Solar batteries fall into three main categories. From least to most expensive, they are:

• Flooded lead-acid (FLA)
• Sealed lead-acid (SLA)
• Lithium-Ion

Flooded lead-acid batteries use a tried-and-true technology that is more than 100 years old. They require monthly maintenance to stay operational. The main task is refilling the battery with distilled water, which evaporates during the charge cycle.

Sealed lead-acid batteries also use a lead-acid chemistry, but are sealed to prevent off-gassing. They are also maintenance-free, which removes the need for monthly checkups. Go with a sealed battery if you don’t mind paying a bit more for convenience.

Lithium batteries are the premium option. In addition to being maintenance-free, they charge faster, endure deeper discharge cycles, and have a longer lifespan. They cost the most up front, but could last 2-3 times longer than the other options.

We compare the most common solar battery choices in our lead-acid vs. lithium battery breakdown.