How do solar charge controllers work?

May 17, 2023

Solar charge controllers are specified in both current and voltage. You will need one that can withstand the voltage of your solar panel, and then transmit it to the battery pack voltage (typically 12, 24 or 48VDC). Next, you will need to make sure that the solar charge controller has enough capacity to handle the current (in amperes) coming from your solar panel group. Take the power of your solar panels and divide it by the battery voltage to get a rough estimate of the number of amperes needed by the controller.
Another way to size a charge controller
The basic formula for sizing one is to take the short circuit current (Isc) from the matrix and multiply it by 1.56. Make sure that the solar controller you select can handle at least as many amps.
Be sure to protect this important part of your system with proper over-current protection before and after the solar controller (see Enclosures, Electrical and Safety for Options).

Types of Solar Charge Controllers

What is PWM & MPPT?

Now that you know what solar controller size to look for, identify the type of solar charge controller best suited to your application: MPPT or PWM.

MPPT Solar Charge Controllers

The MPPT solar controller (Maximum Power Point Tracking) is the star of modern solar systems. In fact, these controllers detect the optimal operating voltage and amperage of the solar array group and match them to the battery bank. This results in 15 to 30% more power on your solar generator compared to a PWM solar controller. Although the MPPT solar charge controller is more expensive than its PWM counterpart, it is usually worth investing in any solar electric system with more than 200 watts.

PWM solar charge controllers

A PWM (Pulse Width Modulated) solar charge controller is of the traditional style. They are robust, inexpensive and widely used in solar panel applications. PWM bypass controllers are used less often and mainly in applications where electrical interference is a problem.
Features and add-ons for solar controllers
Once you have chosen a type of solar charge controller, you must identify the features you need. There are many basic solar charge controllers that work well. In addition, some exciting features will further enhance your renewable energy experience. Battery temperature sensors are an important addition to your system. The capacity of the battery depends on the temperature. Therefore, a temperature sensor can significantly improve the battery charge.
In addition, some solar controllers offer adjustable control voltage setpoints, low voltage disconnection, overload protection, and counting. If you plan to use a DC load, you can connect it directly to the solar charge controller. If the solar controller is equipped with low voltage disconnection (LVD), the solar charge controller can detect when the battery is low and shut down the DC charge until the battery is charged.

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How do solar charge controllers work?

How do solar charge controllers work?

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