It is important that to fully charged the battery for solar panel frequently – at least monthly – otherwise battery may get permanently damaged.
A battery can be fully charged if the average energy consumption of all loads are less as the average charging energy. The batteries store a large amount of energy, under no circumstances you should short circuit the battery. A slow acting type of fuse is recommended at the terminal of the battery.
Batteries can produce flammable gases avoid making sparks or fire around the battery. Make sure that battery room is ventilated. Avoid touching or short circuit wires and terminals. Use isolated tools, stand on dry ground and keep your hands dry.