It is interesting. I don't mppt my panels, as it is so cheap to just buy more and have no pesky electronics in the way.
Because of this preference, I buy low voltage panels.. ie only 66 cells instead of 72 cells. This makes the mppt less of an interest, as the differential between the SOC and Voc is not that big.... so mppt would not yield the normal 20-30% on a sunny day... add to that the marine environment, and clouds are normal... so trackers are of little value either.
Because of this lassitude and indifference, I have not noticed the voltage drop associated with temp. I make no attempt to have air beneath the panels either... complete heathen.... so temp is very high in summer.... even through the thin cloud.
Given the above, I have only noticed better and worse operation from photon activity, and the space charge width differentials have not been noticed at all.... ie the built in voltage has made no difference to me, as I have used the cell as a current source X battv, not a VA source persay.... where mppt would make a real difference.
Can't work out how to tell if the power drop ( if I can see it) with temp, is because the forcing volts are down, and so synchronous impedance is damaged, or the forcing voltage plays no part, as the cells are current sources not voltage..... must ponder this further.....
I have been wondering at that particular effect, but have not been able to discern it at this stage.... guess that is what happens when you don't log.... and with batteries filled by 9-10am, I guess I struggle to get serious about it, but I would like to test for this sometime.
Maybe I should just measure Isc under hot and cold conditions (hot then run the hose over it), and see if that materially changes....hmmm..