1400 W/Sq M would certainly do it!
Thanks for all of your input.
Drake
---
On 2026-05-18 16:26, Zeke Yewdall via RE-wrenches wrote:
I've definitely seen this. I regularly measured over 1200 watts/sq
meter in clear day skies on my sites, and if you throw in some edge of
cloud too... could get even more. I've heard ski resorts dealing with
1400 watts/sq meter on vertical windows of lodges facing a big snowy
bowl. I'll try to dig up a graph from one of my sites with monitoring
on it. I was often getting near STC voltage at the same time. These
were high elevation (8,000 feet and up) sites in Colorado, no humid
haze, thinner atmosphere, and often a bunch of snow reflection too. I
would measure around 3.6kW peak AC output from a 3.3kW STC rated array
at my house at 9,300 feet there (had it on a 3.8kW inverter -- I
greatly disagree with certain inverter manufacturers recommendations
for overpaneling, but that's a different topic).
If you're closer to sea level or back east where the humidity blurs out
the sun more, probably a lot less chance of it, except during good edge
of cloud conditions -- which generally don't last longer than 5 or 10
minutes max -- not three hours like altitude/snow enhanced irradiance.
I will say, the sun breaking through the clouds on a 95% humidity 70
degree day in DC felt hotter than any 95F day in the sun out west --
did not put an irradiance meter on it though.
I have some rear facing irradiance monitors on some sites now, to get a
better idea of how much gain we can really expect from bifacial
modules. Be interested in seeing what they say over time. I've been
doing another 1.2 or 1.25 factor when using bifacial modules in snow
country, but not sure how realistic that is.
Zeke
Are there circumstances where the amperage of a PV module can go up
by 25%?
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