Note: Solar Choice is not affiliated with Fox ESS or any other battery manufacturer. Our reviews are independently written using technical documentation and industry analysis.
At a Glance: Fox ESS Batteries score 1.9 out of 5
Scoring is based on our solar battery scorecard, which is consistently applied to each brand and battery available on the Australian market. This scoring reflects Fox ESS’s residential battery systems including the ECS and HV2600 series.
$ Price: Based on data from Solar Choice’s network of solar installers, the average price for an installed Fox ESS battery is $832 per usable kWh. This makes it one of the lowest-cost options available.
- Company Backing and Trustworthiness (1 out of 5): Fox ESS entered the Australian market around 2021. The company has no dedicated Australian office, which limits its support network and long-term service visibility.
- Warranty Offer (2.5 out of 5): Fox ESS batteries come with a throughput warranty of 4.1MWh per usable kWh, a 10-year product warranty, and a minimum capacity rating of 70% at the end of the warranty period. While these top line figures compare well the score is impacted by some problematic warranty clauses.
- Customer Reviews (2 out of 5): Based on verified customer reviews, Fox ESS holds an average rating of 3.7 from 3 reviews on Solar Choice’s independent platform. This mixed feedback results in a below-average score.
- Functionality (2 out of 5): Fox ESS batteries are IP65 rated for outdoor use and support modular stacking. However, they lack AC coupling, built-in fire suppression, and independent module-level balancing, meaning new batteries may be impacted by older ones in an expanded system. These limitations reduce long-term flexibility and safety features.
Please note that this score and review reflects our opinion only and we encourage readers to do their own research.
Overview of Fox ESS – Company History
Fox ESS is a Chinese energy technology manufacturer specialising in solar inverters, energy storage systems, and EV charging solutions. The company is a subsidiary of Tsingshan Group, one of the largest stainless steel manufacturers globally, which has helped Fox ESS scale its operations across Asia, Europe, and Oceania.
Fox ESS first launched in Australia in 2020, initially selling their solar inverter products. Their first battery was approved by the Clean Energy Council in 2022, meaning they are a relatively new-entrant to the solar and battery market. Fox ESS still do not have any Australian office listed on their website or documentation.
Fox ESS Battery Range and Options
Fox ESS provides a range of high-voltage, stackable lithium iron phosphate (LiFePO4) battery systems under the ECS and EP series which are both approved by the Clean Energy Council. These batteries are typically designed to integrate with Fox hybrid inverters, although some limited compatibility with third-party systems exists.
ECS Series (DC-Coupled, Stackable System)
The ECS series is Fox’s main high-voltage modular battery platform. Each system consists of a CM (control module) and between 1–6 CS (battery modules), supporting capacities from around 5.8kWh up to around 42kWh (nominal).
- Popular ECS models include: ECS2900 (2.6kWh usable), ECS4300H (3.7kWh usable), ECS4800 (4.2kWh usable)
- DC-Coupled: Must be paired with a compatible Fox ESS hybrid inverter
- Depth of discharge: 90%
- Ingress protection: IP65, suitable for indoor/outdoor installations
- Cooling: Natural convection (fan-free)
Expansion is possible, but the warranty requires new modules to be within 0.5V of existing modules and recharged within the past 5 months, making post-installation upgrades technically feasible but logistically complex.
The batteries must be paired with a compatible Fox-ESS inverter and important to note that the maximum inverter capacity for single phase systems is 6kW which will limit the ability for bigger batteries to be discharged or charged quickly.
EP Series (DC-coupled, Fixed Units)
The EP series includes fixed-capacity wall-mounted batteries that combine battery modules and the battery management system (BMS) in a single enclosure.
- Key models: EP5 (5.18kWh), EP11 (10.36kWh) usable capacity
- DC-coupled: Must be paired with a compatible Fox ESS hybrid inverter
- DOD: 90%
- Operating range: -10°C to +55°C
The EP series may appeal to installers seeking simpler, space-saving systems. The EP Series is expandable by adding additional units in parallel. This is a most costly and space-consuming approach than the stackable ECS series.
The EP Series is also limited by Fox ESS hybrid inverter’s which have 6kW as their largest hybrid inverter size.
