You can buy a solar storage battery for less than £2,000 or more than £11,000. But if you're looking for a battery with a medium capacity of 5 kWh. Size isn't everything. The price of a solar storage battery is affected by many factors other than capacity. Brand name, for example – as you'll know if. A storage battery cuts your energy bills, shrinks your carbon footprint and can even keep your home running in a power cut. But it costs thousands to buy and install, and may not break even. The bigger your house and the more energy you use, the higher capacity your solar battery will need – and the more you'll need to pay for it. Here's a quick cost calculator to help you plan: By now, you've made up your mind whether or not to include a solar battery with your solar PV system. If you don't already have panels, the next step is to compare quotes for panels.