Types of Battery for Solar Energy Systems

Types of batteries and how to choose them in solar energy systems

Batteries or savings are the part in which electricity is stored, as solar energy systems consist of solar panels that generate electricity during the daytime and the batteries store electricity for use at sunset and power outages (grid).

The most common batteries that are used in solar energy systems are two main types:

1- Lead Acid Batteries

For several years ago, this type of battery was the most common source of use. It is known for its high current but low energy density and contains highly toxic and environmentally harmful substances.
It is in three forms:
- Liquid batteries with slots: Distilled water can be added instead of evaporated. 

- Tubular Lead acid batteries: This type is identical to the previous example, with difference that lead plates are tubular in shape for more capacity
- Sealed liquid batteries: not subject to the addition of liquids
Gel batteries: less likely to evaporate due to the type of gel rather than liquid
- AGM batteries of glass nature: they retain electricity with glass plates, suitable for cold and high temperatures.

2- Lithium-Ion lithium batteries

Recently, this type of battery has become the most popular for solar energy systems, as it has a higher voltage range, faster charge response, and lower self-discharge.
It does not require maintenance and has a longer life than other types of batteries, because the number of cycles reaches up to 6000 cycles.

The industry of this type of battery developed and a sub-type was produced called:
- Lithium Iron Phosphate Battery Lithium LifePO4
This battery is similar in specifications to a lithium-ion battery, but it is famous for its longer life and thermal stability, less prone to burning and drying out, as it is considered one of the best and safest options for solar energy systems.

Depth of Discharge (DoD)
Depth of discharge means the usable portion of the battery
The discharge rate for acid batteries is 50%, while it reaches 90% for lithium batteries, which means a higher capacity for use.

Charge Rate
This factor must be considered when choosing a battery, indicating how quickly it is discharged and how quickly it is charged.
It is symbolized by the C sign and is written on the battery. This is the factor by which we divide the battery capacity to produce the appropriate discharge speed, which it is advised not to exceed (except for the lithium battery).

for example:
The 200Ah battery with a rating of C20 means 200/20 medium discharge (within 10 hours) suitable for using the most energy consuming appliances such as refrigerator, air conditioner and medium appliances.
The 200Ah battery is rated C10 meaning 200/10 slow discharge (within 20 hours) suitable for use in light fixtures and appliances

It is best to adhere to these criteria when choosing the capacity of the charger (the best charging speed is equal to the discharge speed).

After reviewing this information, you can now choose the type and characteristics of the battery suitable for your use in your home solar energy system.

Written By Solar Point Energy Co. Team