Originally Posted by psmd
Good evening all
Have a 2021 GL and was recently monitoring the wattage production from the roof.
I was in full sun on a blue sky day-(clean panels) and was seeing about 125 w on the Victron panel.
Felt like that a is a little low but don't have a reference. (3) 100 W panels should produce 300?
Wondering if there is a way to tell if my panels are workiing?
Panels produce 100% of the rated output at the earth's equator at noon, when the sun's rats are perpendicular to the the panel.
Seriously, the rating standard is designed to reproduce that level of solar input as the standard by which all panels are measured.
Obviously, we don't live at the equator, so the additional atmosphere the sun's radiation has to travel through in Northern latitudes will scatter more of the rays and reduce the intensity of the solar radiation by the time it hits your panels.
That is degradation factor #1.
Number 2 is that the panels on your roof will never be oriented perpendicular to the sun's rays.
So the steeper angle of incidence is degradation factor #2.
Solar panels are rated at 77F and their output reduces as the sun heats them up beyond 77F.
So high temperature is degradation factor #3
Dirt and other debris can shade the cells in the panel. Shading is degradation factor #4.
These are the main factors.
The key takeaway here is that your peak output in ideal conditions in North America is going to be on the order of 60-70% or so of the total panel wattage ratings. Clouds, shade, dirt, hot panels will all reduce the output.
I have 700 watt high efficiency panels on my Airstream. I get around 400watts in ideal conditions (no clouds, no haze, no shade, clean solar panels, and bright sun on a cool day, with most of my panels somewhat oriented towards the sun). That's around 60% of my total wattage rating. I might get a bit more in Arizona :-)