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Photovoltaic System Component
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PV Controllers |
You will need a controller to prolong the battery life of your PV System. The most basic function of a controller is to prevent battery overcharching. If batteries are allowed to routinely overcharge, their life expectancy will be dramatically reduced. A controller will sense the battery voltage, and reduce or stop the charging current when the voltage gets high enough. This is especially important with sealed batteries where we can't replace the water that is lost during overcharging.
The only exception to controller need is when the charging source is very small and the battery is very large in comparison. If a PV module produces 1.5% of the battery's ampacity or less, then no charge control is needed.
Unlike Wind or Hydro System controllers, PV controllers can open the circuit when the batteries are full without any harm to the modules. Most PV controllers simply open or restrict the circuit between the battery and PV array when the voltage rises to a set point. Then, as the battery absorbs the excess electrons and voltage begins dropping, the controller will turn back on.
Some controllers have these voltage points factory-preset and non adjustable, other controllers can be adjustable.
Controllers are rated by how much amperage they can handle. National Electric Code regulations require controllers to be capable of withstanding 25% over amperage for a limited time. This allows your controller to survive the occasional edge-of-cloud effect, when sunlight increases dramatically. Exceeding the amperage ratings on your controller can destroy it.
Using a controller with more amperage capacity than you are generating will allow you for future expansion and it usually doesn't cost much.
A PV controller also prevents reverse current flow at night. Reverse current flow is the tiny amount of electricity that can flow backwards through PV modules at night, discharging the battery, but the loss of power is insignificant. Only with larger PV systems is this significant but and almost all charge controllers deal with it automatically.
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Products
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ProStar
Charge Controller
Made by MorningStar |
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SunSaver
Charge Controller
Made by MorningStar |
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ASC
Charge Controller
Made by Specialty Concepts, Inc. |
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