4.5 kWh Home Battery with Backup Power, Three-Phase

One AlphaESS SMILE-G3-T10 inverter of 10 kW, one battery module of 4.5 kWh and the Backup-Box PLUS. The latter is the switch cabinet that moves your installation onto the battery when the grid goes down.

Small system, full backup power. That sounds odd, and it is a deliberate choice: the Backup-Box costs here almost as much as the battery itself. People who buy this combination do so because the outage is the problem, not the energy bill.

What 4.5 kWh means during an outage

The module delivers 4.8 kW and carries 4.5 kWh on board. With only a fridge, a freezer, lighting and some electronics running, you sit around 200 to 400 watts and get through a night on this. Switch on the oven and it is empty within the hour. The cabinet switches back cleanly the moment the grid returns.

The Backup-Box belongs indoors

Important to know beforehand: the Backup-Box PLUS is IP21. It may only be mounted indoors, in a dry space. The battery module itself is IP65 and can go outdoors. With an outdoor battery setup, the cabinet still has to go in the meter cupboard or the garage, with cabling in between.

What is inside the cabinet

Ten kilowatts across three phases, a bypass switch and a display. With that bypass the installer can bridge the system without cutting power to your whole installation, which helps during maintenance.

When you are better off expanding

One module of 4.5 kWh under a 10 kW inverter is on the tight side. The inverter can handle far more than the battery delivers. If you already know you want more, the 9 kWh backup power package is a more logical starting point: the same inverter, the same cabinet, twice the storage.

Installation

Backup power needs separate circuits routed past the cabinet. That costs €500 more than a standard battery installation.