Amp-Hours: To learn how much usable power you actually have, you need to understand amp-hours, or the total capacity of the battery. Amp-hours are typically based on 20 hours of total available use, unless otherwise stated on the battery. To figure out how many amps per hour, simply divide the amp-hours (AH) listed on the battery by 20 (or another number if specified on the battery):
Batteries: Lead-acid batteries are the most commonly used type in RVs. Somewhere in your rig, you will find a panel that shows you approximately how fully your batteries are charged. It is inexact, especially if your batteries are not “at rest” (not draining or being charged for at least 30 minutes), but it will give you a reasonable idea. It’s not harmful to drain lead-acid batteries completely, but to maximize their lifespan, try not to let them go below 50% without a recharge. Newer lithium-ion batteries are more user-friendly for a variety of reasons, but due to costs, they are not yet popular in RVs.
Types of Solar Panels: Solar panels come in two types—monocrystalline and polycrystalline. Monocrystalline panels are slightly more efficient, but they are also more expensive. If you have a small RV with little roof space, monocrystalline panels can be physically smaller for the same output. If you have the space, though, cheaper polycrystalline panels work just fine.
Flexible vs. Flat Solar Panels: Flat solar panels are less expensive and more durable than flexible panels, and usually have a longer warranty. However, flexible panels are lighter, more aerodynamic, easier to mount, and in some cases (such as on an Airstream) more aesthetic. Choose whichever makes more sense for your rig.
Solar Charge Controller: Solar panels typically provide 16 to 20 volts of electrical potential. An RV battery can handle 12 volts. A solar charge controller is a standard part of an RV solar installation. It regulates the voltage and current to prevent battery damage. The standard controller is fine unless you have an unusual setup or use your RV in extremely cold conditions.