backchannel: MPPT and Vpanel, pt 2

Thus it continues.

It can only reduce the voltage going out of the controller. The MPPT controller can manipulate the amps when there is sufficient need from the battery.

First, demand can come from loads as well as from battery charging.  Thinking that all demand comes from charging is what gets people lost in “PPT only in Bulk” territory.

Second, the PPT controller extracts power from the panel as needed.  It does this by tweaking panel voltage (Vpanel).

Consider the following (and really huge) power curve.  It’s the heavy solid arc:


If you know a particular voltage you can look at the curve to find power at that voltage.

So what happens if you force the panel to run at that voltage?  That’s right, grasshopper.  You extract that amount of power (W) from the panel.