There are a number of different batteries used for home energy storage, and each battery has its pros and cons. Below are some of the more popular batteries for solar energy storage at home.
Lithium-Ion: This is a newer technology and is currently used in many home energy storage systems. Tesla’s Powerwall, for instance, is a lithium-ion battery. Lithium-ion batteries are smaller and lighter than lead-acid batteries and boast a higher depth of charge and a longer lifespan. They also have a higher energy density and can use more of the energy stored (Some of the latest lithium-ion batteries developed can be released to up to 95%, compared to an average of about 50% in lead-acid batteries.)
However, lithium-ion batteries are more sensitive to high temperatures than other batteries, thus more prone to degradation. They are also currently more expensive than many of their counterparts. Yet as research on this technology continues, and the popularity of solar storage increases, you can expect these issues to be addressed and corrected.
Lead Acid: These were the first rechargeable batteries to be invented and can provide energy for long periods of time. They are well-tested and have been used in off-the-grid systems for decades. They are also one of the least expensive batteries on the market.
On the other hand, they are heavy, have a short lifespan and a lower depth of discharge than other batteries.
Nickel-Cadmium: This is another battery that has been used for some time. While nickel-cadmium batteries have a higher energy density than lead-acid batteries allowing for more energy storage and a longer lifespan, they still do not have the highest efficiency on the market and they contain cadmium, a toxic and corrosive chemical that is expensive to safely recycle.
Saltwater: This is another new technology and doesn’t contain heavy metals, instead of using saltwater electrolytes making a saltwater battery easily recyclable. Because these are new they are relatively untested and the only company producing them filed for bankruptcy in 2017. Perhaps we will see more developments here in the future.