[RE-wrenches] Insolation calc anyone ;)

[Solar]

I live in Northern MN and we get very cold days (-50F +) and very crisp clear days when it’s this cold. I’ve seen 1333 WM2 on the same plane as my array with snow reflecting sun light. Using the daystar irradiance meter. I am at 1400’ so your increased elevation with very cold temps, snow and edge of cloud could maybe cause it. Maybe a calculation of extremes could give you an idea. Rearrange the formula and get the irradiance needed to cause this high of watts. 

Jesse Dahl

NABCEP PV Installation Professional
IBEW Local 292 - Electrician 
Electrical/Solar PV Instructor - HCC

Sent from my iPhone

> On Nov 22, 2018, at 12:10 AM, <bruce at willpowerelect.com> <bruce at willpowerelect.com> wrote:
> 
> Compadres,
> 
> I have 4 identical arrays of 3 strings of 3 Solarworld SW 245 mono (2010 model) to FM80s. When designing, not exceeding 150 voc was critical. No record temp data available. Location ~ 4,000' Pacific Northwest. Recently replaced an FM80 with 6 blown FETs showing max power at 3075 watts! This from a 2205 watt array into a 24 volt battery. Max historical voc is ~120. My guess at record low temp is -10F. tc%/ºC MPP doesn't get anywhere close. What would the WM2 need to be in order to achieve 3075 watts on a 2205 watt array? BTW, 2 of the four original chargers are still working fine and one of them also shows 3075 watts max power. Edge of cloud effect against snow field at bottom of array?
> 
> Cheers,
> 
> Bruce Fiero-RMI
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