Top Down logistics [RE-wrenches]

Fri Jan 31 12:38:12 PST 2003

William,
Uni-Rac's top-down Solar Mount system is pretty darn workable IMO.  I would
say after looking at the tiletrac stuff at their website, Solar Mounts are
an even faster system.

I detest the dangling MC's too and they just lay there perfectly on the
surface of the shingles, ready to catch whatever flows down the rooftop.
Only thing I can think of is taking a safe drill up there (or at the shop)
and drill a 1/4" hole in the side of module's frame, where the MC's are
going to connect.  Then take some UV black wire ties that will fit through
the hole and tighten it up such that the MC connector tucks up into the
sidewall of the frame.  You can always throw a piece of shrink over the
connection beforehand too.

Recently, we put the long conduit runs underneath the roof and had all the
wire runs come down through two penetrations, two J-boxes on the top of the
roof, collecting 3 and 2 strings.  We exited the attic through the eave
above the inverters.  This saved a lot of ugly gray flex on the roof.

As far as junction box work underneath the modules, MC's will save a lot of
this work but where you have to, it's the same with Uni-Rac's--just loosen
(do not have to remove) four nuts (the bolts stay locked in the rail) and
lift it up.  The bigger modules require two people for this and it's a
difficult reach in most cases.

By the way, does anybody know of a battery powered cordless heat gun?

Peter
ASAP POWER!

-----Original Message-----
From: William Miller [mailto:wrmiller at slonet.org]
Sent: Friday, January 31, 2003 10:45 AM
To: RE-wrenches at topica.com
Subject: Top Down logistics [RE-wrenches]

Graham:

Thanks for the reply.  I sounds like you have not done any top down
installations of larger frame modules yet.  I read yet again the Tile Trac
installation instructions and they gloss over the wiring part of the job,
so that was of no help in answering my questions.  Are any other wrenches
out there doing top down of J-box equipped modules?  How do you wire these
and avoid the pitfalls of conduit laying on the roofing?

I have a system to install soon that will be racked on the DPW Power Rail.
It is 24 SM110 modules shoe horned onto a roof barely large enough.  The
bottom row will be 14 modules across and the top row will be 10.  There is
not enough room to separate the modules into individual tilt up racks for
back access.  I detest MC cables because I can't bring myself to have
connections exposed to the elements and dangling from the backs of modules.
 I plan on using longer inter-panel conduit and jumpers.  Each next module
will be prepared with a conduit and jumper for connecting to the following
module.  It will be laid glass-to-glass with the previous for wiring and
then be flipped into place for installation .  I will attach the extra
conduit to the rail using the slot in the rail to keep the conduit off the
tile.

Series strings require the far end have a connection as well.  I don't want
to run a long lead through every module, so I will run PVC along the rail
to a J-box at the end prior to installing modules.

I'll let you know how it goes.  I look forwards to making this system work
because the rail system may solve some problems, i.e. uniform module
spacing, getting the racking to conform to rafter spacing, etc.

William Miller

At 10:01 AM 1/31/2003 -0800, you wrote:
>Hi William,
>
>I still panelize SP75's in shop for flush mounted roof installs .  Heyco
>Flex conduit between modules and ground each individual module.  For
>ground mounts and racked up systems, with easy rear module access, I
>like the SP140's and I still put conduit between the modules.  When I
>need to access the rear side of flush mounted modules, it is easy to
>undo four bolts and tilt up all four modules.  I prop them up with a
>three foot section of 2x4 and crawl underneath.  I realize this wouldn't
>be so easy on a steep pitch, but luckily I have not had to access the
>back side of any modules (yet) on a steep roof.  The new Shell earthsafe
>HV-100 systems give you the option of MC's or conduit.  I may start
>installing SP140's on sloped roofs one module at a time with top-down
>clamps and MC's.  I have heard that MC's installed on humid days can get
>hot in the summer and open up a little bit. (does anyone have more info
>on this?) I wish the PV manufacturers would make an approved grounding
>point on the narrow end of the modules.  I believe most of the SMUD
>installs are panelized in shop and a crane is used on each job to get
>the panels on the roof.  If prevailing wage becomes required it is
>cheaper to get as much work done in shop as opposed to time on the roof.
>
>Graham
>
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William Miller
Miller Power and Communications
PO Box 50, Santa Margarita, CA 93453
Voice :805-438-5600     Fax: 805-438-4607
email: wrmiller at slonet.org
http://millerpowerandcomm.com
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