The short version

Key points

  • The Fox ESS Power Cube combines modular batteries, a hybrid inverter, backup hardware and monitoring in one system.
  • EQ5500 battery modules provide 5.46 kWh each, with systems configured from 10.92 kWh to 49.14 kWh using two to nine modules.
  • The installation uses a 15 kW three-phase inverter and 27.3 kWh of usable battery capacity.
  • The system is designed for whole-home backup, with Fox ESS claiming a changeover time of less than 20 milliseconds.
  • The installation took about four hours, although longer-term performance, savings and backup behaviour were not assessed in this video.

A modular battery system for an existing home

The installation took place at an acreage property in Western Australia with solar that had already been operating for nearly 10 years. The property has an existing switchboard, an older solar inverter and several substantial electrical loads, including a bore pump, pool pump and water pump connected to rainwater tanks.

Rather than using separate battery, inverter and backup enclosures, Fox ESS has designed the Power Cube as a coordinated modular system. The battery, hybrid inverter, backup functionality and monitoring are intended to work together, which can reduce the number of separate components and connections required during installation.

Battery capacity and inverter options

The system uses EQ5500 battery modules, each contributing 5.46 kWh. Fox ESS supports between two and nine modules, giving configurations from 10.92 kWh to 49.14 kWh. The batteries use LFP chemistry and have a stated 100 percent depth of discharge.

The installation featured 27.3 kWh of usable capacity and a 15 kW three-phase inverter. The PQ3 three-phase inverter range includes 5 kW, 10 kW and 15 kW models, while the single-phase version spans 5 kW to 12 kW. The three-phase inverter has three MPPTs with 20 amps per string, according to the video.

The existing solar was configured to work with the new hybrid inverter. This means an older solar installation may not necessarily need to be removed, although the existing system and the battery need to be suitably matched.

Whole-home backup and installation hardware

The Power Cube is designed for whole-home backup. The three-phase system supports a 63 amp bypass, while Fox ESS uses an Airgate unit within the switchboard. This combines the changeover switch, meter, bypass switch and CT monitoring in one compact unit.

Fox ESS states that the changeover can occur in less than 20 milliseconds. The video notes that a battery alone does not guarantee backup during a grid outage, because the inverter, backup hardware and installation configuration all need to support that function.

The retrofit presented several practical challenges, including existing wiring and a gas pipe that required the installers to rework parts of the installation. Despite those complications, commissioning was completed in about four hours, from 12:30 to approximately 4:00.

Protection, controls and monitoring

The EQ5500 battery includes LFP cells, pressure relief, insulation between neighbouring cells, fuses, relays for fault isolation and a DC breaker. The system also includes protections intended to prevent incorrect connections. The Power Cube inverter has AFCI and Type 2 surge protection on both the AC and DC sides, according to the video.

Battery heating is included for cold conditions and can be managed through Fox Cloud. The system also has a built-in touchscreen, allowing installers to check and configure settings at the battery. Basic setup can be completed without an internet connection.

Fox Cloud 2.0 displays solar production, household consumption, battery state of charge and grid imports or exports in an energy flow diagram. The video says the view refreshes every five seconds. The system can also check CT measurement direction and phase during commissioning, run a one-press diagnostic check and support DPP connectivity and dynamic energy programs.

TechManPat’s conclusion

I think the Power Cube has made a strong first impression because it brings the battery, inverter, backup hardware and monitoring into one integrated platform. The installation was clean and surprisingly quick, but I do not yet have the longer-term data needed to judge the savings, solar self-consumption or real-world backup performance. I will assess those points after the system has operated for several months.
Source note

This knowledge-centre summary is based on the linked TechManPat video and reflects the information available when it was published. Check current pricing, availability and policies before acting.