Edge of Cloud Effect.

Hi Guy's,

I would like to convey an explanation for the current surge that I think is more accurate.
First we should all be aware that every solar panel has a temperature coefficient.
I am using Sunpreme GBX340 which has a coefficient of Pmpp = 0.28%/ C
This is a very low number. SunPower is 0.3% and many of the other China models are very high ~0.4% to ~ 0.5% and I expect some don't specify their number because it is so high.
I have Solar Edge Optimizers on each panel so I can observe each panel's power every few minutes.

I see a power increase when:

Sun angle rises over Tree Shading Lower 4 panels at 12:30pm power is high and then declines in the next 3 minutes as the panels begin to heat up.
Water is flowed over Panel reducing temperature. Power increase is approximately 0.28% Power increase for each degree C drop
When I go from cloudy to Sunny condition abruptly.
When I cover a panel with card board long enough to lower its temp and then quickly remove it.

So in conclusion temperature of the panel plays a factor here.
A good test would be to use an Irradiance meter on a Sunny day versus a transition from clouds to Sun and see if it is wildly different. I suspect that is not.

If you can test individual Panel power
Another good test is get Laser Temp Reader and big piece of cardboard. On Sunny day where the panel is running over 100 C cover it with cardboard for 10 minutes and check its temp
then remove it abruptly validate the power increase based on the temp coef.

Some examples

Fahrenheit
Celsius
Delta C


75
23.9



105
40.6
16.7



0.28% * 16.7 = 4.67%
0.4% * 16.7 = 6.68%
0.5% * 16.7 = 8.35%

a poorly designed panel may heat up more
for example.


Fahrenheit
Celsius
Delta C


75
23.9



120
48.9
25.0



0.5% * 25C = 12.5% (This is a big number)