The honest answer
Fox ESS publishes no UK prices and does not sell to homeowners direct. Its own Get a Quote page says it will pair you with a Premier Partner or a selected Approved Partner — so the number you pay is set by whoever installs it, from a specification written for your house.
Inventing a figure to fill that gap would only make this page less useful. Here instead is which decisions move the money, so that when two quotes land on your kitchen table you can tell whether they are for the same system. For the record: we install Fox ESS battery and hybrid-inverter systems (including the Fox Cube battery) and have two complete installs documented on our YouTube channel. Andy Pemberton surveys and specifies every system we quote.
Why there is no list price
Fox ESS is a range, not a product. The UK site lists three residential battery ranges — EQ (EQ2900, EQ4300, EQ4800, EQ5000), EP (EP6 and EP12) and the CQ7 — plus three all-in-one systems and five hybrid inverter families. Two households both “getting a Fox battery” can be buying wildly different amounts of hardware.
Fox also sells through distributors — Segen, UK Greentech, CEF and Midsummer as Strategic Partners, plus three Approved ones — so what an installer pays depends on their trade route as much as on the kit.
What actually drives the price
How many kWh, and from which range
The biggest lever by a distance. The EQ range is a floor-mounted modular stack: on the single-phase H1-G2 and K Series inverters, EQ2900 modules are 2.88 kWh each and run from 2 to 7 (5.76 to 20.16 kWh), EQ4800 modules are 4.66 kWh and run from 2 to 9 (9.32 to 41.94 kWh), and EQ5000 modules are 4.92 kWh and run from 2 to 6 (9.84 to 29.52 kWh). Every extra module is a clean extra line on the quote, which makes EQ the easiest range to size to a budget.
The EP range is bought in blocks instead — EP6 at 5.76 kWh, EP12 at 11.52 kWh, one to four batteries — and the CQ7 is 7.02 kWh a module, up to 49.14 kWh. All three are rated at 90% depth of discharge, so compare usable energy, not headline capacity.
Which inverter, and whether you already have solar
The single-phase H1-G2 and AC1-G2 come in 3, 3.7, 5 and 6 kW, dual MPPT with a 200% PV oversize ratio, and run DC or AC coupled — if you already have a working solar inverter, AC coupling is usually cheaper because nothing on the roof gets touched. Bigger arrays move you to the KH/KA Series (7 to 10 kW), which Fox also sells as “Battery Ready – Install now, without batteries”, and three-phase means the H3 Smart, 5 to 15 kW, which brings more board work with it. The all-in-ones are the other route, but the first-generation Evo AIO's integrated 10.24 kWh battery expands by parallel installation of whole extra Evo units, so for “start small, grow later” a stack is cheaper.
Backup: the biggest yes-or-no on the sheet
Two different things get sold as backup. The inverter's own EPS output switches in under 10 milliseconds and gives you a protected circuit. Whole-home backup is a separate box — the EPS-BOX-SP gateway, which isolates the property and restores power from battery and solar after a changeover of about 2 to 3 seconds, subject to system sizing. Decide before you ask for prices, because adding it later means the board work gets done twice.
And the parts that are nothing to do with Fox
Scaffolding, consumer unit work and cable route length are what make two quotes for identical hardware differ. The EQ stack is floor-mounted and Fox's warranty conditions require 300 mm of clearance around the pack, so a garage wall near the board is a different day to the far corner of the house.
What is in our quotes
We itemise, because on this product the specification is the price. A Fox quote from us sets out the survey and design; the hardware by name (which inverter and what kW, which battery range, how many modules, gateway in or out); the electrical work; the network operator application and commissioning paperwork; commissioning, FoxCloud set-up and handover; and the warranty registration.
That last one matters more than it looks. Fox registers inverter and battery warranties separately, and the Hybrid and K Series only get their further 60 months free — ten years instead of five — if the unit is registered within 36 months of the date of manufacture and connected to Fox Cloud with a Fox datalogger. Miss it and you quietly own a five-year inverter. We are MCS Certified and NAPIT Registered with 500+ five-star reviews across Checkatrade and Google, none of which makes us the cheapest quote you will get.
