[RE-wrenches] smart mount racking

Jeff Blick jeff.blick at sunlightsolar.com
Fri Oct 31 12:35:20 PDT 2008


Hi wrenches,
Have any of you all installed the smart mount system for panel racking?
Smart mount is a penetrationless racking system that is sold by Sunpower.
We are thinking of using it, though we wonder how it has proven itself in
the real world.  Thanks for your expertise and advice everyone......

 
 
Jeff Blick
PV installer
Sunlight Solar Inc.
4 NW Franklin
Bend, OR 97701
direct: 541-306-4196
fax: 541-322-1911
jeff.blick at sunlightsolar.com
www.sunlightsolar.com
 
-----Original Message-----
From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of
re-wrenches-request at lists.re-wrenches.org
Sent: Friday, October 31, 2008 11:39 AM
To: re-wrenches at lists.re-wrenches.org
Subject: RE-wrenches Digest, Vol 1, Issue 258

Send RE-wrenches mailing list submissions to
	re-wrenches at lists.re-wrenches.org

To subscribe or unsubscribe via the World Wide Web, visit
	
http://lists.re-wrenches.org/listinfo.cgi/re-wrenches-re-wrenches.org
or, via email, send a message with subject or body 'help' to
	re-wrenches-request at lists.re-wrenches.org

You can reach the person managing the list at
	re-wrenches-owner at lists.re-wrenches.org

When replying, please edit your Subject line so it is more specific
than "Re: Contents of RE-wrenches digest..."


When responding to posts within the Digest, be sure to restore the Subject:
line to the original, and please edit out any extraneous lines from the
quoted message.
 

Today's Topics:

   1. Request for signage, disconnect, other safety photos (Dan Fink)
   2. Re: Trouble Shooting Bad Diode (Bill Brooks)
   3. Re: mix-n-match Unisolar (Bill Brooks)


----------------------------------------------------------------------

Message: 1
Date: Fri, 31 Oct 2008 12:22:20 -0600
From: Dan Fink <danbob at hughes.net>
Subject: [RE-wrenches] Request for signage, disconnect, other safety
	photos
To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
Message-ID: <490B4CDC.6080302 at hughes.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Hi all. In addition to being a solar and wind system consultant and 
author, I'm an officer on a volunteer fire department in a remote area 
of the Northern Colorado mountains. About 5 percent of the residences in 
our response area are off-grid, though the gridless area comprises over 
75% of the district. We are a classic "urban interface" department, both 
wildland and structural.

I'm working on a short powerpoint presentation about renewable energy 
systems to give at meetings of other local urban-interface fire 
departments, and likely make available free on the internet. I'm the 
only responder on our department who lives off-grid, and most 
firefighters don't realize the special issues with off-grid systems.

They expect that when you swing your axe and chop the mains off from the 
powerline (or, preferably, throw the switch, but that's not always 
possible), all circuits in the home, outbuildings and property are dead. 
This is not the case with islanding systems, nor with solar arrays and 
wind turbines using non-islanding grid-tie. And now that we commonly 
wire PV and wind at voltages over 100v, it could be hazardous to the 
firefighter that was not informed. Other aspects of the presentation 
include wind turbine tower guy wires and their anchors that are 
vulnerable to weakening from vegetation burning under them, the hazards 
of battery banks, various ways well pumps might be connected (nice to 
have water at the scene), and more.

Please contact me off list if you have any photos you would be willing 
to share, with credit and copyright notice to you. Images of signage, 
interesting system disconnects (not everyone has a factory-built power 
panel) and their labeling, anything that might relate to firefighter 
safety, would be much appreciated.

DAN FINK
Technical Director
http://www.otherpower.com/

Rist Canyon Volunteer Fire Department
http://rcvfd.org/

KC0VRD
WQGS890





------------------------------

Message: 2
Date: Fri, 31 Oct 2008 11:33:51 -0700
From: "Bill Brooks" <billbrooks7 at yahoo.com>
Subject: Re: [RE-wrenches] Trouble Shooting Bad Diode
To: "'RE-wrenches'" <re-wrenches at lists.re-wrenches.org>
Message-ID: <000801c93b87$39cefce0$ad6cf6a0$@com>
Content-Type: text/plain; charset="us-ascii"

Kirpal,

 

When you parallel, your voltages have to be the same, so you are correct in
that assumption.

 

Your assumption about the diodes is not correct. Diodes don't work like
that. You could have a shorted module (all three diodes shorted) which would
lower the Voc by one module. It looks like you have nearly two modules worth
of problems. It could be a total of 5 bad diodes, but that would be weird.
It could be you have a ground fault, and haven't tripped the GFP yet because
of lower sunlight levels-(it has to be very low sun to stay under 1 amp).
You also could have a wiring mistake, either because the factory reversed
wired a module (rare, but it happens)-that would be 2 modules low; or, you
could have skipped two modules somehow.

