How many panels are actually generating solar power?

[h2ofun]

Will you be able to check to make sure it is operational before a return timeframe runs out? Otherwise you may have a dud on the shelf.

I will just stick with SE warranty. They got me a replacement unit in less than a week. And I still want warranty support from my installer, so
no way did I install the replacement one, even though it sat in the box in my garage for 5 days.

 

[sorka]

Will you be able to check to make sure it is operational before a return timeframe runs out? Otherwise you may have a dud on the shelf.

I wouldn't do it unless I was willing to swap it just to check and also to get it on another SE account.

 

[charlesj]

I will just stick with SE warranty. They got me a replacement unit in less than a week. And I still want warranty support from my installer, so
no way did I install the replacement one, even though it sat in the box in my garage for 5 days.

In a sense I was rhetorical in my response about buying a used one, not knowing its actual condition beyond a verbal ok from seller.
Didn't expect it be installed to check.

 

[Skotty]

I had solar installed a few years ago. It's common practice for the panels to be rated higher than the inverters. It's called oversizing. Then there is time of year, angle and direction panels are facing, cloudiness/haziness, shading, etc that can all play a part in reducing output from theoretical maximum. Big difference between winter and summer. In January (winter), mine produces about 330 kWh. In July (summer), mine produces about 850 kWh. That's a combination of typical weather patterns, day length, and sun angle, making for a dramatic difference between seasons.

 

[sorka]

Also, keep in mind the panel rating is the DC rating before going through the inverter. It will always be quite a bit less when it comes out AC.

 

[charlesj]

Yep, oversizing is great when you can. An DC to AC ratio up to 1.5 is what the commercial industry is doing from what I hear.

 

[Puma2020]

Plus the temperature matters. Solar panels tend to be less efficient on warmer days. Your panel specs should indicate how much.
The inverter's rating was a great first thing to determine,
Then you have to measure
the amount of humidity (i.e. clouds, even wispy ones),
dust or other pollutants,
the sun's angle .vs. the panel's angle (if it's not 90 degrees you lose some %),
the temperature
Were the panels washed recently, any dust on them? Any scratches?
There are a LOT of factors that determine how much production to expect from a panel.

Here is what my 8.16 kWh system produced in 2020.