0% VAT, and the date it ends
HMRC's VAT Notice 708/6 zero-rates the installation of certain specified energy-saving materials from 1 May 2023 to 31 March 2027, reverting to the 5% reduced rate from 1 April 2027, and since 1 February 2024 electrical storage batteries in residential accommodation qualify — retrofits to existing microgeneration, standalone batteries charged from the grid, and batteries fitted alongside new solar.
So a Fox battery fitted today should be zero-rated, and a quote showing VAT on the battery work is worth a question. That relief has an end date, and 31 March 2027 is the reason to turn “at some point” into a date.
Why a Fox quote usually lands under a Powerwall quote
A Tesla Powerwall 3 is one fixed unit with 13.5 kWh of usable energy, and our own quote guidance is from £8,500 installed — ALPS's figure, not Tesla's, because Tesla publishes no UK price. What matters here is that there is nothing smaller to buy: the entry point is a whole Powerwall.
Fox's entry point sits much lower down. A two-module EQ2900 stack is 5.76 kWh on a 3.7 or 5 kW hybrid inverter — well under half the storage, so of course it costs less. Most times somebody tells us the Fox quote came in cheaper, the two quotes are simply not for the same amount of battery.
Match the capacity and the gap closes fast — three EQ4800 modules is 13.98 kWh, and whole-house backup adds the EPS-BOX-SP on top. Fox wins on cost at the small end and the staged end — you can buy 5.76 kWh, which Tesla does not offer — but it does not automatically win on labour. Our Fox ESS vs Tesla Powerwall 3 post runs the two side by side.
How to compare two Fox ESS quotes
Comparison is about matching the specification, not the total. Convert both quotes to usable kWh at 90% depth of discharge, check which inverter is on each and whether the EPS-BOX-SP is a line item, and ask who makes the network application and whether scaffolding is priced or provisional. Then compare the warranty, because it differs by range and it is part of the price:
| Battery | Nominal | Product warranty | Performance guarantee |
|---|---|---|---|
| EQ2900 | 2.88 kWh | 144 months | ≥70% for 12 years or 12.15 MWh |
| EQ4800 | 4.66 kWh | 144 months | ≥70% for 12 years or 17.47 MWh |
| EQ5000 | 4.92 kWh | 144 months | ≥70% for 12 years or 18.45 MWh |
| EP6 | 5.76 kWh | 120 months | ≥70% for 10 years or 21.6 MWh |
| EP12 | 11.52 kWh | 120 months | ≥70% for 10 years or 43.19 MWh |
Those terms run from installation but are capped at 149 months from manufacture on the EQ range and 125 on the EP range, and the guarantee ends at the years or the throughput, whichever comes first. We will not put a number against the CQ7, because Fox's UK page states none. One clause is worth reading twice: claims are made by the installer, and installation by a non-accredited installer is an exclusion — so the cheapest quote is worth little if the company behind it is gone by year six.
Our take from fitting them
We have two complete Fox installs filmed end to end: 9.6 kW of solar with a Fox Cube battery at Ingleby Barwick and a Fox Cube battery with JA Solar on a garage roof. One note on that name: “Cube” is Fox's ECS generation, which is not in the current UK line-up or battery warranty policy, so anything quoted today will be EQ, EP, CQ7 or an all-in-one.
What those jobs taught us about cost: the battery is rarely what decides the day. The consumer unit, the cable route and the network operator's paperwork do, whatever badge is on the box. When a quote is unusually cheap, that is normally where the difference is hiding.
Where we would tell you not to spend: do not buy the biggest stack the range allows simply because it is modular — size it to what you genuinely shift overnight, because adding modules later is the easy part. And do not pay for a smart-tariff optimiser, because Fox's Capture AI is included free with all Fox ESS systems and works with all UK suppliers and tariffs. If you want the fewest boxes on the wall, look at the Powerwall 3; for DC car charging in the same product, the Sigenergy SigenStor. With no solar yet, get the array right first — see solar panel installation, battery storage or the buying guide.
Ask us for a fixed price
The survey is free and the price that follows it is fixed, itemised and specific to your property — on a product with no list price, the only kind of number worth having.
We install across Teesside, County Durham and North Yorkshire from our base in Yarm. How far we travel depends on the job — just ask.
Send us your postcode, roughly what you spend on electricity and whether backup matters through our contact page, and Andy will come back with a configuration and a number. If the honest answer is “a smaller stack, and put the difference into panels”, he will say that. More reading: the Fox ESS installer page and the Fox Cube battery review.