[RE-wrenches] Positive-ground question re Sunpower

[boB Gudgel]

On 11/19/2010 5:22 PM, Glenn Burt wrote:
>
> It has been my experience that if Sunpower modules are installed 
> contrary to their manufacturer recommended positive ground 
> configuration, that in a short time you will only be generating a few 
> watts. I have seen this in more than one instance when the array was 
> mis-wired and the negative was the grounded conductor.
>
> Fortunately reversing the wiring allows the static charge to bleed of 
> in a couple of weeks, and the strings returned to their expected 
> production values.
>
> I would recommend against trying to use them intentionally in this 
> fashion.
>
> -Glenn
>




If you have Sunpower modules that are raised up in the air, what if you 
put a conductive
plate on the back side of the PV module and tie that to positive ??   
(like a Faraday shield)

Does that accomplish the same thing ?   If not, and if you take it 
literally that the
positive must be attached to "earth ground", then I guess this would 
keep Sun Power out
of the solar powered airplane (or space) business.

I  asked Sun Power this question at SPI a couple of years ago and nobody 
could
give me any kind of answer.

boB







> *From:*re-wrenches-bounces at lists.re-wrenches.org 
> [mailto:re-wrenches-bounces at lists.re-wrenches.org] *On Behalf Of 
> *Allan Sindelar
> *Sent:* Friday, November 19, 2010 10:08 AM
> *To:* RE-wrenches
> *Subject:* [RE-wrenches] Positive-ground question re Sunpower
>
> Wrenches:
> This has been addressed before in a slightly different context, so a 
> short answer is enough. Can a Sunpower module be used successfully in 
> a negative-grounded low-voltage system?
>
> The situation: Mark in our Taos office sent me the following: "We have 
> an old time friend and customer. [John] and his wife used to help us 
> on various installations years ago. They're both retired now and 
> living on fixed limited income. About two months ago, we sold them a 
> replacement battery bank of golf carts. They have a  small off grid 
> system with a few hundred watts of PV. Recently, [John's wife] was put 
> on an oxygen machine for a heart condition. The machine consumes 
> somewhere around 800 Watt-hours per day. Their system can't keep up 
> now without running the generator most every day. I was wondering 
> about a couple blem/cosmetic damaged panels that PosE has at their 
> shop in Santa Fe. I'm not sure yet whether the best solution would be 
> to upgrade their existing system, or perhaps a separate system for the 
> O2 machine. Either way, if there is a way to help them with the 
> equipment, then I'd be happy to donate my time to help [John] do an 
> upgrade. If there is some way we can help them out, it would be a good 
> thing. They're just a couple of really good people who've helped a lot 
> of others out in their lifetime. Now they're the ones in need, and I'm 
> just trying to find a way to help them."
>
> We have two Sunpower 215s with cosmetic damage that can't be sold. I 
> think that one or both can be used here, but are just somewhat less 
> efficient if negative grounded.
>
> What's the straight scoop here, please?
> Thanks,
> Allan
>
> Allan at positiveenergysolar.com <mailto:Allan at positiveenergysolar.com>
> NABCEP Certified Photovoltaic Installer
> EE98J Journeyman Electrician
> *Positive Energy, Inc.*
> 3201 Calle Marie
> Santa Fe, New Mexico 87507
> *505 424-1112*
> www.positiveenergysolar.com <http://www.positiveenergysolar.com/>
>
>

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