Fox ESS EP11
A 10.36 kWh high-voltage LFP battery from Fox ESS, scalable to four units, with a 10-year performance warranty.
- Best for high-voltage stacking
- Installed battery
- 10.36-41.6 kWh
- 10-year warranty
- Energy: 10.36 kWh nominal per unit, 90% depth of discharge, up to four units (41.6 kWh).
- A battery only: it works with Fox ESS H1, KH, H3, H3 Smart and H3 Pro hybrid inverters.
- High-voltage (384 V nominal), IP65, floor or wall mounted, indoors or outdoors.
- UK warranty: 10 years or 33.4 MWh, whichever comes first, to 70% of nominal energy.
Not tested by us
We have not tested the Fox ESS EP11. The figures on this page come from the sources listed at the end of the page, checked on 10 November 2026, and we do not show prices. "Best for" is based on what the maker says the product is designed for, not on our own tests.
Key figures
10.36 kWh
Per unit
41.6 kWh
Maximum, 4 units
10 years
UK performance warranty
Specifications
Last checked on 10 November 2026. The grey text under each name explains what the value means.
| Specification | Value |
|---|---|
| Storage | |
| CapacityHow much energy the battery stores. Bigger means longer runtime or more of your own solar power used later. | 10.36 kWh nominal per unit; up to 41.6 kWh with four units |
| Usable capacityThe part of the stored energy you can actually use. It is lower than the nominal capacity. | Not stated (the datasheet gives 90% depth of discharge) |
| Depth of dischargeHow much of the battery can be emptied without harming it. 90% means 10% is kept in reserve. | 90% |
| Battery chemistryLFP (lithium iron phosphate) cells are known for long life and stable behaviour with heat. | LFP (LiFePO4) |
| Cycle lifeHow many full charge and discharge cycles the cells are rated for before they hold less than the stated share of their original capacity. | Not stated in the datasheet. The UK warranty is set by throughput: 33.4 MWh |
| ExpansionExtra battery units that add storage to the same system. | Up to four units connected in parallel |
| Power | |
| Charge and discharge powerHow fast the battery can take in and give out energy. It sets how many devices it can serve at once. | Maximum charge and discharge current 27 A (13.5 A recommended for charging); peak discharge 65 A for 60 s and peak charge 32.4 A for 5 s at 384 V nominal. Fox ESS gives amps, not kW |
| Round-trip efficiencyThe share of the energy you put in that comes back out. The rest is lost as heat. | At least 95% (battery pack) |
| Backup in a power cutWhether it can keep selected circuits running during a grid outage. | Depends on the inverter: the battery itself is not an inverter |
| Solar | |
| Solar inverterTurns the DC power from solar panels into AC for the home. Built in means no separate solar inverter is needed. | None: this is the battery only. It needs a Fox ESS hybrid inverter (H1, KH, H3, H3 Smart or H3 Pro series) |
| Connection and housing | |
| Grid connectionThe supply type it is built for. Check it matches your home's supply. | Not applicable: the battery connects to an inverter (384 V nominal, 348-438 V operating range, high-voltage DC) |
| Dimensions (W × H × D)Width, height and depth of the unit, so you can check that it fits. | The datasheet lists 380 × 625 × 147 mm (50.5 ± 2 kg) and 710 × 625 × 147 mm (99 ± 2 kg); it does not label which is which, so confirm with Fox ESS |
| WeightMatters for lifting, wall mounting and moving it. | 50.5 ± 2 kg or 99 ± 2 kg (see dimensions) |
| Protection ratingIP ratings show protection from dust and water. IP55 and IP65 are rated for outdoor-style exposure; check the installation guidance. | IP65, indoor or outdoor, floor or wall mounting, natural convection cooling |
| Operating temperatureThe range it is rated to work in. Cold and heat can reduce performance. | Charging 0 to 55 °C; discharging -10 to 55 °C; storage 0 to 35 °C |
| Battery heatingA built-in heater that lets the battery charge in cold weather. | A warming function is listed; Fox ESS gives no details |
| ConnectivityHow you monitor and control it, usually through an app. | CAN to the inverter; 5 LED status display |
| CertificationsSafety and grid standards the maker says the product meets. | IEC 62619, EN IEC 61000-6-1/2/3/4 and UN 38.3 |
| Warranty | |
| WarrantyThe period the maker covers. Read the terms: conditions and capacity guarantees differ. | UK and Ireland: 10 years or 33.4 MWh throughput, whichever comes first, with at least 70% of nominal energy retained. Workmanship warranty 60 months, with a free 60-month extension if registered within 36 months of manufacture and connected to Fox Cloud |
Compatible with
What Fox ESS says this product works with. Anything not listed here is not confirmed.
- Inverters
- Fox ESS lists the H1, KH, H3, H3 Smart, H3 Pro and US series.
- Expansion
- Up to four EP11 units in parallel.
- Mounting
- Floor or wall, indoors or outdoors.
Rules where you live
An installed battery normally needs a qualified electrician, and in many countries you must also tell your grid operator, especially if it can export. Rules, incentives and tax treatment differ by country: see our country guides for what applies where you live.
Strengths and things to check
Strengths
- High-voltage design that scales to 41.6 kWh
- Battery pack efficiency of at least 95%
- IP65, indoor or outdoor
- Warming function for cold conditions
- 10-year performance warranty in the UK
Worth checking before you buy
- A battery only: you need a compatible Fox ESS inverter
- Only 90% depth of discharge
- The warranty also has a throughput cap (33.4 MWh)
- The datasheet does not label which size and weight apply to which configuration
Change log
We record changes to this page here, so you can see when figures such as the warranty were last updated.
- 10 November 2026
- Page published. Warranty at publication: 10 years or 33.4 MWh (Fox ESS UK battery warranty policy V4.2). Datasheet used: EP11 V1.5, 23 October 2025.
Where this information comes from
We have not tested the EP11. Every figure above comes from the Fox ESS EP11 datasheet (V1.5, October 2025) and Fox ESS's UK and Ireland battery warranty policy (V4.2), last checked on 10 November 2026. A value that the sources do not state is shown as not stated.
We do not show prices, because they depend on the installer's quote.
- Manufacturer Fox ESS EP11 datasheet V1.5
- Manufacturer Fox ESS battery warranty policy, UK and Ireland (V4.2)
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Common questions about Fox ESS EP11
How much can the Fox ESS EP11 store?
Each unit is 10.36 kWh nominal at 90% depth of discharge. Fox ESS lists up to four units in parallel, 41.6 kWh.
Which inverter does the EP11 need?
Fox ESS lists its H1, KH, H3, H3 Smart, H3 Pro and US series as compatible. Ask your installer which exact model suits your home.
What does the UK warranty cover?
Fox ESS's UK and Ireland policy gives 10 years or 33.4 MWh throughput, whichever comes first, with at least 70% of nominal energy retained. It has conditions, so read the policy.
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