The Fox ESS EP12 Plus is an 11.52 kWh High Voltage Battery LiFePO₄ solar battery designed for UK homes and small businesses pairing with Fox ESS hybrid or AC-coupled inverters. With a 384V nominal voltage, 90% depth of discharge (10.37 kWh usable) and ≥95% round-trip efficiency, it delivers one of the most energy-dense and efficient high-voltage storage modules at this capacity. The integrated self-heating element allows safe charging in cold installations — garages, outbuildings and outdoor enclosures — while the IP65 rating makes it fully weatherproof for permanent outdoor mounting. Built-in fire protection is included as standard. Up to 4 units can be combined in parallel via the Fox EP Junction Box, scaling to 46.08 kWh from a single inverter port. This is Fox ESS's first slimline wall-mountable large-capacity battery, at just 185mm depth.
11.52 kWh
Nominal Capacity
10.37 kWh
Usable (90% DoD)
≥95%
Round-Trip Efficiency
✅ EP11 + EP12 Compatibility: The EP12 Plus can be mixed with EP11 batteries in the same system, provided all batteries are updated to firmware V1.010 or newer. For best performance, Fox ESS recommends using the same model throughout. EP12 batteries are not compatible with EP6 or other lower-voltage EP series units.
Fox ESS EP Series — Range at a Glance
| Model |
Nominal |
Usable |
Voltage |
Op. Range |
Max I (C/D) |
Max Capacity |
| EP6 Plus |
5.76 kWh |
5.18 kWh |
192 V |
174–219 V |
30A / 30A |
23.04 kWh |
| EP12 Plus ✓ |
11.52 kWh |
10.37 kWh |
384 V |
348–438 V |
30A / 30A |
46.08 kWh |
All models: LiFePO₄, IP65, 90% DoD, ≥95% RTE, 10-year warranty, CAN comms. This listing covers the highlighted row.
Key Features & Technology
LiFePO₄ Chemistry — Safe, Long-Life Lithium
Lithium iron phosphate (LFP) cells are the safest lithium chemistry available — inherently resistant to thermal runaway due to the chemical stability of the iron-phosphate bond. Unlike NMC or NCA cells, LFP does not release oxygen when heated, eliminating the risk of self-sustaining combustion. This makes it the preferred chemistry for home energy storage in enclosed spaces such as garages, utility rooms and outdoor enclosures.
Integrated Self-Heating — Reliable Cold-Weather Performance
The built-in warming function pre-heats the battery cells before charging begins when ambient temperature is low. This is critical for LFP cells, which can experience lithium plating and reduced capacity if charged at sub-zero temperatures. The integrated heater allows the EP series to charge safely and effectively in cold UK installations including garages, outbuildings and outdoor enclosures without performance degradation or cell damage.
90% Depth of Discharge — Maximum Usable Energy
With a 90% depth of discharge (DoD), the EP series delivers the vast majority of its nominal capacity as usable energy — significantly more than batteries limited to 80% DoD. Round-trip efficiency of ≥95% means minimal energy is lost during each charge/discharge cycle.
IP65 — Certified for Outdoor and Indoor Installation
IP65 ingress protection means the battery is fully protected against dust ingress and low-pressure water jets in any direction. Combined with the integrated heating element, this makes the EP series genuinely suitable for outdoor wall or floor mounting — no additional weatherproof enclosure is required. Operating temperature range: charge 0°C to 55°C, discharge -10°C to 55°C.
Modular and Scalable — Expand Up to 4 Units in Parallel
Each EP module can be combined with up to 3 additional units (4 total) using the Fox ESS EP Junction Box (FE-JUNBOX-HV), allowing the system to grow as energy needs increase — without replacing the inverter. Modules added later are automatically integrated into the system through the BMS.
Wall or Floor Mounting — Flexible Installation
The compact, slim-depth enclosure (185mm deep) can be wall-mounted or floor-standing, giving installers full flexibility to work with the available space. The slimline profile keeps the installed footprint minimal in tight utility rooms, garages or plant rooms.
Fire Protection — Built-In Safety System
The EP12 Plus includes a factory-fitted fire protection function as standard. This active fire suppression capability adds a critical layer of safety beyond the inherent thermal stability of LFP chemistry — important reassurance for home and commercial installations in enclosed or attached spaces.
CAN Communication — Seamless Fox ESS Inverter Integration
CAN bus communication provides direct, high-speed BMS data exchange between the battery and compatible Fox ESS inverters (H1, KH, H3, H3 Smart, H3 Pro and US series). This enables intelligent charge/discharge management, accurate state-of-charge reporting, and full integration with the Fox ESS monitoring app. 5 LED status indicators on the front panel give at-a-glance system status.
10-Year Warranty and >6,000 Cycle Rating
Fox ESS backs the EP series with a 10-year warranty and rates the cells for more than 6,000 charge/discharge cycles. Cycling once per day, 6,000 cycles represents over 16 years of daily use — providing a strong long-term return on investment and low lifetime cost per kWh stored.
