Any explanations for production loss at solar noon?

[sunshine_eggo]

You will need to use distilled water or your panels will become encrusted with some nasty hard-to-remove mineral deposits fairly quickly.

edit:

Mike C. posted the same time as I did about this...

Rainwater has a typical TDS of 20 mg/L (20ppm). That's about what you get with typical tap water run through R/O.

I think the only particulates are going to be the ones washed off the panels.

Mine's the WS-2902 or very similar to it, and I'm happy with it. 3 years now still going fine. I set it up to report to wunderground so I can just check my wunderground station page for historical data and graphs. The base station wifi setup is a little finnicky but functionally works fine once set up. My outdoor is 100ft from where the living room base station lives and never has signal problems.

Acurite Iris on WU as well. Very pleased with it.

 

[sunshine_eggo]

The voltage still rises with increased light levels- more slowly, but it does still rise...

Worse, many people use Voc and Vmp interchangeably, (some even use the 'sales talk' of '12v panels', '24v panels', and use THAT as their basis for the PVmax rating....)


Some of the things I have seen done...
urgh....

For clarity:


when you look at specific charts for specific panels, it's about 2-3% between 200W/m^2 and 1000W/m^2 and whatever values these are, they're shifted down by the temperature coefficient.

 

[glandpuck]

"It implies that the panel is generating more power than its rated power, which is not possible."

Of course that is possible.
Why do you suppose NEC says to size fuse and wire for 1.56 Isc?

Panel label is for laboratory conditions of 77 degrees and a certain radiance on the panel. then there is another rating like NOC. Put them outdoors, you may see brighter sun and temps lower than 77 and your panel output will be above the label. Same with edge effect. In edge effect, high partial clouds and sun can result in the panels being directly illuminated by the sun itself and then the sunshine strikes the cloud edge and reflects off of them like a mirror right onto your panels creating a two sun situation on your panels, the so called edge effect and this results in higher than label output.

 

[mciholas]

Rainwater has a typical TDS of 20 mg/L (20ppm).

Not after it has washed over a dusty roof, through pipes, into a collection tank.

There is a difference between rain water directly hitting the panels, and collected rainwater being used later to spray the panels. The collected rain water picked up dust that settled on the roof.

We all know this because we know rain water cleans panels. Well, where did that dirt go? It went into the run off water from the panel. If you catch that and pump it back to the panel, you are putting it back.

Now if you want to filter and treat the rainwater before using it, you can, but that's added complexity and possibly some power to do that.

A combo PV and water panel would be different since it is a closed system without evaporation.

Mike C.