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-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@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
al...@positiveenergysolar.com <mailto:al...@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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