This formula states that the output energy from a battery is just the voltage times the battery's capacity in watt-hours. There is an amount of energy stored in the battery. However, the rate of output would depend on the system its powering.
Since this is a particularly confusing part of measuring batteries, I'm going to discuss it more in detail. Power capacity is how much energy is stored in the battery. This power is often expressed in Watt-hours (the symbol Wh).
Power capacity is how much energy is stored in the battery. This power is often expressed in Watt-hours (the symbol Wh). A Watt-hour is the voltage (V) that the battery provides multiplied by how much current (Amps) the battery can provide for some amount of time (generally in hours). Voltage * Amps * hours = Wh.
If you have a 10 kWh battery with an output of 5 kW, then installing another one of those batteries would double your battery's capacity and output. Combined, you'd have 20 kWh of energy storage capacity and 10 kW of power output. Your installer is your greatest asset in figuring out how much power you need.
Battery power and capacity are scalable. The more batteries you have, the more power your battery can handle, and the more energy you'll be able to store. If you have a 10 kWh battery with an output of 5 kW, then installing another one of those batteries would double your battery's capacity and output.
We found the average power output of most home batteries to be between 5 kW and 9 kW, based on the home batteries we've reviewed. But there are outliers, and it's definitely possible to find batteries with power outputs above 9 kW.