There are three primary categories of batteries used to store energy from photovoltaic (PV) systems – primary, secondary, and tertiary. A secondary battery is a type of maintenance-free sealed lead acid battery that has two electrodes: a positive electrode, called the anode, and a negative electrode, called the cathode. Solar batteries come in different shapes and sizes depending on the size of your system and your needs. Some models are meant for use with a solar charge controller to regularly top off your battery to keep it at full capacity. Other models are designed for use without such an accessory and will discharge over time until they need to be charged again. The specific design of your system will also have an impact on which type of solar battery you should use.

Types of solar batteries

Secondary batteries are generally used to store excess energy generated by PV systems into a battery that can be used later. They are typically maintenance-free and can last for up to five years with proper care.
Primary batteries, on the other hand, are intended for use with solar charge controllers and are not meant to be discharged down to less than 80 percent of their capacity before being recharged. This may include lithium-ion or nickel-metal-hydride models. Primary batteries also have the capability of being charged fully in as little as two hours, which is ideal for those who don’t have time for a lengthy charging process.
Tertiary solar batteries are designed for quick charging but may only be able to charge your system at 50 percent capacity until they need more energy from their primary battery or the sun. These types of solar batteries may also take up a lot of room and may require an inverter if they aren’t connected directly to your system’s charge controller.

Lead acid batteries

A lead acid battery is a type of secondary battery. A lead acid battery consists of an anode, a cathode, and a positive electrolyte solution. The positive electrode, called the anode, is made from lead and the negative electrode, called the cathode, is made from lead dioxide. Both electrodes are immersed in a saturated sulphuric acid solution. When electricity is applied to the electrodes, oxidation takes place at the negative electrode and reduction takes place at the positive electrode creating electrons and protons respectively. These ions then travel through the electrolyte solution to complete their circuit.
The design of your PV system will have an impact on which type of solar battery you should use. For example, if you’re designing a system with no charge controller or that has just one inverter/charger it would be best to use a deep-cycle battery or batteries designed for such systems so they can withstand repeated discharges and recharge cycles without damage. If you’re designing a system with multiple inverters/chargers it would be best to use a series string rather than individual batteries as they are easier to connect together in series.

Lithium-ion batteries

Lithium-ion batteries are the most efficient storage option for solar power. They provide a small, lightweight battery and can be charged quickly with a solar charge controller.

Nickel based batteries

Nickel-based solar batteries are the most common type of battery in use today. They are designed for use on grid-tie PV systems that need to be charged weekly or monthly. Nickel is the best material for making a battery and nickel-based batteries offer the best performance.

Flow batteries

Flow batteries are used to store energy from the photovoltaic (PV) battery. These types of batteries consist of two tanks that are pumped with electrolyte solution and then connected together through a separator membrane. In this type of battery, the electrodes can be made of any conductive material.
Flow batteries do not have a charge controller and charge output is limited by their design. They generate usable power only when they are recharged through a DC-to-DC converter.

How To Compare Your Solar Storage Options

There are several different potential decisions to be made when choosing an energy storage solution for your application. Here are some of the most common ones, as well as which specifications matter most if they fit your needs:

How Much Does A Home Solar Battery System Cost?

Most battery systems cost between $7,000 and $14,000. The size of your system and the type of battery you choose will factor into the price of your home solar battery system. Solar panels also have an impact on your total costs for a battery system.

How Long Do Solar Batteries Last?

Secondary batteries last the longest, but they also need to be replaced more often than tertiary or primary batteries. Tertiary batteries require less maintenance and are the least expensive of these three types. Primary batteries are designed for use with an auxiliary solar charge controller and will not need a replacement until they can no longer store energy.

1) Solar Battery Terminology
2) Types of Solar Batteries
3) How Long Do Solar Batteries Last?

Is Solar Battery Storage Right For My Home?

Before you invest in solar battery storage, consider the size of your system and how often it will be used. Keep in mind that a PV system can only provide enough electricity to your home when the sun is shining. If your system is not used often, or if it’s too small, it might not generate enough power to keep your home running through the night. If you find that a solar battery is right for you, consult with a solar panel contractor to learn more about what types of batteries are best for your system.