Lithium-ion solar batteries are a newer form of battery storage technology and are the best solar energy storage system for everyday residential use because they take up little space while still storing a substantial amount of energy. Also, their high Do (depth of discharge) means you can use more energy stored. The battery will last longer, so it won’t need to be replaced as often as a lead acid battery. Plus, their higher efficiency means that you get to use more of the energy your solar panels produce and store – giving you more bang for your buck.