Fox ESS announced the launch of the EPS Box SP on 18 July 2025. The company describes it as a dedicated backup switching device for its single-phase hybrid systems, available to order through its distribution partners1.
The device sits between the grid, the inverter and the household circuits, and switches the home to backup power automatically when the grid fails1. Fox ESS says it is designed to support whole-home backup rather than a limited set of essential loads, keeping all appliances and circuits running during an outage, subject to system sizing and installer configuration1. It is compatible with the company's existing single-phase hybrid inverter range and supports what Fox ESS calls the latest firmware enhancements for smart switching1.
The company positions the product against third-party automatic transfer switch (ATS) systems, which it says carry cost and complexity. The EPS Box SP requires no third-party switchgear, according to the announcement1. Fox ESS lists fast automatic switching, a compact installer-friendly design and optimisation for its own single-phase hybrid systems among the benefits1. It also integrates with the Fox ESS app, which the company says allows users to monitor system status, set charge schedules and view backup performance in real time1.
"At Fox ESS, we're proud to launch the new EPS Box SP, a compact, cost-effective solution that delivers true whole-home energy resilience"
Fox ESS did not publish a price, a power rating, a switching time in milliseconds or a list of compatible inverter models in the announcement1. Two readers commenting on the launch page asked about fitting the device to existing systems: one asked how to get an EPS Box SP fitted to an existing Fox hybrid inverter, and another asked whether it is compatible with the H1 Gen1 inverter, specifically an H1-5.0-E1. No reply from Fox ESS to either question appears on the page1.
Why it matters for households
Backup capability is the part of a home battery system that determines whether a household keeps power during an outage, and it is often the part that is least clear at the point of purchase. Many hybrid systems supply only a dedicated backup circuit, so a few sockets or a single lighting circuit stay live while the rest of the house goes dark. A gateway that switches the whole consumer unit changes that, but only within the limits of the inverter and battery installed. Fox ESS states the whole-home claim is subject to system sizing and installer configuration, so the size of the inverter and battery, and how the property is wired, decide what actually stays running1. The removal of third-party switchgear matters for cost and for who takes responsibility for the installation, since the switching device and the inverter come from one manufacturer. For a household weighing backup power options, the practical questions are which circuits are covered, how long the battery can carry them, and whether the existing inverter is on the compatible list. Fox ESS has not published that list1. Households with Fox ESS home batteries and hybrid inverters are the intended market, and the company's wider range is covered in its manufacturer pages.
What happens next
The EPS Box SP is available to order through Fox ESS distribution partners as of 18 July 20251. No installation dates, pricing or compatibility schedule beyond the existing single-phase hybrid range has been reported1.