 

It does seem like a quarter of the bad string is out. Your assumption about
bad diodes could be correct, but it only affects the groups of cells its
connected to. Each diode protects 24 cells-it looks like you have 5 diodes
worth of loss. It could be in 2 modules, or up to 5 modules. 

 

The shading test is the best way to find bad diodes. Disconnect the bad
string from the good one and take a piece of cardboard the dimension of the
module. With your meter testing Voc on the back string, completely cover
each module, one at a time. When the Voc is not affected by complete shading
of a module, that module is completely bad. If the shaded module only loses
a portion of one module's Voc, then you have one or two, of the three
diodes, bad.

 

This is a great opportunity to learn how to troubleshoot a PV array. Take
the time, and the effort, to run through it carefully, learn the problems,
and report back with your findings. It's a beautiful thing to learn
something new.

 

Bill.

 

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Kirpal
Khalsa
Sent: Friday, October 31, 2008 10:43 AM
To: RE-wrenches
Subject: [RE-wrenches] Trouble Shooting Bad Diode

 

Greetings all......I was hoping i could have someone help me confirm a
troubled series string on a system we have installed.....
System consists of 16 BP 170 W 24V nominal modules......2 strings of 8
modules.....Vmp of each module is roughly 34V and Voc of each module is
roughly 41V.  One string is under-producing......String 1 Voc is 346V and
String 2 Voc is 272V.  String 1 Vmp under load is 270V and String 2 Vmp
underload is 270V.  I am hypothesizing that String 2 has a bad diode on the
3rd panel in and is reducing the Voc of that string by th 2 panels ahead of
it in the string.  I am hoping to figure this out without removing the
entire string and checking each panel if possible.....
I think the Vmp is equal due to the fact that both strings are paralleled in
the inverter and the 1st string is being pulled to the same level V as the
2nd string under load......Is my logic good?
Thanks for the help and advice.....
Cheers,
Kirpal Khalsa
Renewable Energy Sytems

-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachme
nts/20081031/ded40350/attachment-0001.htm>

------------------------------

Message: 3
Date: Fri, 31 Oct 2008 11:38:55 -0700
From: "Bill Brooks" <billbrooks7 at yahoo.com>
Subject: Re: [RE-wrenches] mix-n-match Unisolar
To: "'RE-wrenches'" <re-wrenches at lists.re-wrenches.org>
Message-ID: <001201c93b87$ef0c3c30$cd24b490$@com>
Content-Type: text/plain; charset="us-ascii"

Geoff,

 

The ultimate issue is how many cells are in each series string and is the
voltage of the cells nearly the same. As long as the number and the voltage
of the cells match up for each string, it makes no difference what
arrangement the modules are in.

 

You could have 5 + 6 + 7 = 18 cells in one group and 3+10+5 =18 cells in
another group, and its all good as long as they are similar cells. Unisolar,
due to the low fill factor, is actually pretty forgiving of difference
modules and cells. If you need help, let me know.

 

Bill.

 

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Jason
Lombard
Sent: Friday, October 31, 2008 8:55 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] mix-n-match Unisolar

 

You are correct and they are not. The entire string or array will drop the
lowest performing panel and seriously detain performance.

On Thu, Oct 30, 2008 at 2:29 PM, Geoff Greenfield <geoff at third-sun.com>
wrote:

I thought I knew the answer to this one, but wanted to run it by the list.

 

We are responding to a bid where the electrical engineer has designed a
system with different sized Uni-solar laminates in some series strings
paralelled with consistant full size strings.  (this was done to work around
skylights etc).

 

We suggested that this was a poor design and will lead to "least common
denomenator" performance, exacerbated by MPPT confusion.  The EE responded
that "the bypass diodes allow for this".

 

Any experience with this in practice?

For a brighter energy future,

Geoff Greenfield
Founder and CEO
Third Sun Solar & Wind Power Ltd.
340 West State Street, Unit 25
Athens, OH 45701

740.597.3111     Fax 740.597.1548
www.Third-Sun.com

Clean Energy - Expertly Installed




_______________________________________________
List sponsored by Home Power magazine

List Address: RE-wrenches at lists.re-wrenches.org

Options & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org

List-Archive:
http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org

List rules & etiquette:
www.re-wrenches.org/etiquette.htm

Check out participant bios:
www.members.re-wrenches.org






-- 
Jason Lombard
Open Hand Solar LLC.
HC74 Box13
Pecos, NM. 87552
505 795 8646

-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachme
nts/20081031/9428693d/attachment.htm>

------------------------------

_______________________________________________
List sponsored by Home Power magazine

List Address: RE-wrenches at lists.re-wrenches.org

Options & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org

List-Archive:
http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org

List rules & etiquette:
www.re-wrenches.org/etiquette.htm

Check out participant bios:
www.members.re-wrenches.org



End of RE-wrenches Digest, Vol 1, Issue 258
*******************************************




More information about the RE-wrenches mailing list