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" <d...@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-boun...@lists.re-wrenches.org > [mailto:re-wrenches-boun...@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 <dahlso...@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 >> _______________________________________________ >> List sponsored by Home Power magazine >> >> List Address: RE-wrenches@lists.re-wrenches.org >> >> Change email address & settings: >> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >> >> List-Archive: > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >> >> List rules & etiquette: >> www.re-wrenches.org/etiquette.htm >> >> Check out participant bios: >> www.members.re-wrenches.org > _______________________________________________ > List sponsored by Home Power magazine > > List Address: RE-wrenches@lists.re-wrenches.org > > Change email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out participant bios: > www.members.re-wrenches.org > > > _______________________________________________ > List sponsored by Home Power magazine > > List Address: RE-wrenches@lists.re-wrenches.org > > Change email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out participant bios: > www.members.re-wrenches.org > _______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Change email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org