The Fox ESS EP5-H is a high-voltage, 5.18kWh LiFePO₂ (lithium iron phosphate) battery module built on Fox ESS's established EP platform, with one key difference from the standard EP5: a built-in battery warming element. This automatically brings the cells up to temperature in cold conditions, protecting charge performance and battery health through UK winters — particularly useful for garages, outbuildings, and unheated outdoor installations.
The EP5-H is compatible with the full range of Fox ESS 1-phase and 3-phase Hybrid and AC-coupled inverters (H1, KH, H3, H3-Pro and US series), and is scalable up to 20.8kWh by paralleling up to four units. Its slimline 147mm-deep wall-mounted enclosure (or optional floor mounting) keeps the installation footprint compact, while an IP65 rating and -25°C to 55°C storage tolerance support both indoor and outdoor siting.
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5.18kWh
Nominal Energy
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90%
Depth of Discharge
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≥95%
Round-Trip Efficiency
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IP65
Ingress Protection
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4 Units
Max. Parallel
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10 Yr
Warranty (w/ Reg.)
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Good to Know
The battery warming function automatically activates when cell temperature approaches 0°C, warming the pack back to a safe operating range before charge or discharge resumes. This is separate from the battery's standard discharge operating range, which extends down to -10°C without heating.
Please Note
The EP5-H can be paralleled with standard (non-heated) EP5 units in the same stack. However, in a mixed system the self-heating element in the EP5-H is disabled — all units in a mixed stack lose access to the warming function. For cold-climate or unheated installations, AIZO recommends specifying EP5-H throughout the stack.
Cold-Climate Reliability
The integrated heating element is engineered specifically for outdoor and unheated installations, where regulatory trends increasingly favour external battery siting. It protects the LiFePO₂ cells from the charge/discharge degradation that occurs when lithium batteries operate too close to freezing.
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High Round-Trip Efficiency
A ≥95% battery pack round-trip efficiency means less energy is lost converting stored solar into usable household power, translating directly into more self-consumed generation and a faster return on the wider PV investment.
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Deep 90% Depth of Discharge
Fox ESS rates the EP5-H to 90% DoD, allowing the vast majority of the 5.18kWh nominal capacity to be used on every cycle without compromising the battery's long-term health or warranty terms.
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Scalable to 20.8kWh
Up to four EP5-H units can be paralleled via the Fox HV Junction Box, taking a single system to 20.8kWh of usable storage — and up to eight units when paired with the Fox H3 Pro hybrid inverter, ideal for larger households or phased system growth.
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Compact, Flexible Mounting
At just 147mm deep, the slimline wall-mounted enclosure suits installations where wall or floor space is limited. Floor mounting is also supported, giving installers flexibility across a range of plant room and garage layouts.
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Built-In Fire Suppression
The EP5-H includes built-in fire suppression technology alongside the standard battery management protections, adding a further layer of safety assurance for both indoor and outdoor installations.
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| Battery |
| Battery Type |
LiFePO₂ (LFP) Prismatic Cell |
| Nominal Energy |
5.18 kWh |
| Nominal Voltage |
192 V |
| Operating Voltage Range |
174 – 219 V |
| Max. Charge/Discharge Current |
27 A* |
| Recommended Charge Current |
13.5 A |
| Peak Discharge Current |
65 A @ 60s |
| Peak Charge Current |
32.4 A @ 5s |
| Battery Pack Round-Trip Efficiency |
≥ 95% |
| Depth of Discharge |
90% |
| Compatible Inverters |
Fox ESS H1, KH, H3, H3-Pro, US series (1ph & 3ph) |
| Communication & Display |
| Communication |
CAN |
| Display |
LED x 5 |
| Scalability |
Max. 4 units in parallel (up to 8 with H3 Pro) |
| Operating Conditions |
| Installation Location |
Outdoor / Indoor |
| Operating Temperature (Charge) |
-25°C to 55°C (heating function) |
| Operating Temperature (Discharge) |
-25°C to 55°C (heating function) |
| Storage Temperature |
0°C to 35°C |
| Cooling Method |
Natural Convection |
| Humidity |
5% – 95%, no condensing |
| Max. Altitude |
3,000 m |
| Mechanical |
| Dimensions (W x H x D) |
380 x 625 x 147 mm |
| Weight |
50.5 ± 2 kg |
| Ingress Protection |
IP65 |
| Certification |
| Safety |
IEC 62619 |
| EMC |
EN IEC 61000-6-1/3 |
| Transportation |
UN38.3 |
Please Note
*Max. charge/discharge current is affected by cell temperature, cell voltage and state of charge (SoC), per Fox ESS datasheet V1.4.
| System Size |
Units Required |
Junction Box Needed? |
| 5.18 kWh |
1 x EP5-H |
No |
| 10.36 kWh |
2 x EP5-H |
Yes – Fox HV Junction Box |
| 15.54 kWh |
3 x EP5-H |
Yes – Fox HV Junction Box |
| 20.72 kWh |
4 x EP5-H |
Yes – Fox HV Junction Box |
What does the “-H” in EP5-H mean?
The -H suffix denotes the built-in battery warming function. The standard EP5 battery does not include this heating element; the EP5-H is the variant designed for colder or fully outdoor installation locations.
Can the EP5-H be installed outdoors?
Yes. With an IP65 ingress protection rating and a heating element to manage low temperatures, the EP5-H is suitable for outdoor installation, subject to the installer's normal siting and ventilation assessment.
How many EP5-H batteries can I install in one system?
Up to four EP5-H units can be paralleled using the Fox HV Junction Box, for a maximum of 20.72kWh. When paired with the Fox H3 Pro hybrid inverter, up to eight units can be installed.
Do I need a junction box for a single EP5-H battery?
No. A single EP5-H unit connects directly to a compatible Fox ESS inverter. The Fox HV Junction Box is only required when installing two or more EP5-H (or compatible EP-series) batteries in parallel.
Can the EP5-H be mixed with the standard EP5 in the same system?
Yes, EP5 and EP5-H units can be paralleled together. However, doing so disables the self-heating function across the whole stack, so this configuration is not recommended for cold-climate or unheated outdoor installations.
What warranty does the EP5-H carry?
The EP5-H carries a 10-year warranty, comprising 5 years as standard plus a further 5-year extension upon product registration with Fox ESS.
