Sigenergy SigenStor vs Fox ESS EVO 10
Sigenergy SigenStor stores 5.2–7.8 kWh per unit, expanding to 46.8 kWh. Fox ESS EVO 10 stores 9.73 kWh per unit, expanding to 29.18 kWh. Across the setups we list, continuous power is 4–6 kW for the SigenStor and 5–10 kW for the EVO 10. Warranty: 10 years vs 12 years. Intelligent Octopus Flux: SigenStor is “Not on Octopus's list”; EVO 10 is “Sold by Octopus for this tariff; not on its FAQ list”.
Figures from manufacturer documents, last checked 26 Sept 2026. We don't rank products or take payment for results.
How they're built
Sigenergy SigenStor
Modular: Energy Controller (hybrid inverter, solar on DC side) plus stacked battery modules.
Backup: Sigen Energy Gateway.
Fox ESS EVO 10
All-in-one: battery with built-in hybrid inverter (solar connects on the DC side).
Backup: Built-in EPS (backup) output.
Side by side
| Specification | Sigenergy SigenStor | Fox ESS EVO 10 |
|---|---|---|
| Usable capacity (per unit) | 5.2–7.8 kWhPer module: BAT 5.0 = 5.2 kWh, BAT 8.0 = 7.8 kWhSigenergy datasheet, Specification table | 9.73 kWhcalculatedCalculated; the datasheet gives total energy and depth of discharge, not usable energyFox ESS datasheet, p.2, Battery Connection |
| Battery chemistry | LFP (LiFePO₄)Sigenergy datasheet, Specification table | LFP (LiFePO₄)Fox ESS datasheet, p.2 |
| Maximum usable storage (expanded) | 46.8 kWhcalculatedPer controllerSigenergy datasheet | 29.18 kWhcalculatedCalculated from parallel limit and usable capacityFox ESS datasheet |
| How it expands | 1–6 battery modules per controllerSigenergy datasheet, p.2, Battery connection | Up to 3 EVO units in parallelFox ESS datasheet, p.2, EPS output: Parallel operation |
| Continuous power (per unit) | 3–6 kWSingle-phase controllers 3.0–6.0 kW; also limited by battery modules (2.5 kW per BAT 5.0, 4 kW per BAT 8.0)Sigenergy datasheet, p.2, Single-phase controller, nominal output power | 5–10 kWEVO 10-5-H: 5 kW · EVO 10-8-H: 8 kW · EVO 10-10-H: 10 kWFox ESS datasheet, p.2, AC output rated power |
| Peak power | 4.5–9 kWSingle-phase backup peak for 10 seconds, 4.5–9 kW by controllerSigenergy datasheet, p.2, AC output (backup), peak 10 s | 10–20 kWBackup (EPS) peak for 10 seconds: 10 / 16 / 20 kVA by modelFox ESS datasheet, p.2, EPS output |
| Architecture | Modular: Energy Controller (hybrid inverter, solar on DC side) plus stacked battery modulesSigenergy datasheet, p.1–2 | All-in-one: battery with built-in hybrid inverter (solar connects on the DC side)Fox ESS datasheet, p.1 |
| Max solar input | 6–12 kWSingle-phase controllers 3.0–6.0 SPSigenergy datasheet, p.2, DC input | 16–20 kWMax PV array: 16 kWp (5 kW model), 20 kWp (8 and 10 kW models)Fox ESS datasheet, p.2, PV input |
| Backup switchover time | 0 msNeeds the Sigen Energy Gateway; load-side disruptionSigenergy datasheet, p.2, footnote 1 | 4 msLess than 4 msFox ESS datasheet, p.2, EPS switch time |
| Backup needs | Sigen Energy GatewaySigenergy datasheet, p.2, footnote 1 | Built-in EPS (backup) outputFox ESS datasheet, p.1–2 |
| Indoor / outdoor | Not documented | Indoor and outdoor (IP66)calculatedFox ESS datasheet, p.2 |
| Dimensions | 767 × 270 × 260 (per module)W × H × DSigenergy datasheet | 584 × 1009 × 197W × H × DFox ESS datasheet, p.2 |
| Weight | 55–70 kgPer module: 55 kg (BAT 5.0), 70 kg (BAT 8.0)Sigenergy datasheet | 113 kgFox ESS datasheet, p.2 |
| Warranty (UK) | 10 yearsBattery and Energy Controller; installed on or after 1 June 2023Sigenergy warranty, p.1 | 12 yearsFox ESS warranty, p.2, performance warranty table |
| Capacity guaranteed at end of warranty | 70%70% of usable energySigenergy warranty, p.1 | 70%70% of nominal energyFox ESS warranty, p.2 |
| Warranty conditions | Must stay connected to the internet for the full 10 years; 5 years minimum otherwise.Sigenergy warranty, p.2 | Not documented |
How long each runs your home in a power cut
Every setup we list for both, from a full battery with no solar. Appliance figures are typical estimates; use the calculator below with your own.
