[RE-wrenches] Solar Ready remodel

[Peter Parrish]

Hello Holt: 

 

First make sure you estimate your time and materials and get paid 100% for
the work you do. In other words don’t count on any follow on work. Then,

 

(a) Figure out where the inverter is going to go. Plan for the inverter,
disco, production meter, subpanel (if any).

 

(b) Stub out a ¾” (or 1”) nipple at the appropriate point on the wall, put a
pull box in the wall space.

 

(c) From the pull box, run either metal flex (empty flexible metal conduit)
or MC cable (prewired cable) to the attic and the point of roof penetration.

 

(d) Penetrate the roof and put another pull box and nipple (or appropriate
length of rigid conduit) at this point; and of course do a good job of
flashing in the penetration.

 

(e) If you used MC cable, strip enough of the clad off to leave ample wire
at both ends for what you want to do there.

 

(f) Mark the cable/conduit run with peel and stick labels that say “Solar”
or “Danger Solar” or “Danger Solar 600 Vdc). I am pretty generous with these
labels, using them every 10’ on long runs in the attic and every 6’ in
walls.

 

(g) You will also need to provide a means of disconnection on the roof
before penetration. You can use a DC-rated disconnect (my choice) but I have
heard that “touch-safe” fuses or circuit breakers serve as adequate means of
disconnection. Does anyone else know something definitive? If you use a
disco, you should NOT need to provide over-current protection if you size
you wire according to code and have a letter from the inverter manufacturer
stating that the inverter cannot back-feed the PV array. 

 

Personally, I like MC cable, as it comes pre-wired with 2 current carrying
conductors plus a ground (e.g. MC10-2, for AWG-10) or 4 current carrying
conductors plus a ground (e.g. MC10-4 for AWG-10). Since it is pre-wired,
the resulting diameters are impressively small. There are special connectors
for MC. There seems to be a distinction between MC being cable and MF being
a raceway, and possibly MC cable not being allowed by the AHJ. I get
pre-approval for MC before I start from the planning department, use the
protection plates wherever an errant nail or sheet rock screw could do
damage, and use lots of labels. Inspectors are usually impressed with these
pre-cautions and I have never had a problem.

 

Oh, two other things. When I do use MF, I like to pre-wire it using a long
level space (like a driveway). It a whole lot easier to pull the wire than
after it is in place. I guess that there is a limit to the number of bends
one can make in MF before putting in a pull box (it’s conduit after all).  

 

Good luck.

 

- Peter

Peter T. Parrish, Ph.D., President
California Solar Engineering, Inc.
820 Cynthia Ave., Los Angeles, CA 90065
Ph 323-258-8883, Mobile 323-839-6108, Fax 323-258-8885
CA Lic. 854779, NABCEP Cert. 031806-26
peter.parrish at calsolareng.com 

  _____  

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of
holtek at sbcglobal.net
Sent: Saturday, February 07, 2009 7:35 AM
To: RE-wrenches
Subject: [RE-wrenches] Solar Ready remodel

 

Wrenches,

I am working with a client that is doing major remodeling on a recently
purchased house. His budget is not allowing PV at this time, but he is very
serious about adding it when he sells other property. I am suggesting that
we make the house "solar ready" for such a time. I'm thinking to run
oversized conduit to dedicated solar equipment room making wire runs easier
when that time comes around. It is unclear as to the size of system budget
will allow at future date (roof will accomodate approx. 9kw). Are there any
further steps  that are suggested while the walls are open to make a future
install as economical as possible? 

 

 

Holt E. Kelly
Holtek Fireplace & Solar Products
500 Jewell Dr.
Waco TX. 76712
254-751-9111
www.holteksolar.com

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