Lithium - ion solar batteries have multiple benefits. Their energy density is high, translating to more power stored in a smaller area. The long cycle life of lithium - ion batteries means lower replacement frequency, and their self - discharge rate is lower, meaning stored energy can be retained for longer. With lithium - ion batteries, a more stable discharge voltage is guaranteed alongside a wide-operating temperature range. The major downside is the increased cost. Regardless, their lower maintenance requirements, extended lifespan, and superior performance, make them the predominant option in solar applications.