Fox ESS EP5 Battery Review UK: Specs, Price & Verdict

Fox ESS has become one of the most-installed hybrid inverter brands in the UK, and the EP5 is its current stackable high-voltage battery module. It rarely gets a standalone review — most coverage treats it as an accessory to the Fox inverter range rather than a battery in its own right. This review works through the official specs, 2026 pricing, warranty terms, and how the EP5 compares to the GivEnergy AIO and Powervault, so you can see where it fits before you brief an installer.

Fox ESS EP5: specs and capacity

The EP5 is a 5.18kWh nominal LiFePO4 (LFP) module designed to stack in parallel for larger systems. Per Fox ESS's own datasheet (version 1.5, November 2025), each unit runs at 192V nominal (174–219V operating range), supports a continuous charge/discharge current of 27A with peak discharge of 65A for 60 seconds, and delivers a battery pack round-trip efficiency of 95% or higher. Depth of discharge is rated at 90%, which the datasheet quotes against the 5.18kWh nominal figure.

• Capacity: 5.18kWh nominal per module, stackable to a maximum of 4 units in parallel — 20.8kWh total
• Chemistry: LiFePO4 (LFP), with an integrated fire protection function
• Dimensions / weight: 380 x 625 x 147mm, 50.5kg ± 2kg per module
• Protection rating: IP65, rated for outdoor or indoor floor/wall mounting
• Operating temperature: 0–55°C charging and -10–55°C discharging as standard; an optional warm-up function extends both to -25–55°C
• Communication: CAN bus, with a simple 5-LED state-of-charge display on the unit itself — no built-in screen

The IP65 rating and wide operating range make the EP5 a reasonable fit for an unheated garage or an outdoor wall, which matters if you're short on indoor space. For a wider look at how capacity and DoD figures translate into real household storage, see our home battery storage guide.

Fox ESS EP5 price in 2026

The EP5 module itself lists at around £1,235 ex VAT for the battery alone, before installation, inverter and any additional modules. Fox ESS doesn't sell direct or publish a fixed retail price, so the figure above reflects current UK distributor listings rather than a guaranteed price — your final installed quote will depend on the installer, the inverter pairing, and whether you're stacking multiple EP5 units. For a fuller sense of how battery-only pricing scales into a complete installed system, our home battery cost guide breaks down typical UK installed price bands by capacity.

Warranty is 5 years as standard, extendable to 10 years for an additional fee — a shorter default term than several rivals in this capacity band, so it's worth pricing the extension in from the outset rather than treating the 5-year figure as the real cost of ownership.

The catch: it only pairs with Fox ESS inverters

The EP5 is DC-coupled and built specifically for Fox ESS hybrid inverters — the H1, KH, H3 and H3-Pro ranges. Unlike an AC-coupled battery that can be retrofitted onto an existing inverter of any brand, the EP5 needs a compatible Fox ESS inverter already in place, or one specified as part of the same install. That makes it a strong, cost-effective choice if you're already committed to (or planning) a Fox ESS system, and a non-starter if you have a GivEnergy, SolarEdge or other brand's inverter you want to keep. Our hybrid inverter buyer guide covers how DC-coupled and AC-coupled batteries differ in practice, and what that means for retrofit versus new-build installs.

Fox ESS EP5 vs GivEnergy AIO

The comparison most homeowners actually reach for is Fox ESS against GivEnergy, and the two sit at opposite ends of the same market. GivEnergy's All in One 13.5kWh bundles a 5kW hybrid inverter and battery into a single AC-coupled unit with a 10-year warranty as standard, at a materially higher price point than a single EP5 module. The EP5's advantage is modularity and a lower entry cost per kWh if you're building up capacity gradually or already own a Fox inverter; GivEnergy's advantage is a longer standard warranty and a simpler one-box AC-coupled install that doesn't lock you into a specific inverter brand. Our full Fox ESS vs GivEnergy comparison goes deeper on where each wins.

Fox ESS EP5 vs Powervault

Powervault's PVCompact range takes a different approach again: it's AC-coupled, bolts onto an existing solar inverter of any brand without touching it, and ships in smaller 4–8kWh usable capacities aimed squarely at retrofit. If your priority is avoiding any change to an existing inverter setup, Powervault is the more flexible option; if you're specifying a new Fox ESS hybrid system from scratch or already run one, the EP5's DC-coupled efficiency and lower unit cost make more sense. See our full Powervault battery review for the complete PVCompact and P4 specs.

Who the Fox ESS EP5 suits

The EP5 is a strong pick if you already have, or are specifying, a Fox ESS hybrid inverter — the integration is mature, well-supported by UK installers, and the per-kWh cost is competitive in the mid-tier market. It's a weaker fit if you want an inverter-agnostic battery you could switch brands around later, or if a 10-year warranty as standard matters more to you than upfront price. For a broader shortlist across brands and capacities, our best home battery storage UK roundup ranks the EP5 alongside GivEnergy, Powervault, Tesla and others by what actually matters for solar households.