18.08 kWh home battery with backup power, single-phase

Two battery modules of 9.04 kWh under a Sigen Energy Controller of 6 kW, with the Sigen Energy Gateway HomePro SP added for backup power. Together 18.08 kWh, of which almost all is usable: Sigenergy states 100 percent depth of discharge.

We come across this size with households that are away for much of the day and switch everything on at once in the evening. Two modules are enough to get through a winter evening without buying in, and during an outage you immediately have a decent buffer to fall back on.

What the gateway does

The gateway disconnects your installation from the grid the moment the grid drops out, and puts the assigned circuits onto the battery. It supports both the whole home and part of it. The latter is usually the wiser choice, because then you spread 18 kWh over the things that really matter instead of a dishwasher that can wait anyway.

The power is the limit, not the capacity

Eighteen kilowatt-hours sounds like a lot, and it is. But during an outage this system delivers 6 kW continuous, limited by the controller. You can keep going for a long time, just not with everything at once. Count on cooling, lighting, heating and working. Not on cooking, drying and charging at the same time.

When you're better off with something else

If you have three phases at home, you're on the wrong version here. A single-phase controller can't serve the other two phases during an outage, so half your house stays dark regardless. In that case look at the 3-phase version with the HomePro TP.

Installation

The backup power circuits need to be fitted separately, behind the gateway. That costs 500 euros more than a normal battery installation. Choose which circuits those will be in advance, so the installer doesn't have to improvise.