What solar panel should I get?

Does an mppt charge controller get its energy to operate from the solar panel directly, or from the battery?

• Does the charge controller get its "energy" to operate from the solar panel its self or does it get it from the battery bank?

• Answer:

  Hey Michael, Mary Grace has a very good description of what an MPPT controller does, but I'm not sure it answers your question directly. In a stand along system like ours, the MPPT controller will capture a very small amount of the electricity flowing from the panels to the batteries to operate it's own circuits, including the digital counter that keeps track of the power produced. But the device still needs a small amount of power at night when the panels are not producing anything, much like a television set might be turned off, but still uses a watt or two to operate the receiver for the remote, waiting for the moment the user might want to turn the set on. So to answer your question directly, the controller gets its small power usage from wherever it can. A grid tied system has the same issue, at night the controller is using a watt or two of power from the utility grid to keep track of things, waiting for the voltage on the array to increase at sunrise, when it will begin getting its power there instead. It's a necessary energy use, at the end of the day the controller might use 20 watt hours, much like a LCD digital clock, but it increases the output of the array by 10 to 50 times this amount throughout the day, more than earning back its usage. We lost our MPPT controller in a lightning storm several years ago, and I replaced it with a simpler Pulse Wave Modulator (PWM) model, which also has a digital counter and needs the same one watt or so at night to keep track of things, so it doesn't matter which controller you have, some of your power harvested is used up in controlling the harvest process. Take care Michael, Rudydoo