Certified to International Safety Standards
The EP series holds IEC 62619 (lithium-ion cell safety), EN IEC 61000-6-1/2/3/4 (EMC) and UN 38.3 (transport safety) certifications — confirming compliance with European and international safety requirements for residential and commercial battery storage.
Technical Specifications — Fox ESS EP12 Plus (Datasheet V1.1, Oct 2025)
| Electrical Characteristics |
| Battery Type |
LFP (LiFePO₄) |
| Nominal Energy |
11.52 kWh |
| Usable Energy (90% DoD) |
10.37 kWh |
| Nominal Voltage |
384 V |
| Operating Voltage Range |
348 – 438 V |
| Max. Charge / Discharge Current |
30 A / 30 A |
| Recommended Charge Current |
15 A |
| Peak Discharge Current |
65 A (@ 60s) |
| Peak Charge Current |
36 A (@ 5s) |
| Round-Trip Efficiency |
≥ 95% |
| Depth of Discharge |
90% |
| Communication |
CAN |
| Display |
LED × 5 |
| Scalability |
Max. 4 units in parallel |
| Operating Conditions |
| Operating Temperature — Charge |
0°C to +55°C |
| Operating Temperature — Discharge |
-10°C to +55°C |
| Storage Temperature |
-10°C to +40°C |
| Relative Humidity |
5% – 95% (no condensation) |
| Max. Altitude |
3,000 m |
| Installation Location |
Indoor or Outdoor |
| Cooling Method |
Natural convection (passive) |
| Mechanical |
| Dimensions (W × H × D) |
710 × 640 × 185 mm |
| Weight |
98 kg |
| Mounting |
Wall or floor |
| Protection & Safety |
| Ingress Protection |
IP65 |
| Fire Protection Function |
Yes — integrated (standard on EP12 Plus) |
| Warming Function |
Optional (with heating element variant) |
| Certifications |
| Safety |
IEC 62619 |
| EMC |
EN IEC 61000-6-1/2/3/4 |
| Transport |
UN 38.3 |
| Warranty & Inverter Compatibility |
| Warranty |
10 years |
| Cycle Rating |
> 6,000 cycles |
| Compatible Inverters |
Fox ESS H1, KH, H3, H3 Smart, H3 Pro, US series |
| Max System Capacity (per inverter port) |
46.08 kWh (4 × EP12 Plus) |
| Junction Box Required (2+ units) |
Fox ESS FE-JUNBOX-HV |
ℹ Installation Note: The EP12 Plus must be installed by a qualified electrician in accordance with BS 7671, the Fox ESS installation guide and any applicable DNO G98/G99 notification requirements. A
Fox ESS Junction Box (FE-JUNBOX-HV) is required when installing 2 or more units in parallel. Ensure all batteries in a parallel system are on firmware V1.010 or newer if mixing with EP11 units. For technical support contact Fox ESS UK at
www.fox-ess.com.
Frequently Asked Questions
How much usable energy does the EP12 Plus actually deliver?
At 90% depth of discharge, the EP12 Plus delivers approximately 10.37 kWh of usable energy per cycle. Combined with ≥95% round-trip efficiency, this means a typical daily cycle (charge from solar or grid, discharge to home) wastes less than 5% of the stored energy in conversion losses — one of the most efficient battery storage ratios available at this capacity.
What inverters is the EP12 Plus compatible with?
The EP12 Plus is compatible with the full range of Fox ESS high-voltage hybrid and AC-coupled inverters: H1, KH, H3, H3 Smart, H3 Pro and US series. It communicates via CAN bus and integrates directly with the Fox ESS monitoring app. It is not compatible with third-party inverters — always confirm inverter compatibility before purchase.
Do I need a Junction Box to install multiple EP12 units?
Yes. When installing 2, 3 or 4 EP12 units in parallel, the Fox ESS EP Junction Box (FE-JUNBOX-HV) is required. A single EP12 does not require the junction box. The junction box enables safe parallel connection and allows the BMS to manage all modules as a single battery bank. Maximum system capacity with 4 units: 46.08 kWh.
Can the EP12 be installed outdoors in a UK climate?
Yes. The EP12 Plus is IP65 rated for full dust and water-jet protection, and the integrated self-heating element keeps the cells warm enough to charge safely even when the ambient temperature drops close to or below freezing. The operating temperature range for discharge is -10°C to +55°C — covering the full range of UK outdoor temperatures in all seasons.
Can EP12 and EP11 batteries be used together in the same system?
Yes, with a caveat. EP11 and EP12 batteries can be mixed in the same system, but all batteries must be updated to firmware V1.010 or newer before mixing. Fox ESS still recommends using the same model throughout for optimal performance. EP12 batteries are not compatible with EP6 or other lower-voltage EP series units.
Related Products
Fox ESS EP6 Plus 5.76kWh
Half-capacity 192V variant — for smaller storage requirements
Fox ESS EP Junction Box (FE-JUNBOX-HV)
Required when paralleling 2–4 EP12 units
Fox ESS H3 Pro Hybrid Inverter
Compatible high-power hybrid inverter for EP12 systems
