[RE-wrenches] ballasted roof rack - on the ground?

Wed Aug 26 13:43:13 PDT 2009

We've done ground mount ballasted systems, but we call them Skid  
mount systems. We build them custom for any project.
Here's a shot of one towards the bottom of this page:  http:// 
www.solarray.com/NewSolarRay/NewSolarRay_T.php
We use the batteries for ballast, but concrete pavers could be  
substituted. The entire system can be lifted off a trailer with a  
forklift and setup in a couple of hours.
I'd be leery of using a standard roof ballast system on the ground:  
both due to dirt build up on the modules, and animals.
One cow gets loose in the area, and they could do 10s of thousands of  
dollars in damage.

R. Walters
Solarray.com
NABCEP # 04170442	

On Aug 20, 2009, at 9:35 PM, Geoff Greenfield wrote:

> esteemed wrenches (or just steamed if youve been out in the hot  
> lately)
>
> I'm curious why more folks don't use the same flat roof ballasted  
> rack approach for large ground mounts?  Geotech weed barier and off  
> we go...  my initial calcs sat its a cost saver... my instinct says  
> it viable, but my other instinct says "if it were this easy I would  
> see it all the time (and I've never seen it)
>
> what's up?  frost heave/instability?  wav-i-ness of the ground?  
> better performance at steep angle worth all the extra cost (not  
> according to my pencil with today's mod costs).  Thoughts?
>
> For a brighter energy future,
>
> Geoff Greenfield
> President
> 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
>
>
>
>
>
>
> ----- "Dave Click" <daveclick at fsec.ucf.edu> wrote:
> > Thanks all.
> >
> > It was my understanding that we should still be running the  
> conductors
> > of the same circuit through the same raceway, even if it is the  
> DC input
> > into the inverter since that DC oscillates slightly (nowhere near as
> > much as AC). I wasn't concerned about eddy currents in the FNMC of
> > course but the metal box itself, a concern being voiced on this list
> > before. I'd be more concerned about this if it were a 1MW inverter
> > rather than a 7kW, but still.
> >
> > Thanks for the info on the GEC tap and I'm glad the split bolts  
> work here.
> >
> > The conduit in question doesn't seem to be there just for physical
> > protection; the wire runs from the east end of the array for  
> 100'+ and
> > only the last 3' are in conduit. If it were only for protection  
> I'd be
> > fine with it being open-ended on both ends, but since it's there  
> to feed
> > the conductors into the box, that's why I was treating it as a  
> regular
> > conduit that required a cord grip at the other end. Where do  
> others make
> > the distinction?
> >
> > Thanks,
> > DKC
> >
> > -------- Original Message --------
> > Subject: Re: [RE-wrenches] DC positive and negative in same conduit,
> > other inspection issues
> > From: Kelly Keilwitz, Whidbey Sun &  Wind <kelly at whidbeysunwind.com>
> > To: RE Wrenches listserve <re-wrenches at lists.re-wrenches.org>
> > Date: 2009/8/19 21:10
> >
> > > Dave,
> > > Only GEC's are subject to the "continuous" rule (250.64C). It  
> sounds like
> > > your are talking about an EGC tapped from the GEC.
> > >
> > > When splicing PV GEC's required under 690.47D, either together  
> (from
> > > separated arrays) or to the existing AC GEC (if close enough),  
> we have been
> > > allowed to use split bolts instead of irreversible splices, per  
> 250.64D1,
> > > "Grounding Electrode Conductor Taps" (at end of paragraph).  
> I.E., the
> > > "continuous" rule is only being applied to the main GEC.
> > >
> > > I agree with Kurt on the LTNMF being used only as extra (not  
> required) wire
> > > protection for the USE-2. We often do this when running PV  
> conductors
> > > between short separations in modules or rails. I would think  
> that only
> > > temperature and fill corrections would apply - and only if the  
> length
> > > requires.
> > >
> > > -Kelly
> > >
> > > Kelly Keilwitz, P.E.
> > > Whidbey Sun & Wind, LLC
> > > Renewable Energy Systems
> > > NABCEP Certified PV Installer
> > > 987 Wanamaker Rd,
> > > Coupeville, WA 98239
> > > PH & FAX 360-678-7131
> > > sunwind at whidbeysunwind.com
> > >
> > > On 8/19/09 2:41 PM, "Dave Click" <daveclick at fsec.ucf.edu> wrote:
> > >
> > >> For the grounding electrode wiring, it seems that it's fine to  
> me since
> > >> they ran the continuous #6 to each rail and then to the rod,  
> qualifying
> > >> as the 690.47(D) supplemental electrode. But the split bolts  
> tapping
> > >> that GEC to "ground the disconnect," these are required to be
> > >> irreversible connections to the ground bus in that disconnect,  
> right?
> > >
> > >
> > >
> > >
> > >
> > >
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