Solar and inverter batteries are used to store solar energy (solar electricity) and discharge power as and when needed. Rechargeable solar batteries are used in off-grid Photophovoltaic systems to store excess electricity. Some solar battery banks use wet cells, while others use sealed or gel cell batteries. Each of these batteries have different temperature, mounting, and ventilation requirements.
CATEGORIES OF SOLAR BATTERIES
SMF (Sealed Maintenance Free) batteries are batteries which do not require topping up due to negligible water loss. It is designed in such a way that it cannot be opened or refilled. These batteries are safe, maintenance free and are suitable for low end applications.
Tubular Batteries have openings at top to add distilled water for maintenance and safe running. These batteries are very rugged and used in Cyclic application. These batteries last longer due to complex design and are suitable for high end applications.
TYPES OF SOLAR AND INVERTER BATTERIES
Lead acid batteries are a tested technology that has been used in off-grid energy systems for decades. While they have a relatively short life and lower DoD than other battery types, they are also one of the least expensive options currently on the market in the home energy storage sector. For homeowners who want to go off the grid and need to install lots of energy storage, lead acid can be a good option. Tubular battery is a type of lead acid battery in which the positive electrode is not a grid, but a comb like lead skeleton that holds the positive material with the help of tubular bags. The structure looks like a series of tubes kept side by side along the length of the electrode, hence the name “tubular”.
Lithium batteries stand apart from other battery chemistries due to their high energy density and low cost per cycle. Lithium batteries are safe, with great thermal stability, high current ratings, long cycle life, and tolerance to abuse. Lithium ion batteries are lighter and more compact than lead acid batteries. They also have a higher DoD and longer lifespan when compared to lead acid batteries. However, lithium ion batteries are more expensive than their lead acid counterparts.
Unlike flooded lead acid and other battery chemistries, Lithium batteries do not vent dangerous gases such as hydrogen and oxygen. There’s also no danger of exposure to caustic electrolytes such as sulfuric acid or potassium hydroxide. In most cases, these batteries can be stored in confined areas without the risk of explosion and a properly designed system should not require active cooling or venting.
A significant advantage of lithium over lead-acid batteries is that they do not suffer from deficit cycling. Essentially, this is when the batteries cannot be fully charged before being discharged again the next day. This is a very big problem with lead-acid batteries and can promote significant plate degradation if repeatedly cycled in this manner. LiFePO4 batteries do not need to be fully charged regularly. In fact, it’s possible to slightly improve overall life expectancy with a slight partial charge instead of a full charge.
A newcomer in the home energy storage industry is the saltwater battery. Unlike other home energy storage options, saltwater batteries don’t contain heavy metals, relying instead on saltwater electrolytes. While batteries that use heavy metals, including lead acid and lithium ion batteries, need to be disposed of with special processes, a saltwater battery can be easily recycled. However, as a new technology, saltwater batteries are relatively untested, and the one company that makes solar batteries for home use (Aquion) filed for bankruptcy in 2017.