How solar battery storage works

Updated 26 October 2026 · Birmingham Solar

The daily flow of energy.

Solar can serve the home’s demand as it is generated. A suitable storage system can charge from remaining surplus and later discharge when demand is greater than solar output. The controls decide how energy moves within the equipment’s limits.

Some systems also support grid charging. That is a separate tariff opportunity and should be calculated using the electricity purchased, the charging window and losses.

Three limits to understand.

• Usable capacity: how much energy the battery can hold within its operating limits.
• Power: how quickly it can charge or supply the home.
• Efficiency: the share of energy that can be returned after charging and discharging.

A battery can have energy remaining but still be unable to cover a large simultaneous demand. The grid supplies the difference where the installation remains grid-connected.

Savings are more than stored units.

When solar would otherwise be exported, storing it gives up export income. The benefit is the grid electricity avoided after losses, less the export income forgone. Equipment and installation costs then need to be compared with that extra annual benefit.

For an existing solar system, keep the original solar benefit separate. The additional battery benefit is the difference between the two scenarios, not the total benefit of solar and storage together.

Understand control settings.

Schedules, reserve levels and operating modes change the available storage. A high backup reserve leaves less energy for routine use. Competing schedules in a battery, EV charger and supplier app can also give a different result from the intended plan.

Ask the installer to explain the settings at handover, what you can change, and where to find support. Backup during an outage requires an appropriate system design; it is not an automatic consequence of adding a battery.

Choose a route to storage.

You can discuss a new solar and battery installation, a retrofit to existing panels, or a standalone battery. The most useful starting information is your consumption pattern, tariff, existing equipment and what you want the system to do.