How Does a Solar Battery Work and Benefits of Installing Batteries?
The development of solar energy as a valuable power resource for the residential and commercial market has increased the need for energy storage devices that can save the generated solar energy across the day for later use at night.
By coupling the solar battery with a PV array and a hybrid inverter or charge controller, the PV modules installed in your roof will send the DC electricity to supply the electric loads of your house and use the excess solar energy to charge the batteries. This allows you to maximize the use and value of your generated solar energy
Truly understanding how do solar batteries work can be a complicated task, but we can simplify it for you.
How do Solar Batteries Work?
The storage process of a solar battery is actually very similar to the process of an automotive battery.
Basically, the charge controller sets a specific voltage that is selected according to the battery bank voltage itself. When the PV array generates DC electricity, the controller device adjusts the voltage output and delivers the correspondent electric current to the battery.
This electric current passes through an energy conversion process that goes from electricity to chemical energy during the charging process. Meanwhile, when discharging, the conversion process goes from chemical to electrical energy.
In order to generate these energy conversions, two electrodes from different metal components must be placed inside a conductive media called electrolytic solution. These electrodes represent the positive and negative terminals that will be connected to the controller device and the electrolytic solution is the media through which electrons will pass from one side of the electrode to the other.
Types of Solar Batteries
There are mainly two types of solar batteries in the market. Let’s analyze both of them
- Lead Acid
They consist of two electrodes immersed in a solution of sulfuric acid and water. The positive electrode is made of lead oxide and the negative one of pure lead. An electrically insulating membrane prevents them from colliding with each other when moving the battery.
These batteries need more maintenance and considerations than lithium-ion. However, they are cheaper than lithium.
Here you may find listed the different types and subtypes of lead-acid batteries:
- Flooded Lead Acid (FLA)
- Valve Regulated Lead Acid (VRLA)
- Absorbed Glass Mat (AGM)
- Gel cells
- Lithium-ion (Li-ion)
Safe rechargeable batteries composed of an anode and a cathode that store lithium-ions and are immersed in an electrolyte that carries these from one to the other through a separator. This movement of particles creates free electrons in the anode creating a charge at the positive current collector.
See the figure below to get a more graphic approach to the last explanation.
Fig.1: Lithium-ion batteries charge mechanism.
Why Should I Install Solar Batteries?
There is an intrinsic issue with solar energy which is related to intermittency. Solar radiation patterns change across the day and change according to the season as well. Despite that there are models and data to predict these changes, your solar array may not be able to cover the entire needs of your loads across the entire day, especially in cloudy days.
However, by using a solar battery you will have a backup reserve that will allow you to cover your energy needs across the day.
Moreover, you will be able to shift the excess solar power that your PV array generates during the day to store it inside the battery and use it at night. This will save you money in Time of Use electricity rate tariffs where night rates will be much more expensive than day time rates under which you would be receiving payment for the extra solar energy.
Moreover, the most important benefit of installing a grid-tied with battery backup system is that you will have power under a blackout or power outage scenario to cover critical loads in your installation.