I did play around with numbers on there and came to that conclusion. Considering I'm only 50 miles from international falls, it's even a clearer choice then running the numbers in the cites.
Verification is always nice! Jesse Sent from my iPhone On May 15, 2013, at 5:59 PM, Kent Osterberg <[email protected]> wrote: > Jesse, > > Running PVWatts for various tilt angles with an azimuth angle of 135° (or > 225°) for locations in Minneapolis, shows that the optimum tilt angle for > annual energy production is about 35°, that's almost the same as the optimum > tilt with an azimuth of 180°. To maximize December energy production with the > 135° azimuth, the optimum tilt angle is about 60° and that gives 12% more > energy in December than the 35° tilt would (without considering how much > better the steep tilt does at shedding snow). The SE roof with the steeper > pitch is certainly the better choice. > > Kent Osterberg > Blue Mountain Solar, Inc. > www.bluemountainsolar.com > On 5/14/2013 8:23 PM, Jesse Dahl wrote: >> Allan, >> >> That is pretty much my thinking. They have 0 interest in stepping foot roof >> and the SE give more tilt and easy ground access to clear the array during >> winter. >> >> I appreciate the advice. >> >> >> Jesse >> >> Sent from my iPhone >> >> On May 14, 2013, at 10:15 PM, Allan Sindelar <[email protected]> >> wrote: >> >>> Jesse, >>> Based only on the info you provided, I'd recommend the SE face. A low slope >>> is best for maximizing annual gain, which is what a conventional grid-tie >>> customer would want. But you are in essence giving them a system that will >>> function as GT now, but as an off grid system if the grid goes down. Under >>> that scenario, I would sacrifice annual spin-the-meter-backward production >>> in favor of maximizing winter output, when days are shortest and loads are >>> greatest. A steeper array pitch will maximize available charge during >>> winter, while the shallow pitch will be great in summer but close to >>> nothing in winter. Given their stated objective, explain the tradeoff as >>> offering the best preparation for lack of grid. >>> >>> I'd advise otherwise if they clearly want to seasonally adjust their array >>> if there is an outage, and you install adjustable-tilt racks, and the >>> owners are afraid of neither ladders, heights, or snow. >>> >>> We just completed a 4 kW GTBB system for a customer with similar >>> objectives. We used 16 240W modules on two 8-module pole-top racks, with >>> the instruction to leave the tilt angle shallow as long as the utility is >>> present, but tilt to 45-55 degrees in winter during an extended outage. >>> (And a pair of Classic 200s to handle the 4-module series strings.) >>> Allan >>> >>> Allan Sindelar >>> [email protected] >>> NABCEP Certified Photovoltaic Installer >>> NABCEP Certified Technical Sales Professional >>> New Mexico EE98J Journeyman Electrician >>> Founder and Chief Technology Officer >>> Positive Energy, Inc. >>> 3209 Richards Lane (note new address) >>> Santa Fe, New Mexico 87507 >>> 505 424-1112 >>> www.positiveenergysolar.com >>> >>> >>> >>> On 5/14/2013 4:34 PM, Jesse Dahl 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: [email protected] >>>> >>>> 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: [email protected] >>> >>> 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: [email protected] >> >> 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: [email protected] > > 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 >
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