Adding a solar battery bank to your solar power system can be a great way to get more out of your system and come even closer to achieving energy independence. Before you can do that, however, you’ll need to pick the right type of battery for your bank. There are actually several different types of batteries availability, varying in their price and efficiency. One popular type is the AGM battery. What is an AGM battery, and how well does it perform in a solar battery bank? Keep reading to learn all you need to know.
AGM stands for absorbed glass mat, the key defining characteristic of an AGM battery. Without going into unnecessary detail, it’s worth noting that the absorbed glass mat within an AGM battery allows it to hold more power than other varieties of lead-acid batteries. These batteries release the power they store by breaking apart hydrogen and oxygen molecules; to recharge, they reform the hydrogen and oxygen in their cells.
As mentioned above, AGM batteries are one variety of lead-acid batteries, but they’re set apart by the presence of that absorbed glass mat. In addition to allowing AGM batteries to store more power, the absorbed glass mat also reduces the amount of maintenance the batteries require. AGM batteries are completely sealed, so you never need to check fluid levels or worry about the battery releasing gasses, as you do with flooded lead-acid batteries. This makes them safer as well.
When looking at AGM batteries, you might notice that some of them are marked as “deep-cycle” batteries. What does this mean? The phrase refers to the “depth” at which a battery can safely discharge its power without damaging itself. Nearly all batteries must hold onto a portion of the power they store, or else they can over-discharge and potentially impact their overall energy storage capacity. A deep-cycle battery can discharge a greater percentage of the power it stores than a standard battery.
For example, a standard AGM battery might be able to discharge between 50% and 60% of its stored power. However, an AGM deep-cycle battery can often discharge 80% to 90% of its power. This means that you get more usable power from your battery. So, while a deep-cycle battery might cost more for the same storage capacity, it’s generally worth the added cost, since you get more usable power per battery.