Fox ESS
H3 Hybrid Inverter + ECS2900
Popular hybrid inverter and battery stack with strong installer support.
From £4,800 installed
How it scores
Scores based on published manufacturer specifications and weighted criteria — not lab testing. Methodology.
Specifications
- Weight kg
- 52
- Usable kWh
- 10
- Dimensions mm
- 600x240x830
- Warranty years
- 10
- Ac or dc coupled
- DC
- Inverter built in
- Yes
- Round trip eff %
- 95.5
- Cycle count warranty
- 6000
- Depth of discharge %
- 100
What I noticed
Fox ESS has become one of the most commonly quoted battery systems in the UK installer market over the past two years. The H3 hybrid inverter paired with the ECS2900 battery stack is the typical configuration — 10kWh usable, DC-coupled, 95.5% round-trip efficiency. The system is modular, meaning you can add another ECS2900 battery unit later to reach 20kWh without replacing the inverter.
The 6,000-cycle warranty is one of the stronger claims in this comparison and implies a 20+ year operational life at one full cycle per day. At £4,800 for a 10kWh install, it is competitive with the GivEnergy AiO on cost while offering slightly more storage capacity.
Who it suits
Households wanting a cost-effective DC-coupled hybrid system with room to expand. If you are starting with solar and battery and think you might want more storage in future — an EV, a heat pump, a second phase of panels — the modular Fox ESS architecture makes scaling straightforward. The wide installer base in the UK means competitive quotes are available in most areas.
What I'd watch for
Fox ESS is a Chinese manufacturer with a shorter UK track record than some European competitors. The hardware quality is generally good, but long-term parts availability and UK warranty service — particularly for the inverter — is worth checking with your installer. Some installers report that Fox ESS's UK support has improved significantly in the past 18 months; others have had slower experiences. Get a clear picture of how your installer handles warranty claims before committing. The monitoring app is functional but not as polished as the GivEnergy or Tesla platforms.