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Fox ESS EP5 Battery 5.18kWh

Battery Storage

Fox ESS EP5 Battery 5.18kWh

Stackable 5.18kWh LiFePO4 module for Fox ESS hybrid inverters. UK-popular mid-tier choice.

7.8
Great

£1235.00 ex VAT

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How it scores

Usable Capacity(25%)
6.5/10
Round-Trip Efficiency(25%)
8.5/10
Inverter Compatibility(20%)
7.5/10
Warranty & Cycle Life(20%)
8.8/10
Value for Money(10%)
8.3/10

Scores based on published manufacturer specifications and weighted criteria — not lab testing. Methodology.

Specifications

Chemistry
LiFePO4
Weight kg
50
Usable kWh
4.92
Warranty years
10
Ac or dc coupled
DC
Inverter built in
No
Round trip eff %
95
Depth of discharge %
95

What I noticed

Fox ESS has become one of the most-installed hybrid inverter brands in the UK in the last two years, and the EP5 is their current 5.18kWh stackable LiFePO4 battery module. Pair with a Fox ESS H series or EP series hybrid inverter for an integrated system.

The EP5 uses LiFePO4 prismatic cells with passive cell balancing and an integrated battery management system. Stack up to 5 modules per Fox inverter for 25kWh total capacity. The 10-year warranty matches the inverter warranty for a coordinated system warranty.

Who it suits

Installs already running or planning a Fox ESS hybrid inverter — the integration is mature, well-supported by UK installers, and the Fox cloud monitoring is solid. Also a strong cost-per-kWh option in the mid tier.

What I'd watch for

Best paired with Fox ESS inverters — third-party compatibility is limited. Fox ESS warranty support quality varies by installer — choose an installer with established Fox accreditation. The EP5 is the residential variant; commercial-scale installs use the EP11.

EP5 Battery 5.18kWh head-to-heads

Side-by-side scoring vs each alternative in our shortlist.

vs

Sunsynk L5.3 5.32kWh IP65

Compare specs, scores, and verdict.

vs

Alpha ESS Smile G3 10.1kWh All-in-One IP65

Compare specs, scores, and verdict.

vs

Enphase IQ Battery 5P 5.0kWh

Compare specs, scores, and verdict.

Other Battery Storage on my shortlist

Sunsynk L5.3 5.32kWh IP65
8.0

Sunsynk L5.3 5.32kWh IP65

IP65 outdoor-rated LiFePO4 module designed to pair with Sunsynk hybrid inverters. 5.32kWh wall-mount.

£1660.00 ex VAT

Alpha ESS Smile G3 10.1kWh All-in-One IP65
8.8

Alpha ESS Smile G3 10.1kWh All-in-One IP65

Korean-engineered AIO storage system. 10.1kWh + hybrid inverter, IP65-rated for outdoor install.

£2001.89 ex VAT

Enphase IQ Battery 5P 5.0kWh
8.5

Enphase IQ Battery 5P 5.0kWh

AC-coupled 5kWh module for Enphase microinverter systems. Plug-and-play, no separate hybrid inverter needed.

£2636.65 ex VAT

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