What Is a Charge Controller and Why Do I Need One?

If you are dipping your feet into the solar waters you may be overwhelmed by the number of components which make up a solar PV system and be unsure of how to choose those specific components to put together the best system for your home and your specific needs. Because a charge controller enables you to monitor battery charging, thus avoiding over or under-charging, then if you are planning an on-grid system, you won’t need a controller. If you are contemplating on off-grid system using batteries, are planning to use solar and wind power in the same system, or are merely planning a backup power source for outages-which requires batteries-then you will need to choose a good charge controller for your system.

Solar panels and wind generators both produce electricity, however those outputs vary significantly depending on the available sun or the wind speed. Because of this variability, the output must be converted to something which is a little more consistent, which is where your controller comes in. Whether your batteries are sealed or gel, your controller will make sure they are charged in a consistent manner. If you are using a wind generator, the charge controller is probably either built into the unit, or comes as part of the package, so you won’t need to choose one separately, however if you are only using solar panels to power your home, then you need to know how to select the best charge controller.

Different Types of Charge Controllers

There are several different basic types of charge controllers, the first being the series cycling controller which is probably the simplest; the series cycling controller prohibits overcharging of your batteries simply by turning your solar panel’s current off and on based on the battery voltage. If the battery voltage is to nearly full charge, a mechanical relay on the controller shuts off the charge. When the battery voltage begins to fall and gets low enough, the charge controller kicks back in.


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