One of the most misunderstood parts of a solar power system is the battery or battery bank. Some solar battery banks use wet cells, while others use sealed or gel cell batteries, and each have different temperature, mounting, and ventilation requirements.

Every battery is designed for a specific type of charge and discharge cycle. Car batteries for instance, have thin plates to keep their weight down and are designed for a heavy discharge lasting a few seconds, followed by a long period of slow re-charge. Solar batteries however have very thick plates and are designed for hours of heavy discharge, followed by a fast recharge in only a few hours of sunlight.

There are a few critical points to watch out for in the maintenance of solar batteries.  Regular overcharging of batteries will eventually evaporate all of the electrolyte even though the battery might be “sealed.” A low electrolyte level can expose the plates which will gradually warp or “grow” in thickness as they oxidize. This can cause an internal short circuit and ignition of the hydrogen gas.

Plate damage can also occur when there is a large buildup of sediment after the upper plate areas become exposed from reduced water levels and begin to “flake” off. Most liquid acid batteries do not vent gasses while discharging. However, near the end of a typical charging cycle, when the battery is almost “full,” the sulfuric acid and water electrolyte will begin to break down into hydrogen and oxygen a very explosive combination.

When ignited by a nearby spark or flame, an “explosion” can result, but this flash lasts only a fraction of a second, which is usually too fast to ignite nearby walls. However, this is still a very explosive reaction, with plastic battery parts becoming acid-covered shrapnel

Always wear eye protection and acid proof gloves when working around batteries, and have lots of water and sodium bi-carbonate (baking soda) nearby. This will neutralize any acid spills from battery refilling and prevent further corrosive damage.

The alternative energy system will most likely require wiring several batteries together to create a battery bank. Since solar batteries are very heavy, there are weight considerations as well as battery gas venting issues to consider.
The battery storage building or room must ideally have a concrete floor that is slightly sloped to a drainage point for the draining of water during washing or hosing down the battery bank as part of the maintenance.