Guide · Batteries
We fit both · Updated October 2026
Short answer
Fox ESS if you want the lowest fitted price; Sigenergy if you want your battery, EV charger and heat pump built as one system.
Both run from an app on your phone: FoxCloud for Fox ESS, mySigen for Sigenergy. We fit both. Battery only, a Fox ESS EP12 is from £2,790 fitted and a Sigenergy from £3,190.
What matters most to you?
Fitted by us in Romford and Bedford
Lowest priceOur pick for you
Pick this if you want the evening covered at a price that is easy to say yes to.
We fit it, including in Leighton Buzzard
One system for it allOur pick for you
Pick this if you want solar, battery and car charging run as one system.
Prices are fitted, at 0% VAT. What the two prices mean
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MCS-certified installer · Cert. no. NAP/79987/26/1
Most people fall into one of three camps. Find yours and you have your answer.
You want the evening covered, and a price that is easy to say yes to.
→ Fox ESS. It is our most-fitted battery, for exactly this reason.
You would rather see your solar, battery and car charging in one place, run as one system.
→ Sigenergy. That one system is what you are paying for.
Your electricity use is growing. You want the system to grow with it, without starting again.
→ Sigenergy, sized with room left in the stack.
The prices are in the cards above. Here is everything else that changes how each one fits your home.
| What | Fox ESS | Sigenergy |
|---|---|---|
| Value per kWh stored | Leads | Close behind |
| How it grows | Add another unit of the same size. One EP12 holds 11.52 kWh; it stacks to 23 or 34.5 kWh. | Add another battery module to the stack. The more flexible of the two. |
| EV charger | Fox ESS charger, run from the FoxCloud app with your battery | Sigenergy charger, run from the mySigen app with your battery |
| The app | Plain, and perfectly capable | Stronger. It is the whole point of the system |
| Where it goes | Floor-standing, rated for outdoors | Wall or floor stack, rated for outdoors |
| On top of the warranty | Our IWA insurance-backed workmanship guarantee, with either one | |
A kWh (kilowatt-hour) is a unit of electricity. The more kWh a battery holds, the longer it can run your home.
Each card shows two prices, because they are two different jobs.
We add the battery to the hybrid inverter you already have. A hybrid inverter is one built to work with a battery. Your inverter stays.
We fit the battery with a new hybrid inverter, for example replacing an old or failed one. It works with or without solar panels.
0% VAT. Your exact price is fixed after a free survey — it depends on where the battery goes, the cable run and your consumer unit. The price we quote is the price you pay.
Both come in our solar and battery packages. These are the starting prices.
| Battery | Package | From |
|---|---|---|
| Fox ESS | Smart: 10 panels + 5.76 kWh EP6 | £6,890 |
| Fox ESS | Plus: 10 panels + 11.52 kWh EP12 | £7,990 |
| Sigenergy | 12 panels + 8.8 kWh (one battery) | £11,990 |
| Sigenergy | 15 panels + 17.5 kWh (two batteries) | £13,990 |
The Fox ESS packages use 10 × 470 W all-black panels. Every package price is at 0% VAT and based on one roof elevation with a single scaffold lift; extra faces or scaffolding are quoted at survey.
How our prices work: package prices are for panels on one roof face with a single scaffold lift. Your fixed price comes with your free roof design. It is based on your roof type, how many roof faces the panels sit across, the scaffolding needed and where the battery goes. No guessing, no surprises on the day.
Both are good batteries. Each has one thing that might put you off.
The app is plain, and the EV charger lives in its own app. If you want everything on one screen, that will bother you.
It costs more for the same storage. It also works best when the charger and inverter are Sigenergy too. The one system is its strength, and it is also a commitment.
Neither is a mistake. The only wrong choice is the one that does not match how your home will use electricity in three years. That is what we work out with you at your free roof design visit.
We fit both, so this comes from our own jobs, not a spec sheet.
It charges, it discharges, and the evening is covered. The app gets opened in the first week and rarely after. We take that as a compliment.
Especially with a charger fitted. Seeing the car, the battery and the roof on one screen is what they bought, and they say so.
Fox ESS. The EP12 is the battery we fit more than any other.
Yes, with both. We plan for it in your design, so adding one later is simple.
Fox ESS, for the same storage. Our Plus package — 10 panels and an 11.52 kWh EP12 — is from £7,990 installed. A Sigenergy battery starts at £3,190 added to your system, against £2,790 for a bigger EP12. With Sigenergy, expect to pay more for the same kWh.
Sigenergy, if you want the charger, battery and solar designed as one system. Fox ESS works with an EV charger too — we fit Fox ESS chargers, and they run from the same FoxCloud app as the battery.
Sigenergy grows by adding another battery module to the stack. Fox ESS grows by adding another unit of the same size, EP12 to EP12.
We fit Fox ESS more often. Most homes want the most storage for the money and a system that just works. We recommend Sigenergy when a household is clearly heading towards an EV and a heat pump, and wants one system for all of it.
Ten years on both battery systems. On top of that, you get our IWA insurance-backed workmanship guarantee.
Get started
Your free roof design and fixed price — we recommend the system that fits how you use electricity, not the one with the biggest margin.
0% VAT on solar & battery until March 2027