All solar power systems that use a battery need to use a solar charge controller. The charge controller is put in place to regulate the amount of power that goes into the battery. This is done to make sure that the batteries are not overcharged, as they can become damaged and the battery life can be reduced. In extreme cases of excessive overflow of power the battery can become unusable. The two types of solar chargers MPPT and PWM perform the same job, but are slightly different.
MPPT Charge Controller
The MPPT or Maximum Power Point Tracking charge controller has recently emerged on the market and it is fairly new. This type of charge controller has the ability to convert excess voltage into amperage. Because of the type of batteries most solar systems use (usually 12 volt batteries) the MPPT voltage converting capabilities can deliver even more voltage than is required for the batteries to be charged. The voltage that is converted into amps is used to keep the charge voltage at optimal level and as a result the battery is charged quicker. Because of this feature the MPPT allows your solar system to operate at optimal levels all the time.
PWM Charge Controller
The more modern version out of the two is definitely the PWM or Pulse Width Modulation. PWM works by slowly reducing the amount of power that is transferred to the battery, as it gets closer to being fully charged. The solar PWM charge controller works that way in order to reduce the amount of stress that is inflicted on the battery while it is being charged. As a result, the battery has a longer life span and it can be kept fully charged or “float” indefinitely. PWM are definitely the more complex option out of the two, but the solar PWM charge controller has no mechanical connections and nothing to break.
Now that we have talked about the key features that distinguish the two types, let’s take a look at their similarities and what modern charge controllers can offer. The one aspect that these devices share is preventing reverse-current flow. Believe it or not, electricity can flow backwards, which means at night when solar power is not being collected, electricity can travel through the batteries and through the solar panels and drain your battery. That is why the charge controller has a built-in sensor that detects when no solar power is coming in and automatically disconnects the panels from the battery preventing reverse current flow.