27.12 kWh home battery with backup power, 3-phase

Three battery modules of 9.04 kWh under a Sigen Energy Controller of 8 kW, with the 3-phase Power Sensor and the Sigen Energy Gateway HomePro TP.

From three modules onwards the question changes. No longer whether you can bridge an outage of a few hours, but how many days you can keep going. With 27.12 kWh and a roof that still generates something in winter, you get a long way during an extended outage, provided you choose sensibly what sits behind the gateway.

The numbers

Storage 27.12 kWh, power 8 kW charging and discharging, C-rate 0.29. The battery can deliver more than the controller lets through. That's not a design flaw but a choice: here you're buying runtime, not peak power. The gateway switches 30 kW and is therefore never the limiting factor.

How long it lasts

A household that falls back on the essentials during an outage, so cooling, heating, lighting and communication, usually sits around 4 to 6 kWh per day. Work out for yourself what that means with 27 kWh in the cupboard. We won't guarantee a figure, because it depends entirely on what you leave running.

What to watch for

Three modules plus the controller plus the gateway is a substantial installation. The battery tower stands on the floor and needs a solid surface. The gateway hangs separately on the wall, close to the meter cupboard. Have the installer look at both spots beforehand, because they're usually not in the same room.

Installation

The backup power work costs 500 euros on top of the normal installation package.