When you build a solar system, you have three main battery options: flooded lead-acid battery, sealed lead-acid battery, and lithium battery, but have you heard of them?

   (1) Flooded lead-acid battery (FLA)

    The distinguishing feature of FLA batteries is that the plates are submerged in water. These must be checked regularly and refilled every 1-3 months to keep them working properly.

    Inadequate maintenance can shorten the life of the battery and void the warranty. FLA batteries also need to be installed in a ventilated enclosure to allow battery gases to escape.

    (2) Sealed lead-acid battery (SLA)

   There are two types of SLA batteries, AGM (Absorptive Glass Mat) and sealed gel batteries, which share many similar properties. They require little maintenance and are spill-proof.

   The main difference between AGM and gel batteries is that gel batteries tend to have lower charge rates and outputs. Gel batteries generally can't handle as much charging current, which means they take longer to charge and output less power.

   (3) Lithium battery

   The best lithium battery chemistry for solar applications is Lithium Iron Phosphate, shorted to LiFePO4 or LFP cells. This new technology has a longer lifespan and can go through deeper cycles. Unlike lead-acid batteries, they also require no maintenance or ventilation.

   Lithium batteries have a higher upfront cost, but the extra efficiency means you can spend less per kilowatt-hour of capacity over the life of the battery.