Solar batteries are common to both commercial and residential solar power systems. A solar battery bank makes solar power available 24 hours a day, regardless of daylight and weather. Selecting the right size, type, and number of batteries needed is important to insure your power system performs properly and to maximize the life of the batteries.
Different Types of Solar Batteries
There are two basic types of batteries that are available for use in a standard solar energy production system: sealed batteries (also called AGM or Gel cell) and flooded lead acid (or FLA) batteries. Sealed batteries require little maintenance to keep them working properly, but FLA batteries tend to have a longer lifespan.
Like most other types of battery, a solar battery operates with direct current. This means that a solar inverter is required to convert direct current into alternating current.
Deep Cycle Solar Batteries
A cycle in a solar battery occurs when it is discharged and then recharged back to its original level. The amount a solar battery is discharged is called the depth of discharge.
Solar Batteries. Source: NREL USA
Deep cycle solar batteries are designed to be repeatedly discharged and recharged in cycles where up to 80% of the solar battery capacity is used up. Deep cycle solar batteries are, therefore, well-suited for solar electric systems. A shallow cycle is when the top 20% or less of the solar battery is discharged and recharged. Shallow cycle batteries are designed to give out lots of power over a short period of time. They are used in vehicles and less suited for solar electric systems.
Solar Charge Controller
Overcharging a solar battery raises its temperature and can damage the battery plates or cause gassing. A solar charge controller limits the charging current when the battery voltage rises.
Number of Solar Batteries for A PV System
The number of solar batteries in your solar battery bank depends on several factors such as the number of solar panels, the number of days the solar batteries run without charging, and the level of discharge before re-cycling. It is better to have several solar batteries in a solar battery bank so as to have more reserve power available and to keep the level of discharge low.
If you’re unsure of what kind of solar batteries will be required, we highly recommend that you consult with a local expert in the field to save time, effort, and money.