Unisolar standing seam roofs [RE-wrenches]

[Doug Pratt]

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Jeff,
Uni-Solar PVL laminates on a copper roof is NOT recommended! There will be no factory warranty, only a one-year materials and workmanship warranty. 

I say this as the main tech support person at Uni-Solar's primary North American distributor. 

All Uni-Solar products are built on a galvalume sheet metal base. That's why they insist on the peel 'n stick laminates being applied to only galvalume roofs. Same expansion and contraction rates between the roof and the laminate, therefore, they stay stuck and you get a 20 year performance and adhesion warranty.

On copper there will be a different expansion/contraction coefficient and some chance that the laminate may eventually develop buckles or blisters.

If your client absolutely insists on using the PVL laminates you can stick them to a flat strip of standard galvalume roofing metal, and then work with a roofer to attach that assembly to the copper in a manner that isn't going to leak, buckle, or blow off. Uni-Solar will (and has) given full warranties for installations like this. 

Figure about 5.5 watts per square foot for the Uni-Solar PVL material. It's all 15.5" wide, and currently available in 9'6" lengths (68 watts), 14'6" lengths (124 watts), and 18'0" lengths (136 watts). For 12 kW you need a minimum of 2,200 sf, probably more, unless available lengths fall perfectly.

Good luck...
Doug Pratt
DC Power Systems


-----Original Message-----
From: Jeff Yago [mailto:jryago at netscape.com] 
Sent: Saturday, June 09, 2007 9:30 PM
To: RE-wrenches at topica.com
Subject: Re: Unisolar standing seam roofs [RE-wrenches]


I have spent several weeks designing a 12 kW grid tie system that includes a large battery back-up system for a client who will not consider a generator to allow using a smaller battery system.  After lots of meetings with the local power company to work out their inter-connect requirements and sizing all the equipment, the client just informed me that he saw an installation somewhere that used the Unisolar strip modules and he now wants to use these on his standing seam copper roof.   I tried to advise him that he does not have the roof area for thin-film which is why we were designing around a large ground mount system using 160 watt framed modules (hobby farm with lots of land).

I do not want to bad mouth this product.  I know they have really improved performance with the triple-junction design and I agree there are many applications where the Unisolar might be the better choice.   But with his desire for a very large array with battery backup (48 to 72 volt array strings), limited roof area, and very long life, I feel this is the wrong application.

Any of you had good experience with these modules bonded to a standing seam copper roof and low voltage strings for array size above 10 kW?

Since I will be getting out of this project if he insists on us switching to the Unisolar thin-film modules, anybody interested in taking over this client located in central Virginia using the Unisolar he demands?? 

Thanks,

Jeff Yago

_____________________________________________________________
Netscape.  Just the Net You Need.


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