| Setup | Usable | Continuous | Essentials (fridge-freezer, lights, Wi-Fi, TV, charging) | Essentials + air-source heat pump (winter) |
|---|---|---|---|---|
| Sigenergy SigenStor · 6.0 SP controller + 1 × BAT 8.0 | 7.8 kWh | 4 kW | 47.5 hours | 4.5 hours |
| Sigenergy SigenStor · 6.0 SP controller + 2 × BAT 8.0 | 15.6 kWh | 6 kW | 3 days 23 hours | 8.9 hours |
| Sigenergy SigenStor · 6.0 SP controller + 3 × BAT 8.0 | 23.4 kWh | 6 kW | 5 days 23 hours | 13.4 hours |
| Fox ESS EVO 10-5-H (5 kW) | 9.73 kWh | 5 kW | 2 days 11 hours | 5.6 hours |
| Fox ESS EVO 10-8-H (8 kW) | 9.73 kWh | 8 kW | 2 days 11 hours | 5.6 hours |
| Fox ESS EVO 10-10-H (10 kW) | 9.73 kWh | 10 kW | 2 days 11 hours | 5.6 hours |
Try your own appliances
Average draw 156 W from 7.41 kWh available.
Everything on at once: 415 W — within the 4 kW limit
- Starts from a full battery with 0% held back as reserve.
- 5% extra allowed for wiring and standby losses on top of the manufacturer's usable figure.
- Appliance figures are typical averages; your own may differ. Enter your own wattage for the most accurate result.
- Assumes no solar recharging during the outage.
- SigenStor: Warranty figures are from Sigenergy's Europe warranty; confirm UK coverage with your installer.
- SigenStor: Round-trip efficiency is not stated as a single figure in the datasheets we hold.
- SigenStor: Larger single-phase controllers may exist in the UK; this page covers the 3.0–6.0 SP range in the datasheet we hold.
- EVO 10: Usable capacity is calculated (10.24 kWh × 95% depth of discharge); Fox ESS does not state a usable figure in this datasheet.
- EVO 10: Round-trip efficiency is not stated; the datasheet gives a 96.4% battery-to-AC figure at full load, which is one direction only.
Questions people ask
Which stores more, Sigenergy SigenStor or Fox ESS EVO 10?
Sigenergy SigenStor has the higher stated maximum. Sigenergy SigenStor: up to 46.8 kWh (per controller). Fox ESS EVO 10: up to 29.18 kWh (calculated from parallel limit and usable capacity). Per unit, Sigenergy SigenStor stores 5.2–7.8 kWh and Fox ESS EVO 10 stores 9.73 kWh.
Which can run more appliances at once?
Across the setups we list, Sigenergy SigenStor delivers 4–6 kW continuously and Fox ESS EVO 10 delivers 5–10 kW. These are the maximums for each setup; installers can set some systems lower. Continuous power limits how many appliances can run at the same time; capacity decides how long they run.
Which has the better warranty?
Sigenergy SigenStor: 10 years, 70% capacity guaranteed at the end. Fox ESS EVO 10: 12 years, 70% capacity guaranteed at the end. Conditions differ, so check the warranty rows in the table above.
Do Sigenergy SigenStor and Fox ESS EVO 10 work with Intelligent Octopus Flux?
Sigenergy SigenStor: Not on Octopus's list. Fox ESS EVO 10: Sold by Octopus for this tariff; not on its FAQ list. Octopus lists the battery brands it can control in its Intelligent Flux FAQ; see our Intelligent Octopus Flux page for details.
Other comparisons
Tesla Powerwall 3 vs Sigenergy SigenStor
Tesla Powerwall 3 vs Fox ESS EVO 10
Sigenergy SigenStor vs Huawei LUNA2000-S1
Fox ESS EVO 10 vs Sunsynk L5.1 with ECCO inverter
Sources
- Sigen Battery 5.0 / 8.0 kWh datasheet — Sigenergy. Retrieved 26 Sept 2026.
- Datasheet – SigenStor Home (Energy Controller) — Sigenergy. Retrieved 26 Sept 2026.
- Factory Limited Warranty for SigenStor (For Europe) — Sigenergy. Retrieved 26 Sept 2026.
- EVO 10 Datasheet (UK) V1.0 — Fox ESS, V1.0. Retrieved 26 Sept 2026.
- Fox ESS Battery Warranty Policy (UK) Version 4.5 — Fox ESS, 4.5. Retrieved 26 Sept 2026.
- Intelligent Octopus Flux: Frequently Asked Questions — Octopus Energy. Retrieved 26 Sept 2026.
Spotted an error? See how we check data. Always confirm your final design with an MCS-certified installer.