I agree with David. I think the first 1.25 is for continuous use, and the second is for when irradiance is higher than the standard 1000w/m2. I've also seen irradiance around 1200 in cloudy central NY.
On Mon, May 18, 2026, 3:36 PM David Quattro via RE-wrenches < [email protected]> wrote: > The standard assumed irradiance for math purposes has always been > 1000W/m2. I’ve seen days where base-line was 1200 on my Daystar meter, and > elevation was barely above sea level, say 500ft, max 1000ft. I imagine Edge > of cloud effect on a day like that could send the current as high as 1.56 > David > > > > On Mon, May 18, 2026 at 6:24 AM Dana Orzel via RE-wrenches < > [email protected]> wrote: > >> VERY High elevation 10,000’+ , with high wind & very low temps. Not >> normal installation definitely a “Special” situation. I agree in 95% of >> installations 1.56 is an excessive. >> >> >> >> _________________________________________________________ >> >> Dana Orzel GREAT SOLAR WORKS! >> >> C – 208.721.7003 E – [email protected] >> >> W - www. greatsolarworks.com www.solarwork.com >> >> *“Responsible Technologies for Responsible People since 1988!”* >> >> >> >> >> >> ---------- Forwarded message ---------- >> From: Drake Chamberlin via RE-wrenches <[email protected] >> > >> To: RE-wrenches <[email protected]> >> Cc: "[email protected]" < >> [email protected]> >> Bcc: >> Date: Mon, 18 May 2026 13:09:27 +0000 >> Subject: [RE-wrenches] 1.56 Rule >> >> The logic of this rule for calculating PV amperage seems a little off to >> me. - It is a calculation that is set in stone as a bedrock truth of the >> solar industry. (1.25 X 1.25 = 1.56). >> >> The multiplier of 1.25 for a continuous load is relevant for sure. To >> multiply again by another 1.25 seems excessive. >> >> Although it is certainly true that modules put out considerably more >> power when it is cold out, in my experience that is almost all due to the >> increase in voltage. The amperage goes up a little, but no where near 25%. >> >> Just because I haven't seen it doesn't mean it can't happen. Are there >> circumstances where the amperage of a PV module can go up by 25%? >> >> Thanks, >> >> Drake >> >> >> *Drake Chamberlin* >> >> *Athens Electric LLC* >> >> *Ohio Electrical Contractor’s License 44810* >> >> *NABCEP Certified PV Installation Professional* >> -- >> >> _______________________________________________ >> List sponsored by Redwood Alliance >> >> Pay optional member dues here: http://re-wrenches.org >> >> List Address: [email protected] >> >> Change listserver email address & settings: >> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >> >> There are two list archives for searching. When one doesn't work, try the >> other: >> https://www.mail-archive.com/[email protected]/ >> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >> >> List rules & etiquette: >> http://www.re-wrenches.org/etiquette.htm >> >> Check out or update participant bios: >> http://www.members.re-wrenches.org >> >> _______________________________________________ > List sponsored by Redwood Alliance > > Pay optional member dues here: http://re-wrenches.org > > List Address: [email protected] > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > There are two list archives for searching. When one doesn't work, try the > other: > https://www.mail-archive.com/[email protected]/ > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > http://www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > http://www.members.re-wrenches.org > >
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