The price of solar batteries depends on their size, and determining the suitable size for your household or business hinges on the following factors: energy usage, budget, size of your solar array, and perhaps the most important —  your purpose for buying a battery.  For large energy needs, the Tesla Powerwall with its 13.5kWh capacity is recommended, or the LG Chem RESU 6.5kWh for moderate energy requirements. If your energy consumption is low, you could get a small battery less than 5kWh to serve your needs.