The useful starting point
A solar battery stores energy for later. Its value depends on when you generate, when you use electricity and the alternatives available for any surplus.
Follow a normal day
During daylight, solar generation can supply the home. Surplus may charge a battery, with remaining electricity exported where the connection and tariff allow. Later, the battery can supply some household demand and reduce grid imports.
The order depends on your controls. A tariff may make deliberate grid charging useful; a backup reserve may keep part of the battery unavailable for routine use. Ask the installer to demonstrate normal operation and explain what settings you can change.
Try the interactive energy-day explainer to follow daytime, evening and overnight scenarios.
Understand the units
| Term | What it describes |
|---|---|
| kWp | The rated peak capacity of the solar array under test conditions |
| kWh | An amount of energy, such as annual generation or usable battery storage |
| kW | A rate of power, such as the output a battery inverter can deliver at a moment |
| Round-trip efficiency | The relationship between charging energy and energy delivered back out |
A large battery can still have a modest output limit. Equally, a powerful inverter does not create extra stored energy. Both numbers belong on your comparison sheet.
Choose a design for new or existing solar
In a new system, panel strings, inverter capacity and storage can be designed together. In a retrofit, record the existing inverter model, export arrangement and warranties first. Ask how the proposed battery connects and whether it requires replacement equipment.
“AC-coupled” and “DC-coupled” describe how components connect. Neither label proves one installation will be best for every home. Compatibility, conversion losses, constraints and cost need to be considered together.
Separate bill savings from resilience
A grid-connected battery does not necessarily power the home when the grid fails. Backup needs appropriate isolation, controls and wiring. A design may support selected circuits rather than every load.
If resilience matters, make a list of essential appliances and ask how the installer will verify that the system can run them together. Read our power-cut explanation before paying for a backup option.
Bring evidence to the survey
- Annual electricity demand and, ideally, half-hourly meter data.
- Existing panel and inverter details, if you have solar.
- Any EV, heating or occupancy changes you expect.
- Space available for equipment and possible cable routes.
- The tariff you use and its conditions for import and export.
Use the scenario tool to explore losses and reserve, then compare specific products in the product library. Treat the result as a conversation starter, not an installation design.
Published information supports your research. Your installer should confirm the exact product, suitability, scope and terms for your property.
Suggest a correction ↗Your next useful step
Put the information to work.
Take the questions that matter to your project, explore the numbers and decide what to ask next.
