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

[Geoff Greenfield]

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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