When to use batteries? Batteries are a must if you are going off grid. There is no other way to store electricity. The electricity generated from a solar, wind or hybrid system must be stored in batteries before they can be used effectively.
The only type of battery that you should consider is deep-cycle lead-acid industrial battery. The electrolyte battery technology has been in use for a long time and it has been redesigned and engineered for great performance. It now comes in a "maintenance-free" gel pack design as well.
Deep-cycle lead acid batteries, if properly maintained can last 15-20 years and when its life has expired the batteries can be recycled.
Depth of Charge:
A battery that is discharged or completely depleted will only last about 300 cycles, however if the same battery is discharged up to a maximum of 50% of its capacity could cycle 3000 times over it life period; again if properly maintained.
Battery use in colder temperatures:
When batteries are rated, they are rated at 25 degrees Celcius. When the temperature drops the capacity to hold a charge drops too. If your batteries are to be stored outside where the temperature drops below freezing, the reduction in capcity must be taken into account. Use a wooden skid, to allow for temperature circulated evenly around the battery.
Storage of Batteries:
The storage of batteries, should be stored in a well ventilated area. When the batteries are charged to full capacity and left to charge continuously, hydrogen gas can bubble out of the electrolyte and can cause a fire hazard. To prevent this, the battery enclosure should be vented to the outside.