The cost of a solar battery system is dependent on many factors, including the brand of the battery, the batteries chemical composition, storage capacity and it's life cycle. On average, a complete solar storage system can cost anywhere between £3,000 to £9,000 depending on the factors mentioned above. Like any new. The installation cost depends on the size and type of the battery. It is typically more financially wise to set up your solar battery system while installing. A new solar panel system can save you around half of your electricity bill on average and the financial gains to be made are even more impressive with the new Energy Price Cap. A solar battery that gives you more usable capacity, lifespan, DoD, and a longer warranty is going to offer you the best value.