- Rule of Thumb: The inverter's rated power (kW) should align with the battery's capacity (kWh). - Oversizing the battery can lead to underutilization, while undersizing may limit performance. Internal Link Suggestion: Learn. An inverter is the heart of any solar and storage system, converting the direct current (DC) power from your batteries into alternating current (AC) to power your property. Formula: Battery Capacity (Ah) = (Inverter Power × Runtime) ÷ (Voltage × Efficiency). Always use batteries rated for. Pairing a right size capacity battery for an inverter can be a bit confusing for most the beginners So I have made it easy for you, use the calculator below to calculate the battery size for 200 watt, 300 watt, 500 watt, 1000 watt, 2000 watt, 3000 watt, 5000-watt inverter Failed to calculate field.