Solar Power Battery
A Solar Power Battery stores electrical energy in the form of chemical energy. When the battery is providing electricity, it is created by the chemical reaction occurring inside the battery itself that is generating the electricity. The materials used inside of the solar power battery have a specific natural electrical potential that is used to produce or store energy for use later.
There are two types of batteries: primary and secondary. Primary are your typical battery used in most electrical devices that cannot be recharged. Secondary batteries on the other hand can be recharged, and those are the type we will be discussing here.
A single electrochemical unit with in a battery is called a cell, and thus a solar power battery is made up of several of these cells. A battery bank is made up of one or more batteries.
A solar power battery’s capacity is rated in amp-hours (Ah). Say you have a 100 Ah battery. It will be able to supply 10 amps for 10 hours.
There are several types of rechargeable batteries out there, but we will only be talking about Lead-Acid Batteries because they are the most effective for use in a Home Solar Power Systems.
Deep Discharge Battiers
Home solar power systems use deep discharge batteries. These are different than the starting batteries used to start an engine like your car. The reason you want a deep discharge battery vice a starting a battery is that you need a battery that will supply a low current for a long period of time (to power your household appliances). Make sure you are getting a deep discharge battery and not a starting battery.
Lead-Acid Batteries are the exact same type of battery that are used in your car. All Lead-Acid Batteries depend on the same chemical reaction to generate electricity, however the internal construction varies between batteries.
Flooded Cell Lead-Acid Batteries
These batteries are characterized by the liquid sulfuric acid solution the cells are immersed in. They are the lowest cost battery, but require the most maintenance. Something to note about these batteries is that they have a vented cap which allows hydrogen and oxygen gasses that result from the electrolysis of water during charging to escape the casing. These are potentially hazardous gasses.
There are caps which will recombine the gasses into water mitigating the gasses escaping from the battery though. As a result of this gassing, water is lost during charging requiring the addition of water from time to time. Regardless these are the battery of choice for most home solar power systems because of their low cost and ability to withstand the abuse of continual use.
Valve Regulated Lead-Acid Batteries
Valve Regulated Lead-Acid Batteries (VRLA) batteries differ from Flooded Cell Lead-Acid Batteries in that they prevent the hydrogen and oxygen gases from escaping. VRLA use a pressure valve that forces the gasses to re-form into water vice escaping into the atmosphere. In the event of an overcharge though these vents will open. The benefit to this is that you don’t have to replenish the battery with water, which thus makes these batteries maintenance free.
Absorbent Glass Mat Lead-Acid Batteries
Absorbent Glass Mat(AGM) batteries are a kind of VRLA battery. However the acidic solution is held in a fiberglass mat between the plates allowing them to resist shock and vibration better, but more expensive. They also have a higher energy per unit weight and a higher charge/discharge rate. AGM’s are considered maintenance free as well.
Gel Cell Lead-Acid Battery
Gel Cell Batteries are another kind of VRLA batter. These batteries contain the acid in a gel making them also more shock and vibration resistant that your standard Flooded Cell Lead-Acid Battery, but more expensive. These too are considered maintenance free.