If you want to use as much of your ‘free’ generated electricity as possible, a solar battery can help by storing any unused energy until you need it. The downside is that batteries can be costly—up to £6,000 depending on capacity and composition. Add to that their 15-year life span, half that of a solar panel, and they can work out very expensive. With additional annual savings from a solar battery in the region of £200, they may not be the right choice for you.