SolarEdge battery

What it does in a day

Solar covers the house first. Surplus charges the battery. Once the battery is full, the rest exports. In the evening the house runs off the battery until it is empty, then falls back to the grid.

On a time-of-use tariff there is a second trick: charge from the grid overnight at the cheap rate, and run the house off that stored cheap energy during the expensive part of the day. That is worth real money in winter, when there is not enough sun to fill the battery.

Why we match it to the inverter

A battery from one manufacturer bolted onto an inverter from another works, but the two systems each hold half the picture and coordinate through an interface neither of them owns. Charge decisions get made on inferred data.

Keeping the battery on the same management system as the array means one meter set, one control loop, one app, and one company responsible when the numbers look wrong.

If something goes wrong

Battery health, cycle count and state of charge are all visible remotely. Degradation is normal and gradual; a fault is not, and it shows up clearly against the trend.

The warranty is stated in years and in throughput, whichever comes first, and covers retained capacity rather than simply whether the unit powers on.

The honest downsides

A battery has the longest payback of anything in a domestic system. If your tariff has a small gap between import and export prices, it may never pay for itself on arithmetic alone.

It takes up wall or floor space, usually in a garage, utility room or plant space, and it needs ventilation.

Capacity fades with cycles. Plan on the warranted retained capacity, not the day-one figure.