I am in debate with a PE over calculation of low voltage of a series string
on a hot day. He insists that an arbitrary high cell temp is factored in,
not just ambient temperature. Could someone please give an accepted formula
for this calculation? Thanks. I cannot find a clear reference to low volt
Usually you increase the temperature above ambient by an amount which depends
on the mounting method. Close to the roof is +35 degrees C, more than 6 inches
above the roof is +30 degrees C, and pole or ground mount is +25 degrees C.
Scott
On Nov 29, 2011, at 11:48 AM, Kirk Herander wrote:
> I
As far as I know, the temperature coefficient holds true whether you are
increasing or decreasing the temperature around the STC temperature of 25C.
Of course, there is going to be a point at which it goes non-linear, but
that is not stated.
On Tue, Nov 29, 2011 at 3:58 PM, Scott McCalmont <
re-wr
] calculating low string voltage
I am in debate with a PE over calculation of low voltage of a series string on
a hot day. He insists that an arbitrary high cell temp is factored in, not just
ambient temperature. Could someone please give an accepted formula for this
calculation? Thanks. I
deg C for most situations.
Best I can do from memory.
DT
*From:* Kirk Herander
*To:* RE-wrenches
*Sent:* Tuesday, November 29, 2011 1:48 PM
*Subject:* [RE-wrenches] calculating low string voltage
I am in debate with a PE over calculation of low voltage of a series
string on a hot day. He insis
wrote:
From: Scott McCalmont
Subject: Re: [RE-wrenches] calculating low string voltage
To: "RE-wrenches"
Date: Tuesday, November 29, 2011, 1:58 PM
Usually you increase the temperature above ambient by an amount which depends
on the mounting method. Close to the roof is +35 degrees C,
On Behalf Of Ray Walters
Sent: Tuesday, November 29, 2011 2:55 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] calculating low string voltage
I'm prepping for a class on this very subject tonight, so I'll just wrap up
everybody's good points:
V min = Vmpp x (1- temp diff x Temp coef
add 15 deg C for most situations.
>
> Best I can do from memory.
> DT
>
> From: Kirk Herander
> To: RE-wrenches
> Sent: Tuesday, November 29, 2011 1:48 PM
> Subject: [RE-wrenches] calculating low string voltage
>
> I am in debate with a PE over calculation of low
Kirk,
You've got some good feedback on this from Ray and Bill. I'll try to add
a little more. Most module datasheets show a normal operating cell
temperature, NOCT, value that's typically 47.5°C. That's 20°C ambient
temperature, 800 W/sq m, and calm wind and nothing blocking the airflow
on th
If you really want to throw a monkey wrench into the mix, bring up
partial shading...
Or, maybe that's just not allowed in that debate ??Just a thought.
boB
On 11/29/2011 8:39 PM, Kent Osterberg wrote:
Kirk,
You've got some good feedback on this from Ray and Bill. I'll try to
a
on spacing between roof and module. I add 15 deg C for
most situations.
Best I can do from memory.
DT
*From:* Kirk Herander
*To:* RE-wrenches
*Sent:* Tuesday, November 29, 2011 1:48 PM
*Subject:* [RE-wrenches] calculating low string voltage
I am in debate with a PE over calculation of low
/29/2011 2:07 PM, Darryl Thayer wrote:
>>>
>>>
>>> I am on road so I have no texts with me, but the same formula applies about
>>> 0.4% per degree (less voltage) or use the module label voltage coefficent.
>>> However you must
: Re: [RE-wrenches] calculating low string voltage
If you really want to throw a monkey wrench into the mix, bring up partial
shading...
Or, maybe that's just not allowed in that debate ??Just a thought.
boB
On 11/29/2011 8:39 PM, Kent Osterberg wrote:
Kirk,
You'v
, November 29, 2011 10:02 PM
Subject: Re: [RE-wrenches] calculating low string voltage
If you really want to throw a monkey wrench into the mix, bring up partial
shading...
Or, maybe that's just not allowed in that debate ??Just a thought.
boB
On 11/29/2011 8:39 PM,
Member
NYSERDA-eligible Installer
VT RE Incentive Program Partner
*From:*re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of
*b...@midnitesolar.com
*Sent:* Wednesday, November 30, 2011 1:03 AM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenche
Partner
*From:*re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of
*b...@midnitesolar.com
*Sent:* Wednesday, November 30, 2011 1:03 AM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] calculating low string voltage
If you really want to
nt:* Wednesday, November 30, 2011 1:03 AM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] calculating low string voltage
If you really want to throw a monkey wrench into the mix, bring up
partial shading...
Or, maybe that's just not allowed in that debate ?? Just a thought.
boB
...@lists.re-wrenches.org] On Behalf Of Ray Walters
Sent: Thursday, December 01, 2011 3:49 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] calculating low string voltage
That's more detailed info, but I still am wondering what ambient temp to
apply (which AHSRAE #) with the temp adder. Daryl suggested
...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of
*b...@midnitesolar.com
*Sent:* Wednesday, November 30, 2011 1:03 AM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] calculating low string voltage
If you really want to throw a monkey wrench into the mix, bring up
par
ree thanks to
SolarABCs.
Bill.
From: re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Ray Walters
Sent: Thursday, December 01, 2011 3:58 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] calculating low string voltage
Fantastic Info everyon
will absorb reflected light on the backside, so I
>>>>>> assume the cells will operate at a higher temp. But they are elevated
>>>>>> enough to simulate a pole-mount, thus lowering operating cell temp. So
>>>>>> what operating temp
ches-boun...@lists.re-wrenches.org] *On Behalf Of *Ray
Walters
*Sent:* Thursday, December 01, 2011 3:58 PM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] calculating low string voltage
Fantastic Info everyone, I think I've got a full grasp on this topic
now, from using the correct coefficient to the
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