[RE-wrenches] SE or SW

[Benn At DayStarSolar]

Thanks for pointing that out Dave. 
PVWatts is a great tool but you're right, unfortunately it doesn't account for snow cover. 

It's best to go into the derate settings and using your knowledge of the different site/equipment factors, adjust accordingly. 

benn
Sent from a 'smart' phone, with touch screen keys. Please excuse shortcuts and typos. 

On 2013-05-14, at 6:18 PM, "Dave Palumbo" <dave at independentpowerllc.com> wrote:

> PV Watts does not consider snow. So, if you are in an area that snow
> coverage is an issue then you have become the decider based on what your
> best instincts and your experience tell you. I've got some second story (not
> workable for a roof rake unfortunately) low sloped roofs for clients that
> can stay snow covered for weeks at a time. But I know that going in and I
> take PV watts and de-rate the 5 months that we get significant snow here in
> northern Vermont and no one is surprised and disappointed with the poor
> winter production.
> 
> Dave Palumbo
> 
> -----Original Message-----
> From: re-wrenches-bounces at lists.re-wrenches.org
> [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Benn At
> DayStarSolar
> Sent: Tuesday, May 14, 2013 7:10 PM
> To: RE-wrenches
> Subject: Re: [RE-wrenches] SE or SW
> 
> Jesse,
> A good decision can be based on, among other site/load specific details, the
> site's "micro-climate". 
> 
> Do they tend to have clear mornings and cloudier afternoons/evenings? 
> ...or cloudy/foggy mornings and clearer afternoons/evenings?
> 
> Maybe throw the different directions into PVWatts and see what it says,
> since it is based on weather history (isn't it?)
> 
> Good luck. 
> benn
> Sent from a 'smart' phone, with touch screen keys. Please excuse shortcuts
> and typos. 
> 
> On 2013-05-14, at 4:34 PM, Jesse Dahl <dahlsolar at gmail.com> wrote:
> 
>> Hello,
>> 
>> I was asked to look at a site today for a homeowner looking for a grid-tie
> with battery-back up. They are Doomsday Preppers for lack of a better term
> and want certain loads if and when the grid goes down for good. Aside from
> parts selection, they have two roof lines, one facing SE one facing SW. the
> SW is very low slope and is only accessible with a ladder and climbing on
> the roof, the other is SE, much steeper slope and accessible from the ground
> or deck.  I mention the access because of snow removal. We had lots of snow
> last year and I spent lots of time on my roof removing 8" snow falls.  Both
> have good solar access.  
>> 
>> I'm inclined to chose the SE roof line, but I am interested in arguments
> for the SW. 
>> 
>> Thanks!
>> 
>> Jesse 
>> 
>> Sent from my iPhone
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