PV north facing in US [RE-wrenches]

[Tom Lane, Energy Conservation Services]

above 30 degrees latitude a roof with a 6/12 pitch will generate almost
nothing from October 21 to February 21 if the array is flush to the roof
facing north  gator tom
----- Original Message ----- 
From: "matthew tritt" <solarone at charter.net>
To: <RE-wrenches at topica.com>
Sent: Tuesday, July 22, 2003 7:12 PM
Subject: Re: PV north facing in US [RE-wrenches]


> Bill,
>
> Egad. Does the CEC recognize a North-facing system as viable for the
> rebates? I just declined a job precisely because of a bank of trees right
> behind the house (South). If the production is 25% less than South the
> payback should take 25% longer, yes?
>
> Since the break-even point is already at 10 yrs + (with rebates) for a
> system that actually is where it's supposed to be, I can see this as a
major
> deterrent for buyers who care about the "bottom line". Will other wrenches
> find this kind of installation so amusing that they assume it was done by
> someone fro Home Depot? ;-)
>
> Matt T
> ----- Original Message ----- 
> From: "Bill Brooks" <billb at endecon.com>
> To: <RE-wrenches at topica.com>
> Sent: Tuesday, July 22, 2003 3:41 PM
> Subject: RE: PV north facing in US [RE-wrenches]
>
>
> Bill and Joel,
>
> My SPAM filter caught this because it said north facing PV in the US (not
> really). However, Joel asks a good question and there is very good answer.
>
> Case in point. A homeowner has a south-facing house with a 4:12 roof pitch
> (18 degrees). The detailed version of Clean-Power Estimator works for a
> North facing array. In Vacaville (Northern California) the north roof face
> will produce 75% of the south face on an annual basis. Now consider a
short
> and fat tree on the south side that provides lovely shade to the house and
> south roof, but leaves the north roof unshaded. The Pathfinder shows that
> the tree limits performance by 40% on an annual basis.
>
> Question: Which location will produce more energy?
> Answer: North face (and we're not in New Zealand!)
>
> Of course system performance could be improved by going flat or tilted on
> tilt legs to the south, but the owner may think that is ugly (and they
would
> be right).
>
> As long as you and the customer know the impact of the decision, go for
it.
>
> Bill.
>
>
> -----Original Message-----
> From: Bill Roush [mailto:solarguide at everestkc.net]
> Sent: Tuesday, July 22, 2003 1:50 PM
> To: RE-wrenches at topica.com
> Subject: RE: PV north facing in US [RE-wrenches]
>
>
> Why North facing? I will never speak ill of a client, they are so rare
> in these parts, so my lips are sealed.
>
> Best,
> Bill Roush
> Solar Electric Systems/KC, Inc.
>
>
>
>
> -----Original Message-----
> From: Joel Davidson [mailto:joeldavidson at earthlink.net]
> Sent: Monday, July 21, 2003 9:17 PM
> To: RE-wrenches at topica.com
> Subject: Re: PV north facing in US [RE-wrenches]
>
> Bill,
> You can input north-facing azimuths in PVWATTS
> http://rredc.nrel.gov/solar/codes_algs/PVWATTS/version1/text_only.html
> I've heard about north-facing arrays in Hawaii because the islands are
> so
> close to the equator and I saw a grid-connected 25 kW array in India
> that is
> manually tilted north and south depending on the season. But PV on a
> north-facing roof in the U.S.? Why?
> Best,
> Joel Davidson
>
> Bill Roush wrote:
>
> > I am not finding the references I see periodically to de-rating for a
> > north facing roof in the US. Any links for me?
> >
> > Best,
> > Bill Roush
> >
> >
> >
> >
> >
>
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