Typically, yes. If your solar panels are larger than five watts, you’ll need a charge controller. Charge controllers perform the important functions of preventing the overcharging of batteries by limiting the amount and rate of charge to your batteries. Additionally, they shut down your system if the stored power falls below 50 percent capacity and charge batteries at the correct voltage level. This helps preserve the life and health of the batteries in your battery bank.

There are two types of charge controllers to consider: Pulse Width Modulation (PWM) controllers and Maximum Power Point Tracking (MPPT) controllers. PWM charge controllers are cheaper and ideal in smaller applications. They’re an older technology and are cheaper, but they are less efficient than MPPT charge controllers. MPPT controllers are the most efficient, ideal in large applications, and are the most expensive option. Both are widely used, have similar lifespans, and preserve the life of your batteries.

Charge controllers are sized based on your solar installation’s voltage and the array's current. To determine what size system you need, we recommend using the Renogy solar calculator . You typically want to make sure you have a charge controller that is large enough to handle the amount of power and current produced by your panels. If your solar system's volts are 12 and your amps are 14, you would need a charge controller that had at least 14 amps. However due to environmental factors, you need to factor in an additional 25%. This brings the minimum amps that this charger controller must have to 17.5 amps. In this example, you would need a 12 volt, 20 amp charge controller.