Gel batteries, AGM batteries, and lithium batteries are commonly used in solar energy systems. Gel batteries use a thick electrolyte gel that prevents acid leakage, making them maintenance-free and suitable for deep cycle applications. AGM batteries feature absorbent glass mat separators that hold the electrolyte, ensuring spill-proof operation and high cycling capabilities. Lithium batteries, on the other hand, offer higher energy density, longer lifespan, and lighter weight compared to traditional lead-acid batteries. They provide efficient energy storage, faster charging, and can be deeply discharged