Charge controllers are one of the most important parts in your entire RV solar panel system.
There are three main functions a charge controller does:
It keeps your batteries fully charged
It prevents your batteries from being overcharged
It prevents your batteries from being excessively discharged
Batteries are a key component in your RV solar powered energy system. Without batteries, you can only use the power your solar panels generate when the sun is out and you won't have any power at night when you could really use it.
Since RV solar panel systems almost always gather power and store it in batteries, nearly every system is going to require a charge controller. A solar charge controller is designed to protect your batteries from being overcharged by your solar panels and it will block any reverse current (from the batteries) as well.
Solar panel charge controllers are specified by both amperage and voltage. For example, if one module in your 12 volt system produces 3. 5 amps and you've got four modules then you're producing 14 amps of current at 12 volts. Because of light reflection and the edge of cloud effect, power output can spike above expectations. For this reason you need to increase the controller amperage by at least of 25% making the minimum rating your controller to 18 amps.
Don't worry about ever getting a charge controller that is rated 2 or more times higher than your solar panel array. It's not in any way a bad thing. In fact it's actually better for two reasons:
Your system will always be protected
You can add more solar panels in the future without having to change your controller.
