There are a few different charge controllers you can use to regulate the charge to your batteries.
- PWM (Pulse Width Modulation)
- MPPT (Maximum Power Point Tracking)
Regulators are the most simple charge control devices. They allow the battery voltage to rise up to a pre-set level and then simply shut off until the battery voltage drops below a certain voltage.
PWM controllers are a little more sophisticated. The PWM controller constantly checks the battery voltage and modulates the amount of time the charge voltage is applied to the battery bank. The closer the battery voltage is to the desired level the shorter the bursts of charge sent to the battery. Now there is a downside yet. If you have a 36 Cell PV (Solar) module that will try to deliver 18 V and your desired battery voltage is 13.5V you are only utilizing approximately 75 % of the power available. So a 100 W PV module will actually give you a maximum output of 75W.
MPPT chargers will actually make use of nearly 100 % of the available power. In simple words, it will take all the power from a module available and condition the voltage and amperage to the ideal battery voltage. Many MPPT Charge controllers can actually handle much higher voltages than the battery. By connecting multiple modules in series you will increase the voltage yet the current stays the same. Be mindful, MPPT chargers have a maximum “DC” input voltage. The MPPT charge controller is the most advanced and also the more expensive solution. However, it saves you money on the wiring, module and racking investment. In my opinion, money well spent.
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Have a sunny day,
Renewable Energy Solutions
48 Feltham Rd.