Re: [RE-wrenches] Using the North Facing Roof
I want to give back to this forum that has been so valuable to me, so here it is... a tool for you to quickly compile data for multiple compass orientations for a given pitch... http://floridasolardesigngroup.com/pva/do-pvwatts-wrenches.php This PVWATTS derived tool will give you 36 data points for solar energy production with every azimuth from 0º to 350º at 10º increments for a given location and pitch. You can enter your desired system size to model its output and include your desired PVWATTS derate (system loss) factor. It will download a .CSV file each time you run the tool. You can run it for a variety of tilt angles based on your needs to compile data for your own study. There are limits on use, but if everyone does not run out and use it at the same time it should be fine. Once you get your data into a spreadsheet you can easily slice and dice it any way you want and make some great visualizations. [image: Inline image 1] Enjoy! Jason Szumlanski On Tue, Jul 28, 2015 at 7:01 PM, Allan Sindelar al...@sindelarsolar.com wrote: I am paying close attention to this thread, but for different reasons. I have designed and will install next month an off grid system for a high-elevation research hut. At 14,242' I believe this will be the highest elevation off grid system in the continental US (Alaska too?), at the Summit Hut atop White Mountain, east of the Sierra crest in eastern California (wmrc.edu/facilities/bar/summit.html). For me it's sort of a post-retirement summer working adventure. A nearly identical system will serve an older observatory at 12,700' in the same area. The Summit Hut will get a roof array where winds of 190 mph have been measured, I'm told. The roof has about a 5º north-facing tilt. I'm old-school too, thinking in terms of a 25º tilt to south. But other than powering an internet repeater all year, the system is only used during the summer months, mid-June to mid-October, when the snow has melted and it's accessible by a long jeep trail. So in that respect it's similar to a flat- or north-facing array in a grid-tied system, where only summer gain matters much and a southern tilt matters less that I want to believe. Jason's chart is pretty useful here, suggesting that I should pay more attention to handling wind loads with a low angle than maximizing summer gain. Allan *Allan Sindelar* al...@sindelarsolar.comal...@sindelarsolar.com NABCEP Certified PV Installation Professional NABCEP Certified Technical Sales Professional New Mexico EE98J Journeyman Electrician Founder (Retired), Positive Energy, Inc. *505 780-2738 505%20780-2738 cell* On 7/28/2015 11:15 AM, billbroo...@sbcglobal.net wrote: Larry and Peter, You are too old-school to think outside the box. It’s not about direct sunlight—it’s all about kWh/m^2/day and those numbers don’t lie. Your analysis is not correct and this is why simple analyses will always give you a wrong answer. North-facing arrays have been financially attractive for years, but many have not done it due to taboos or bad analysis. Reverse-tilt arrays often look horrible and should be avoided particularly on the street-side of a house. Also, the structural impacts of tilted arrays on residential rooftops are not well-understood so wind-loading calculations are complex at best. We have been using east and west facing roofs for your years so what’s the big deal about north? I put together the one of the first tables of orientation version performance way back in 2001 for the California Energy Commission to combat the misconceptions that PV arrays had to be mounted at 45-degrees facing South (the prevailing misconception at the time). I didn’t print the North facing numbers because the concept would have blown people’s minds at the time—they weren’t ready for the truth. 30-degrees facing south is optimal in most latitudes from 20-degrees to 50-degrees. (perfect in most locations) 4:12 pitch (18-degrees) facing south is 97% of perfect. 4:12 pitch east or west is 88% of perfect. Flat is 89% of perfect. 4:12 pitch facing north is 75% of perfect. The truth shall set you FREE. Bill. *From:* RE-wrenches [mailto:re-wrenches-boun...@lists.re-wrenches.org re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of *Starlight Solar Power Systems *Sent:* Tuesday, July 28, 2015 9:41 AM *To:* RE-wrenches re-wrenches@lists.re-wrenches.org re-wrenches@lists.re-wrenches.org *Subject:* Re: [RE-wrenches] Using the North Facing Roof In Yuma, AZ, north facing modules will have direct sunlight for small part of the year. In the picture, look at the yellow area above the East-West line. Thats direct sunlight from the north. The green top line in the picture shows summer solstice showing sunlight from sunrise to about 0930 and from 1530 to sunset. The energy harvested during those hours will be tiny compared to the peak sun hours on the south side. The angle of incidence
[RE-wrenches] Solectria PVI Series inverter problems
