Hi, I would like to create a relatively small reference solar cell in order to estimate the maximum available solar power for a larger solar power plant.
My plan is to use a 40 Wp solar cell and an existing MPPT charge controller. In order to get the maximum power from the cell, the power extracted needs to be consumed on a load somehow. This load should be the simplest possible (like a power resistor) but it should also be variable in order to get the maximum power from the charge controller's 12V output. For the power calculation, the solar panel's output voltage and current would be measured.
The more I think of this, the more it seems like I need to build an MPPT control loop just for the load that might make the existing MPPT charge controller not needed at all. Is this really the case or there some easier solutions that I couldn't come up with? As you can see my goal is to just dissipate the power generated from the solar cell. I also thought of a battery as a buffer but I am looking for the simplest solution.
When my old company built solar charge controllers, they did exactly what you are questioning. We used an array of small incandescent lights, all voltage rated for the controller being tested.
I use dump loads for my wind turbines but not for my solar array's. Why do you want a dump load for solar? If you got excess charge capacity then get more batteries to charge.
My goal is to achieve a reference value that is the proportion of the present maximum solar power and the nominal solar power. The setup would not be used for any energetic purposes, only for signaling the above mentioned percentage value. Batteries would work fine but I want it as dumb, cheap and reliable as possible.
I don't see how you can do that without using the exact parts that the real setup will be using. A smaller panel would be ok, but a different MPPT and load will have different efficiency.
I think you're asking for a power zener, like the 1N3312.
Leo..