Humidity affecting solar panel output.

[Mattb4]

As I was monitoring some new panels today it seemed as if the wattage output was not in line with my expectations. Given that the day has thin clouds which partially block some sunlight, also the outside temperature is 84F, all of which effect output as well as any wind blowing past, there is another factor at play. Humidity is high with a dewpoint of 70. It is muggy as all get out.

So I wondered does humidity reduce solar panel output? Doing some research the answer is a resounding Yes. I found this article that goes into it rather nicely. https://www.researchgate.net/public..._on_the_efficiency_of_solar_cell_photovoltaic

So if your panels are not doing as expected it may be more than just if the day is sunny or not.

 

[svetz]

I plotted last year's humidity and efficiency (watts from the light meter vs watts from the panel adjusted for temperature) data to see if I could spot any trends, but it was just noise as far as I could tell.

Update: Reflecting on it, the data makes sense because the light meter should be affected too.

 

[Supervstech]

A huge greenhouse gas everybody ignores is water vapor. So it makes sense humidity would reduce solar irradiance.