Interesting video! I can understand there will be sites and use cases where vertically mounted bifacial modules are a good solution. I just can't let it slide without saying that every single module install manual I have seen over the past 20 years says: "*do not focus or magnify sunlight with mirrors"* since the current-carrying materials are not rated for the higher current that comes with concentrated irradiance.
While he was using mylar, real mirrors can cause fires and personally I would not encourage amateurs to test this out! Just one example, my parents had a fire start in their bathroom from a mirror reflecting sunlight onto a towel. Of course modules can be designed for higher irradiance, but I would bet the cost of larger wires + reflecting materials + cleaning the mirrors tips the scales to prohibitively expensive. Grateful as always for the interesting conversations on the wrenches list! [image: Screenshot 2024-12-08 at 9.11.57 AM.png] Rebekah Hren Licensed Electrical Contractor NABCEP Certified Solar PV Installation Professional™ 091209-85 Tel: 336.266.8800 On Sun, Dec 8, 2024 at 8:03 AM Garrison via RE-wrenches < re-wrenches@lists.re-wrenches.org> wrote: > > Hi Howie, > > I have found one scenario where heat tape can help with snow on solar. > > As we know, solar panels warm up in the sun and melt snow even when > ambient temperatures are below freezing. The water from this melting snow > drips off the array and slush/snow can slide off the panels. > > On a cold day, in a well insulated home, or a home with large overhangs, > the water dripping off the array will freeze when it hits the roof below > the panels. This can create an ice dam that can be an issue for the roof if > not properly installed, and also create a barrier to snow shedding from the > array. If conditions are right this dam can get quite large and prevent > panels from working for a long time in the winter. I have also seen ice > dams cause damage to roofs and gutter systems and creep under the lowest > row of flat flashings (not micro flashings, yet at least) causing moisture > issues. > > The is not an issue on all roofs, but can be on many flush mount arrays, > on a medium sloped roof (maybe 25-35 degrees), that end maybe 2’ or so from > the gutter. Well insulated homes, and/or homes with large overhangs are > especially good candidates for this type of ice build up. > > In these scenarios a gutter ice melt system that extends up the roof 18” > or so can help eliminate this refreeze issue. > > I don’t think the cost of the ice melt system installation or operation > would be offset by the extra energy you would get from the array, but it > would help prevent ice dams which adds additional value. > > Personally I would never try to mount any type of ice melt directly to > panels. I could see it possibly causing damage to the panels and could also > exacerbate this melting/refreeze/ice dam issue if you melt snow when > ambient/roof surface temps are below freezing. > > Ps. Very interesting vertical east/west video Dave! As we lose net > metering here in Illinois people on time of use with east-west arrays will > retain the most benefit from their grid tied systems. I hadn’t considered > the extreme of vertical bifacial easy-west, but it is very interesting to > see some data. > > Best, > Garrison > > Garrison Riegel > Celestar Solar > (c) 773-515-5168 > (e) garri...@celestarsolar.com > > > On Dec 8, 2024, at 8:05 AM, david quattro via RE-wrenches < > re-wrenches@lists.re-wrenches.org> wrote: > > > Here is a very interesting video about vertically mounted bifacial modules > - performing surprisingly well. > https://www.youtube.com/watch?v=xD1MT-ek05w > > > > > > On Sat, Dec 7, 2024 at 4:36 PM John Blittersdorf via RE-wrenches < > re-wrenches@lists.re-wrenches.org> wrote: > >> I'm starting to think that Vertical panels are the only sure fire way to >> keep them clear. I did a small cabin years ago with 2 panels on the south >> wall of the cabin. All they wanted is a few lights and cell phone charging >> and rarely used in the winter. It worked great. Their Trace 1200 watt >> inverter was turned off when they were not there and the C40 kept the >> batteries charged over the winter without any problems. Now I am >> stressing over an unreachable camp on an island (you may know this one >> Kirk) where I updated a 12V system with outback inverter and about 1kw of >> solar which had been shut down in the winter months. I replaced the >> inverter with >> a VFX3648, added an FM100, Installed 5 kw of PV on a ground mount at 45 >> degrees (mistake- should have done 60 degrees or more with more space at >> the bottom but assumed not much snow there, all to run a Starlink and >> Optics monitoring and lots of cameras. 