If you use 100% duty rated breakers such as breakers sold my Midnite,
you can ignore the 1.25 multiplier for continuous duty.
Ray Walters
Remote Solar
On 5/18/2026 8:27 AM, Dave Tedeyan via RE-wrenches wrote:
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]
<mailto:[email protected]>
W - www. greatsolarworks.com <http://greatsolarworks.com>
www.solarwork.com <http://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/
--
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