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How Much Does a Fox ESS Battery Cost?
Fox ESS batteries are among the most affordable on the Australian market. Based on data from Solar Choice’s installer network, the average installed cost is $832 per usable kWh, excluding rebates.
For example:
- A 10.4kWh EP11 system may cost $8,650–$9,200 installed
- A 17.3kWh ECS2900-H6 stack might cost $14,000–$15,500 installed
As Fox ESS batteries are DC-coupled, homeowners would also need to buy a compatible Fox ESS hybrid inverter to connect the system. Fox ESS batteries are most likely to be used when installing solar and batteries for the first time to avoid duplicating the inverter.
Fox ESS systems are eligible for the federal battery rebate, which could reduce the net cost by up to 30%, depending on your state and VPP eligibility.
Fox ESS’s Warranty Offer For Australian Customers
Fox ESS offers a 10-year product and performance warranty for its ECS and EP series batteries. The performance warranty guarantees that the battery will have a minimum of 70% of its original usable capacity after 10 years, or will have throughput a minimum amount as laid out in the below table:
| Product | Nominal Energy (kWh) | Usable Energy (kWh) | Minimum Throughput (MWh) | Throughput per usable kWh |
|---|---|---|---|---|
| EP5 | 5.2 | 4.7 | 19.2 | 4.1 MWh |
| EP11 | 10.4 | 9.3 | 38.4 | 4.1 MWh |
| ECS2900 (4 x battery modules) | 11.5 | 10.4 | 48.6 | 4.7 MWh |
| EQ4800 (4 x battery modules) | 18.6 | 16.8 | 78.6 | 4.7 MWh |
Fox ESS warranty has a problematic condition:
Annual inspection is required from the 6th year after battery’s commissioning date by a Fox ESS authorized suitably qualified technician, and that documented evidence of the inspection is kept on record.
It is very unlikely that any customer will actually follow through with this onerous and costly requirement and this may be a way in which Fox ESS can escape their warranty obligations as their battery fleet matures.
Fox ESS also have no registered office in Australia, so there may be limited support for customers experiencing technical difficulties or going through a warranty claim.
See attached full warranty policy for Fox ESS batteries.
Fox ESS Battery Technical Specifications Table
| Feature | ECS2900-H6 (17.3kWh) | EP11 (10.4kWh) |
|---|---|---|
| Battery Chemistry | LiFePO4 | LiFePO4 |
| Usable Capacity (kWh) | 17.28 | 10.36 |
| Scalability | Modular (up to 29kWh) | Fixed |
| Depth of Discharge (DOD) | 90% | 90% |
| Max Discharge Power (kW) | 5.0 (per system) | 5.0 |
| Round Trip Efficiency | >95% | >95% |
| IP Rating | IP65 | IP65 |
| Cooling Method | Natural Convection | Natural Convection |
| Installation | Stackable, floor mounted | Wall-mounted |
| Minimum Throughput | 4.7MWh per usable kWh | 4.1MWh per usable kWh |
| Operating Temperature (°C) | -10 to 55°C | -10 to 55°C |
Pros and Cons of Fox ESS Batteries
| Pros | Cons |
| ✓ Competitive installed pricing (<$850/kWh installed) | ✗ Limited public performance data or long-term Australian track record |
| ✓ IP65 rated for outdoor/sheltered installs | ✗ Expansion requires SOC and voltage matching — not truly plug-and-play |
| ✓ Modular design for ECS makes it flexible | ✗ Must use Fox inverters — limited third-party compatibility |
| ✗ Annual inspections from year 6 to maintain warranty |
Conclusion: Our Verdict On Fox ESS Batteries
Fox ESS as a new entrant to the market have an aggressive pricing strategy which they hope to win market share. Their batteries are scalable up to over 40kWh however they are limited to a 6kW inverter capacity for single-phase installations.
The warranty terms on face value look competitive or better than some of the bigger brands. However the warranty requirement to get annual inspections and the lack of local presence and support might be an issue for customers experiencing technical problems.
With the short company history, the longevity and reliability of the Fox ESS batteries largely remains to be seen.
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