The primary things to evaluate are the battery’s capacity and power ratings, depth of discharge, round-trip efficiency, warranty and the manufacturer’s reputation. Compare these things to your array size and how much energy you’d like to store.
There are several types of chemical compositions used in home energy storage. Lead acid, lithium ion and saltwater are the big three – with lithium ion most commonly used in solar panel systems. Lithium ion batteries are lighter and smaller than lead acid batteries and their depth of discharge and lifespan are also much longer. However, they do tend to be a bit more expensive than lead acid.
How long a battery lasts depends on the battery you buy, how much capacity it will lose over time and whether it is properly maintained. For example, a battery might be warrantied for 5,000 cycles or 10 years at 70 percent of its original capacity. This means that at the end of the warranty, the battery will have lost no more than 30 percent of its original ability to store energy.
Most people have heard of Tesla Powerwall. In fact, Axium Solar is an authorized dealer and certified installer of the Powerwall. The Sonnen battery is another option. With emerging technologies however, there are quite a few energy storage options on the market today and we can implement your preference.