.
For storing solar in Jersey, it depends on the export rate, which we couldn't verify today. Ask Jersey Electricity before you buy.
Why payback takes longer on the islands
- The gap between cheap and normal rates (about 14.7p in Guernsey, 11.5p in Jersey) is narrower than on GB smart EV tariffs (about 19.8p, using the cap average and 6.5p).
- Batteries and fitting may cost more on the islands because of shipping and fewer installers. We haven't verified island prices.
When a battery makes more sense on the islands
- with solar in Guernsey, where the low buy-back rate makes storing solar more valuable;
- if you value backup during power cuts and buy a battery that does that;
- if battery prices fall, because payback is very sensitive to price.
Compare with the GB picture in our UK battery savings guide, and read about island tariffs in our Guernsey and Jersey tariffs guide.
Frequently asked questions
Is a home battery worth it in Guernsey?
On Super Economy 12 (13.12p low, 27.77p normal) a 9.5 kWh battery cycled 250 times saves about £313 a year. With solar, storing surplus instead of selling at 9.90p is worth about 15p per kWh, which helps.
Is a home battery worth it in Jersey?
Hard to justify on Economy 7 alone: about 10.2p per kWh saved, or roughly £242 a year for a 9.5 kWh battery. It is more attractive with solar or a lower battery price.
Do Jersey electricity prices include GST?
Yes. Jersey Electricity says its rates include GST. Divide by 1.05 to get the price before 5% GST.
What does Guernsey Electricity pay for exported solar?
The Buy Back Tariff is 9.90p per kWh, unchanged in the July 2026 tariff changes.
Related guides
- Home battery savings: night rates and stored solar
- How much does a home battery cost in the UK?
- What size home battery do I need?
- Is a home battery worth it without solar panels?
- Tariffs for home batteries: overnight, three-rate and export tariffs
- All home-energy calculators
Sources (checked 27 October 2026 unless stated)
- Guernsey Electricity: tariffs from 1 July 2026 and Guernsey Gazette tariff notice: Standard, Super Economy 12, standing charge, Buy Back Tariff (from 1 July 2026)
- Jersey Electricity: General Domestic, Economy 7 and Domestic Tariffs Explained (1 March 2026): General Domestic, Economy 7 and service charges (from 1 March 2026)
- Octopus Energy: Intelligent Octopus Go: from 6.5p/kWh (checked 31 Oct 2026)
- Ofgem: price cap 1 Oct–31 Dec 2026 (published 26 Aug 2026): 26.32p/kWh
- Jersey Electricity export rate: not verified
- Battery and installation prices in the Channel Islands: not verified
- Round-trip efficiency, cycles and £6,500 price: our assumptions