PV north facing in US [RE-wrenches]

[Joel Davidson]

If they really want to make the world a better place with PV, perhaps they
would like to donate a few PV systems to people in developing countries who
have good solar access but no electricity and no subsidies.

Bill Roush wrote:

> Just to further clutter up the debate I started, keep in mind that coal
> plants aren't often placed for maximum efficient power delivery to the
> consumer either, as they are located many miles and transmission
> efficiency percentage points away from their end users. There are many
> more examples we could site. This customer probably won't buy anything
> here in the land of NO subsidies anyway, and if they do they will be
> told what to expect of the systems production. I'll be lucky if they go
> with a 'token' solar installation. If they still want to spend their
> money that way, they are free to do so in the land of the free and the
> home of the brave. I would still rather have people 'waste' money on a
> good, but less than perfect solar installation than most of the things I
> see money 'wasted' on.
>
> Best,
> Bill Roush
> Solar Electric Systems/KC, Inc.
>
>
>
> -----Original Message-----
> From: Bill Brooks [mailto:billb at endecon.com]
> Sent: Wednesday, July 23, 2003 11:51 PM
> To: RE-wrenches at topica.com
> Subject: RE: PV north facing in US [RE-wrenches]
>
> Graham,
>
> The thermal efficiency of a thermal collector goes to pot at low
> irradiance
> depending if the ambient temperature is low so there is some difference
> to
> the response of PV vs. Thermal at low irradiance. Off-angle irradiance
> would
> have a greater effect on a thermal collector and I think that is born
> out in
> the incident angle modifiers that are used in the performance models for
> each.
>
> To develop a valid performance model you have to take into account
> irradiance, temperature, and incident angle modifier to get the answer.
> You
> also must validate that information against a real world installation.
> There
> are some very well validated models out there that do this stuff.
>
> There are a lot more people that use various computer models without a
> full
> understanding of how they work (e.g. PVWATTS) and end up with ridiculous
> results. Garbage in is, in fact, garbage out.
>
> Mounting collectors on the north side of a very low pitch roof would
> admittedly be a last resort, but I can't say that I would never do it. I
> have seen plenty of people install systems that perform below 75% of
> optimal
> (like about half the systems in California if the truth were known). It
> does
> not justify bad performance, but many installations have far worse
> performance than expected for a variety of reasons. The pictures you
> posted
> on your website are an excellent case in point.
>
> The desire of that installer to get better performance by facing the
> panels
> to the south had a much worse effect than laying them in the roof
> orientation--but the installer clearly had no idea--that's the scary
> part
> and why I will continue to teach basic PV courses to neophytes.
>
> Bill.
>
> -----Original Message-----
> From: Graham Owen [mailto:graham at solarexpert.com]
> Sent: Wednesday, July 23, 2003 5:41 PM
> To: RE-wrenches at topica.com
> Subject: RE: PV north facing in US [RE-wrenches]
>
> Hi Doug, The street name was changed in Photoshop.
>
> I would NEVER install a solar panel facing north in So Cal.  If you look
> at the performance of solar water heaters on tract homes the water in
> the north facing systems will be approximately the same as ambient, when
> the south facing systems are HOT.  Maybe the photon absorption on PV
> modules is completely different than thermal collectors, but as a solar
> guy it seems wrong to install solar panels facing north.  Am I wrong?
>
> Graham
>
> -----Original Message-----
> From: Doug Pratt [mailto:dmpratt at sbcglobal.net]
> Sent: Wednesday, July 23, 2003 5:27 PM
> To: RE-wrenches at topica.com
> Subject: RE: PV north facing in US [RE-wrenches]
>
> Is this wonderful example REALLY on "Total Eclipse Dr.", or did someone
> Photoshop in that street sign?  Too cute... -Doug
>
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