How to compare solar batteries
There are many ways to compare solar batteries. Here are a few key metrics to keep in mind:
Capacity & power
A battery’s capacity is the total amount of electricity it can store measured in kilowatt-hours (kWh). A battery’s power tells you the amount of electricity that it can deliver at one point in time measured in kilowatts (kW). It is important to consider both capacity and power when evaluating solar batteries. A battery with high capacity but low power can only provide a small amount of electricity at one time but can store enough energy to keep providing that electricity for long periods of time. On the flip side, a battery with low capacity but high power may be able to power many appliances or your entire home at one time, but potentially only for a few hours due to its low capacity.
Just like solar panels, solar batteries have efficiencies associated with them. A battery’s round-trip efficiency represents how much energy can be used as a percentage of the amount of energy that it took to store it in the first place. Batteries experience efficiency losses during the conversion of energy from storage to usable electricity, typically about 5 percent.
Battery life and warranty
Like cell phone batteries, solar batteries naturally degrade over time and will hold less overall charge the more you use them. Solar battery warranties are usually measured in cycles or years and guarantee the ability to hold a certain level of charge by the end of the specified warranty term.