Typical cost structure in the UK

When does battery storage make financial sense?

Battery storage makes the most sense when solar generation and household demand do not happen at the same time. In many homes, solar production peaks during the day while electricity use rises in the evening. A battery shifts part of that solar energy into the period when the home actually needs it.

• Good fit: evening consumption, regular daytime solar surplus and high import tariffs.
• Weaker fit: very low daytime generation, heavy shading or tiny household loads.
• Best TSUN angle: calculate self-consumption, not just battery size.

Example payback calculation

If a battery helps a household use an additional 220 kWh of solar energy per year, and imported electricity costs around £0.25–£0.30 per kWh, the extra annual saving is roughly £55–£66. If the battery upgrade costs £500, the simple payback on the battery element alone is about 8–9 years.

Simple payback = extra battery cost ÷ annual extra savings

This is only a rough model. Actual results depend on tariff, shading, orientation, export value, battery losses, usage pattern and product lifetime.

Complete set or retrofit battery?

A complete set is usually easier when the customer is starting from zero. A retrofit battery can be more attractive when the existing PV and microinverter setup is relatively new and technically compatible. If compatibility is uncertain, a “cheap” retrofit can become expensive through adapters, rewiring or added metering hardware.