Deep-cycle, lead-acid batteries are a popular choice for renewable energy applications due to their ability to withstand the demands of solar energy use such as unstable grid energy, heavy cycling (charging and discharging) and irregular full recharging. As far as deep-cycle lead-acid batteries in solar, flooded and valve regulated options are the most viable for storage. Both have pros and cons depending on your site’s environment and application. One valve regulated option—absorbed glass mat (AGM)—is especially advantageous as it is maintenance free, while flooded batteries require watering. Since solar applications can be in hard-to-reach areas, the ability to plug in the batteries and let them function without maintenance is a huge benefit. AGM batteries recombine the hydrogen and oxygen produced during recharge which forms water. This recombination makes the AGM battery maintenance free so you don’t have to worry about watering, acid leaks or corrosion.
Many AGM batteries, however, are primarily designed for dual-purpose or standby applications like emergency backup, and not deep cycling. But Trojan has recently introduced the Reliant AGM with C-Max Technology line. The manufacturer said the line is specifically designed for deep cycling applications through its paste formula, its durable polymer case that provides higher battery cell compression, and a flame arrestor for each cell for maximum safety. The batteries also have a thick separator which ensures high compression for effective contact with the glass mat and plates. This protects against stratification—a condition in which lead sulfate builds on the plates, which eventually reduces storage capacity and battery life. The batteries are manufactured in the U.S. at Trojan’s newest production facility in Sandersville, Georgia.
Battery sizing is also an essential part of the equation, which is often overlooked by users and installers, said Vicki Hall of Trojan Battery. “The single biggest problem in battery underperformance is miscalculated load,” she said. “Batteries in PV systems are routinely undersized due to cost or because the system loads were underestimated. A homeowner adds another TV, and suddenly they don’t have enough power. It’s important to know the customer’s power needs and correctly plan for it.
Trojan offers an online battery sizing calculator, which you can find on the company’s website, to make determining battery capacity for load requirements easy.
“Solutions for solar battery storage are there,” Hall said. “It’s just a matter of knowing how much energy you need and choosing a battery big enough to handle it.”
Daniel Ryan says
Personally, I’ve been building all of my small solar setups over the last five years using UPG brand sealed lead acid AGM batteries off Amazon. They are available in just about every standard battery size and capacity, from at least about 6Ah up to 110. I’m usually building battery banks for my campers out of their 100Ah size (UB12100). I’ve had excellent performance and reliability out of them, and the cost per Ah of capacity is only a little above the golf cart batteries (which are the cheapest good performing deep cycle, but usually only available in a single size, and not AGM).
Thank you for the simple, but informative article. Mine was delivered without instructions and I was just about to send it back. I look forward to installing it this weekend thanks to your assistance.
james william says
Good read. My charger has 2 battery type selections. 1-AGM & WET 2- GEL. I didn‘t know mine was a AGM it ended up being charged as a GEL. Now charger just reads fault and battery is at 7.8 volts
Have I killed it?
Miro Muzik says
We are planning to install a solar panel at our camp in woods of Adirondacks. But during power interruptions which are some time frequent, we would like to have storage capacity for the solar panels, instead of a Propane driven generator.
We would not like the Acid type batteries.
Is there new technology for Lithium or other system batteries available on the market?