60 days into this saga today at 4 >> pm, the signal was lost. Is it snow or ice on the panels, or just lack of >> enough sun (which has been minimal) which caused low battery cutoff. >> Batteries are new AGMs and I set cutoff at 45.2. I didn't want to run them >> too low. If I had some of the panels vertical and 4' above the ground, I >> could probably be assured that snow would not stay on long. Our problem >> here in Vermont is that when the clear >> weather arrives, it usually comes with frigid cold and ground and pole >> mounts are kept frozen by the ambient temperature until the sun can warm >> them up but that doesn't happen with 6" on snow on the face. Only above >> freezing >> temperatures or still air with intense sun will clear them. I'm working >> on a ground mount now that was started by a previous owner of a property >> where the base for the ground mount array is a post and beam substructure 4 >> to 8 feet above the ground. I'm thinking about putting 4 panels vertical >> and 4 at 45 degree angle on the north edge of the structure and 8 panels at >> a summer angle on the South edge with adequate space for snow shedding. . >> We have a temporary array at Approx 35 degree angle that has somewhat shed >> the snow but with no space for snow buildup, the shedding stops. >> >> I am planning to build a fence around my garden this summer with PV >> mounted vertically with the stacks of 110 watt modules I have accumulated >> from repowering pole mounts. South and North side of garden facing south >> and the east and west sides facing east and west. Any thoughts on this >> crazy idea? >> >> John Blittersdorf >> Off Grid Vermont >> >> >> >> On Fri, Dec 6, 2024 at 1:51 PM Dana Orzel via RE-wrenches < >> re-wrenches@lists.re-wrenches.org> wrote: >> >>> Having installed at up to 13,200’ elevation (60° rack mount) and in snow >>> country for most of most of 37 years and dealing with installations by >>> others that almost or completely come off the roof here is my 0.02: >>> >>> >>> >>> Low angle roofs less than 35deg seem to take on most of the damage >>> incidents. Avalanches are most prevalent at 32-35+deg. Avys tend not to >>> slide at less than 32 deg. >>> >>> Is the lower edge of the array shaded or partial shade on part of the >>> array with the low angle winter sun? This allows for ice up on the bottom >>> edge or on a section of the array. >>> >>> Is there a drop zone for the snow? I use 5’ min below the leading edge >>> for a mountain install I would increase this to higher. >>> >>> I know this sounds obvious - Is there a snow fence or obstruction (door >>> shed roof) below the array? >>> >>> >>> >>> I now install esp. on lower angle roofs a mid-third rail & use 50% more >>> contact to the roof points (cheap array life insurance). >>> >>> If using a micro inverter or optimizer – attach this to the panel so it >>> flexes with the panel if necessary not the rail mount system. Watch out for >>> bolts that stick up close to the back sheet. >>> >>> >>> >>> Happy Hollar Daze all! >>> >>> _________________________________________________________ >>> >>> Dana Orzel GREAT SOLAR WORKS! >>> >>> C – 208.721.7003 E – d...@solarwork.com >>> >>> W - www. greatsolarworks.com www.solarwork.com >>> >>> *“Responsible Technologies for Responsible People since 1988!”* >>> >>> >>> _______________________________________________ >>> List sponsored by Redwood Alliance >>> >>> Pay optional member dues here: http://re-wrenches.org >>> >>> 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 >>> >>> There are two list archives for searching. When one doesn't work, try >>> the other: >>> https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/ >>> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >>> >>> List rules & etiquette: >>> http://www.re-wrenches.org/etiquette.htm >>> >>> Check out or update participant bios: >>> http://www.members.re-wrenches.org >>> >>> _______________________________________________ >> List sponsored by Redwood Alliance >> >> Pay optional member dues here: http://re-wrenches.org >> >> 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 >> >> There are two list archives for searching. When one doesn't work, try the >> other: >> https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/ >> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >> >> List rules & etiquette: >> http://www.re-wrenches.org/etiquette.htm >> >> Check out or update participant bios: >> http://www.members.re-wrenches.org >> >> _______________________________________________ > List sponsored by Redwood Alliance > > Pay optional member dues here: http://re-wrenches.org > > 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 > > There are two list archives for searching. When one doesn't work, try the > other: > https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/ > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > http://www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > http://www.members.re-wrenches.org > > _______________________________________________ > List sponsored by Redwood Alliance > > Pay optional member dues here: http://re-wrenches.org > > 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 > > There are two list archives for searching. When one doesn't work, try the > other: > https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/ > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > http://www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > http://www.members.re-wrenches.org > >
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