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#167230 - 08/08/07 10:05 AM "wiring solar panels for residential"
sparkync Offline
Member

Registered: 10/17/02
Posts: 811
Loc: NC
Anyone had any experience in wiring solar panels for residential houses? I have a potential job of wiring them and wanted to see if "anything special" I should know. The job is going to be about 50 or 60 miles from me, and thought I would find out as much as possible before getting in contact with the customer. I would think it would be pretty standard; power supply, disconnects etc. etc.... but want to make sure......Thanks for the help. Steve....

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#167234 - 08/08/07 10:26 AM Re: "wiring solar panels for residential" [Re: sparkync]
earlydean Offline
Member

Registered: 12/22/03
Posts: 749
Loc: Griswold, CT, USA
Check out this webpage:

http://www.nmsu.edu/~tdi/Photovoltaics/Codes-Stds/Codes-Stds.html

Download and print out the booklet:

Photovoltaic Power Systems and the 2005 National Electrical Code: Suggested Practices
written by John Wiles and published by Sandia National Laboratories

and the checklist.
_________________________
Earl

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#167280 - 08/09/07 07:17 AM Re: "wiring solar panels for residential" [Re: earlydean]
sabrown Offline
Member

Registered: 12/12/02
Posts: 297
Loc: Ogden, Utah, USA
I recommend the above also. Taking note of the following:

GFI (equipment not GFCI) requirements for residential roof (I would include building, but that is my opinion) mounted panels (typically about $300-500 for DC, NEC 690.5) (AC requirements NEC 690.6(D)).

Interconnection/disconnect requirements with the POCO (NEC 705.40).

Finding DC rated switches for DC lighting (no standard toggles anymore that I can find - have to go to rocker switches minimum order of 50 and route out holes in blank plates)(several mfg of rocker switches also do not have DC rated switches).

Shane

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#167287 - 08/09/07 11:02 AM Re: "wiring solar panels for residential" [Re: sabrown]
EV607797 Offline
Member

Registered: 10/25/06
Posts: 756
Loc: Fredericksburg, VA, USA
Maybe I haven't been paying as much attention to this as I should have been. I do remember switches having DC current ratings years ago and never gave this much thought.

Anyway, I was under the impression that most modern solar installations involve inverters and battery banks. Is this not the case?

I still don't see how these systems can provide enough power for today's typical US home. Sure, gas can be used for heating, air conditioning, cooking and hot water, but doesn't that kind of defeat the purpose?
_________________________
---Ed---

"But the guy at Home Depot said it would work."

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#167288 - 08/09/07 12:35 PM Re: "wiring solar panels for residential" [Re: sabrown]
LK Offline

Member

Registered: 01/21/03
Posts: 1721
Loc: New Jersey
 Originally Posted By: sabrown
I recommend the above also. Taking note of the following:

Finding DC rated switches for DC lighting (no standard toggles anymore that I can find - have to go to rocker switches minimum order of 50 and route out holes in blank plates)(several mfg of rocker switches also do not have DC rated switches).

Shane


Why would you need DC rated switches?

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#167298 - 08/09/07 05:23 PM Re: "wiring solar panels for residential" [Re: LK]
sparkync Offline
Member

Registered: 10/17/02
Posts: 811
Loc: NC
Wow!!! Unless I find some simplier explanations, I better pass this job up. Thanks... Steve...

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#167301 - 08/09/07 08:24 PM Re: "wiring solar panels for residential" [Re: sparkync]
gfretwell Offline

Member

Registered: 07/20/04
Posts: 9045
Loc: Estero,Fl,usa
LK DC switches have better interrupting capability. You don't get the help of a zero crossing to put the fire out.
_________________________
Greg Fretwell

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#167315 - 08/10/07 07:35 AM Re: "wiring solar panels for residential" [Re: EV607797]
BrianP Offline
Member

Registered: 02/01/07
Posts: 65
Loc: Minnesota
 Originally Posted By: EV607797
I still don't see how these systems can provide enough power for today's typical US home.


Is this an "off-the-grid" installation? If not, then it doesn't have to supply all the power, as the POCO will provide the rest. Typically, the POCO also buys back excess power during peak generation times.

If it is off the grid (no POCO connection), I think it is generally done with lots of power conservation (ultra-efficient lighting and appliances along with lifestyle adjustments to reduce energy use even more). Heating and hot water may be provided by a separate solar system.

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#167329 - 08/10/07 09:51 AM Re: "wiring solar panels for residential" [Re: BrianP]
gfretwell Offline

Member

Registered: 07/20/04
Posts: 9045
Loc: Estero,Fl,usa
There are still some off grid folks around here. They use fossil fuels for heating stuff (cooking etc) You can have all the hot water you want from the sun most of the time. That is actually the only thing that really makes sense financially since it is fairly cheap to install and low maintenance.
Anyone with a PV system is either off grid or off on a crusade of some sort. I doubt anyone ever saved a dime if they are honest in their accounting.
_________________________
Greg Fretwell

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#167331 - 08/10/07 11:17 AM Re: "wiring solar panels for residential" [Re: gfretwell]
SolarPowered Offline
Member

Registered: 07/05/04
Posts: 615
Loc: Palo Alto, CA, USA
Greg,

Home Power magazine a couple months ago featured a grid-tie system located in Canada. As I recall, this system cost $15,000 Loonies, and offset all of $5 Loonies a month in power. They were very proud of how they offset all of their electrical requirements (zero annual bill) though extreme measures of installing low-power everything.

They had originally figured that the "system would pay for itself" in a few years. After the fact, they figured it would take longer...


When I figure in some Cost of Funds, it looks like they're losing around $1,500 a year on this thing...

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