A Solar Charge controller, charge regulator or battery regulator limits the rate at which electric current is added to or drawn from electric batteries. It prevents overcharging and may protect against overvoltage, which can reduce battery performance or lifespan, and may pose a safety risk. It may also prevent completely draining ("deep discharging") a battery, or perform controlled discharges, depending on the battery technology, to protect battery life. The terms "charge controller" or "charge regulator" may refer to either a stand-alone device, or to control circuitry integrated within a battery pack, battery-powered device, or battery recharge.

Charge controllers come in various types. Solar charge controllers regulate the charge from a solar panel array to a battery bank.

PWM

A PWM (Pulse Width Modulated) solar charge controller is the traditional style. They are robust, inexpensive and widely used in solar panel applications.

MPPT

The MPPT (Maximum Power Point Tracking) solar controller is the shining star of today\'s solar systems. These controllers actually detect the optimum operating voltage and amperage of the solar panel array and match that with the battery bank. The result is additional 15-30% more power out of your solar array versus a PWM solar controller. Although the MPPT solar charge controller is more expensive than its PWM counterpart, it is generally worth the investment for any solar electric system over 200 watts. Since renewable energy power systems almost always gather power and store it in batteries, almost every system requires a charge controller. A solar charge controller will protect your batteries from being overcharged by your solar panels and it will block any reverse current (from the batteries) as well. Solar charge controllers will actually protect every aspect of your solar power system from your batteries to your solar panels. Temperature sensors are an inexpensive addition that help the charge controller more accurately regulate the charge of the battery bank.

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