Wednesday, May 5, 2021

Profiling my Bioenno folding 100W solar panel with CBA

We had a sunny and completely clear day here with low humidity and no clouds whatsoever. A perfect day to profile my new 100-watt Bioenno folding solar panel.

I've had a Computerized Battery Analyzer (CBA) for many years now but have never used it to profile a solar panel. A short write-up on the process is available on West Mountain Radio's website. I've read it several times and had the process on my to-do list for some time now.

As you may be aware, there are two broad categories of solar controllers: Pulse Width Modulated and MPPT.

MPPT stands for Maximum Power Point Tracking and is the more efficient of the two types. Several factors determine the maximum power capable of being extracted from a given solar panel: mono- or poly-crystalline construction, temperature and load characteristics, to name a few.

The CBA allows the load to be changed over time during which a plot is drawn. That plot can be Voltage and Current or Power and Current. The set-up allows for a variety of current steps and a user-selectable amount of time to let the analyzer stay at a particular current setting.

Set-up screenshot
 

Load characteristic in this case is the battery analyzer, which changes the load it presents to the panel. In actual usage, the load would be an MPPT solar controller, changing the load presented to the solar panel in order to extract maximum power for charging batteries. 

For my test I chose to increment the current taken from the panel in 100mA steps and to spend 10 seconds at each step. I ran this test at my local astronomical noon (1:20 PM) when the sun was directly overhead and the panel was flat on the ground.

There are a lot of ways to make ~100 watts from a 100W panel. In my case it occurs at 17.8 volts and 5.28 amps. Or, more to the point (the Max Power Point, that is) with a load resistance of 3.4 ohms.


This is actually 94 watts. Close enough.

Next I graphed Voltage vs. Current. I'm not sure what useful info this provides but it was available to be done by the CBA, so I did it.

I'm very happy with the the foldable panel. It is fairly lightweight, not too expensive and performs well.

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