13.5 kWh Home Battery with Backup Power, Three-Phase

Three modules of 4.5 kWh, a 10 kW SMILE-G3-T10 inverter and the AlphaESS Backup-Box PLUS. Together 13.5 kWh with backup power across three phases.

From three modules you hit the maximum the inverter can deliver: 10 kW. A fourth module adds no more power, only storage. This is the point where the system is in balance.

One day off-grid

Thirteen and a half kilowatt-hours is enough to get an average household through a full day, if you pay a little attention. Fridge, freezer, heating pump, lighting and some appliances combined rarely exceed 6 kWh a day. What you add for cooking and laundry decides the rest.

The Backup-Box in short

Ten kilowatts, three phases, bypass switch and display. The cabinet sits between the grid, the inverter and the circuits that must keep running, and switches over automatically the moment the grid drops out. It is IP21, so mount it indoors. The battery modules themselves are IP65 and can go outdoors.

Where it goes wrong if you are not careful

The biggest misconception about backup power is that the whole house keeps running. That is possible, but then everything has to stay within 10 kW, and that does not work if a charging station and a heat pump are connected. In practice we pick a set of circuits that actually matters and leave the rest outside the backup scope. Make that choice with the installer beforehand, not during the first outage.

Installation

Three modules stack under the inverter. The extra work for the backup circuits costs €500 on top of the normal installation package.