On Fri, Mar 22, 2024 at 10:48 PM, Steve T wrote:
So you're saying that as the controller pulls more current from the solar panel, the voltage from the panel drops, and depending on how fast the voltage drops, that will determine what current produces max power?
That's basically correct. Think of the two extremes: zero voltage and maximum current, or maximum voltage and zero current. Both yield zero power. Somewhere in between is the MPP. If the panel looked like a battery in series with a resistor, that would be at half the open circuit voltage. However, that's not what the panel looks like, as you can see from the voltage vs current curves.
The MPP depends on illumination, so the controller is constantly adjusting, but it is usually close to the open circuit voltage point. That's usually well above 12 Volts, so the battery current will usually be higher than the panel current.
I wasn't able to measure voltage coming from the panel because there are no exposed connection points.? I'll have to make something to measure that.
You can calculate the panel voltage by dividing the power by the current.
Scott Ellington
