Their lifespan varies by type and manufacturer. Between 400 and 800 cycles at 50% DOD for gel or AGM batteries and between 1000 and 2000 cycles for OPZV and OPZS batteries. These lifetimes announced by the manufacturers are to be modulated because they result from tests carried out under standard conditions. If the solar batteries cycle at discharge levels higher than 50%, the number of possible cycles decreases rapidly and therefore also the battery life. To avoid this reduction of cycles, the inverter and the charger must be parameterized according to the manufacturer supplied cycle / DOD curves, installed in a heat-protected and ventilated area and have no load and discharge currents above 15% on average of the storage capacity.
For decades, solar lead batteries (gel, agm, opzv, vrla ...) are used for energy storage. These solar batteries are reliable and much cheaper than lithium batteries.