Friends: We have just begun using the Solectria PVI series inverter. I fear these inverters may fall off the wall. There is no positive way of attaching the inverter to the bracket, it just rests on there by the grace of gravity. The bracket is very narrow, about 4 inches wide, and the height of the inverter presents a lot of leverage on this small bracket. The electronics sections is seperateable from the connection box, but the connection box will then be left floating in the air, suspended only by the conduits. Point 2: The manual indicates the inverter needs to be mounted on non-flammable surfaces. This makes me wonder how hot the inverter gets? This limits mounting options: you can't mount them on wood siding and you can't use plywood to span studs. Point 3: There are also some problems with the manual. I have detailed all of these problems in a web page called, What's wrong with the Solectria PVI Series? The link is: http://www.millersolar.com/MillerSolar/case_studies/Solectria/Solectria.html I contacted Solectria about these problems and all I get are promises. I am curious: Does anyone else feel that this mounting system is inadequate? Unfortunately, we started using these just after we attended a seminar presented by Solectria. I was not able to ask them in person why the PVI series inverter has such an inadequate mounting system. If anyone else has complaints about the Solectria, I'd like to hear them. I am real close to banning them from our inventory until these problems are resolved. If there are other problems I have not encountered, I want to factor that in to my decisions. Thanks in advance, William PS: Point 4: Just to get all of my complaints in one place, tech support is pretty marginal with Solectria. A few weeks ago I called and the tech support person did not have access to any of the manuals! I have called them for 4 weeks now and have not received one call back. I called again just now and waited on hold for several minutes, only to be presented with a recording to leave a message. This is pretty bad in itself, but then the mail box was full and would not accept my message!? This is not the indication of a well-founded company. William Gradient Cap_mini Lic 773985 millersolar.com http://www.millersolar.com/ 805-438-5600 ___ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html List rules etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org
Re: [RE-wrenches] Solectria PVI Series inverter problems
I haven't used the PVI so I can't comment on the mounting issue but my past experience with Solectria and tech support was similar to yours. Jesse Sent from my iPhone On Jul 29, 2015, at 6:19 PM, William Miller william.mil...@millersolar.com wrote: Friends: We have just begun using the Solectria PVI series inverter. I fear these inverters may fall off the wall. There is no positive way of attaching the inverter to the bracket, it just rests on there by the grace of gravity. The bracket is very narrow, about 4 inches wide, and the height of the inverter presents a lot of leverage on this small bracket. The electronics sections is seperateable from the connection box, but the connection box will then be left floating in the air, suspended only by the conduits. Point 2: The manual indicates the inverter needs to be mounted on “non-flammable” surfaces. This makes me wonder how hot the inverter gets? This limits mounting options: you can’t mount them on wood siding and you can’t use plywood to span studs. Point 3: There are also some problems with the manual. I have detailed all of these problems in a web page called, “What’s wrong with the Solectria PVI Series?” The link is: http://www.millersolar.com/MillerSolar/case_studies/Solectria/Solectria.html I contacted Solectria about these problems and all I get are promises. I am curious: Does anyone else feel that this mounting system is inadequate? Unfortunately, we started using these just after we attended a seminar presented by Solectria. I was not able to ask them in person why the PVI series inverter has such an inadequate mounting system. If anyone else has complaints about the Solectria, I’d like to hear them. I am real close to banning them from our inventory until these problems are resolved. If there are other problems I have not encountered, I want to factor that in to my decisions. Thanks in advance, William PS: Point 4: Just to get all of my complaints in one place, tech support is pretty marginal with Solectria. A few weeks ago I called and the tech support person did not have access to any of the manuals! I have called them for 4 weeks now and have not received one call back. I called again just now and waited on hold for several minutes, only to be presented with a recording to leave a message. This is pretty bad in itself, but then the mail box was full and would not accept my message!? This is not the indication of a well-founded company. William image002.jpg Lic 773985 millersolar.com 805-438-5600 ___ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html List rules etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org ___ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html List rules etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org
[RE-wrenches] Magnum buzz box
I installed a Magnum 4448 PAE today, and it makes an unacceptable amount of noise. The backplate is mounted with Tapcons to a concrete block wall. Does anyone have any tips for quieting this thing down? Would a rubber membrane, mounted behind the backplate help. Other Magnum inverters I've installed are a bit noisy, but this one is over the top. Thanks, Drake ___ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html List rules etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org
