I have yet to see a flat plate collector outperform an EV tube setup. With EV tubes the angle of incidence is almost always at 90 degrees throughout the course of the day and the sun's arc. Except for very early in the morning and very late in the afternoon, you always have the most/maximum solar absorption - 90 degrees from the face of the collector. Does anyone have a different experience?
Roger Dixon Certified Wind Site Assessor Distributor & Installer of Solar & Wind Energy Systems Skylands Renewable Energy, LLC 908.337.2057 cell 908.730.6474 fax roger.di...@skylandsre.com www.skylandsre.com Note: The information contained in this communication is confidential, may be attorney-client privileged, may constitute inside information, and is intended only for the use of the addressee(s). It is the property of the sender of this e-mail. If you receive this e-mail in error, do not review, disseminate, or copy it. Unauthorized use, disclosure, or copying of this communication or any part thereof is strictly prohibited and may be unlawful. If you have received this communication in error, please notify the sender immediately by return e-mail and destroy this communication and all copies thereof, including all attachments. -----Original Message----- From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Kelly Keilwitz, Whidbey Sun & Wind Sent: Monday, July 20, 2009 3:12 AM To: RE Wrenches listserve Subject: Re: [RE-wrenches] Tube solar collectors All, Apricus ET's have a cylindrical absorber surface, which are significantly better at capturing low angle of incidence energy. I have both a Thermomax (with flat collector plate internal to the tube) and Apricus collector in parallel on my own home and see significantly better temperatures early and late in the day on the Apricus collector. IMO, ET's have a distinct advantage in our cool, windy, and low-snow environment (northern Puget Sound). Kelly Keilwitz, P.E. Whidbey Sun & Wind, LLC Renewable Energy Systems NABCEP Certified PV Installer 987 Wanamaker Rd, Coupeville, WA 98239 PH & FAX 360-678-7131 sunw...@whidbeysunwind.com On 7/19/09 7:29 PM, "Darryl Thayer" <daryl_so...@yahoo.com> wrote: > > HI Joel > I have done ev tube and flat plat, I am amazed that the flat plate is almost > as good to better than the ev tube. > > As to PV it is true that the output goes as the angle, (cosine function) but > if you have a wavey surface it is very slightly better than a flat surface. > the cosine effect is there for the entire array, and the modern modules with > antireflective coating compensate for much of the reflected energy. So I > doubt that the tubes are any better. > Daryl > > --- On Sun, 7/19/09, Michael Welch <michael.we...@re-wrenches.org> wrote: > >> From: Michael Welch <michael.we...@re-wrenches.org> >> Subject: Re: [RE-wrenches] Tube solar collectors >> To: "RE-wrenches" <re-wrenches@lists.re-wrenches.org> >> Date: Sunday, July 19, 2009, 12:27 PM >> Hi Joel. No experience here, but I >> did talk to one of their installers (I think it was Carlisle >> Energy Services) at Intersol last week, displaying one of >> the modules with its mounting system. Some additional info >> to consider: >> >> E-T thermal collectors do have a "flat plate" in each tube, >> so angle of incidence is still critical. >> >> Solyndra's have wrap-around PV materials inside their >> tubes, so E-W angle of incidence stays the same throughout >> the day. >> >> They recommend reflective (like white) roof coating which >> picks up more bounced sunlight from the bottom side. >> >> But it seems to me the main advantage is that they do not >> require roof penetrations or even ballast, making them a >> potentially quicker and cheaper install. The claim is that >> wind underneath will not lift them, and if wind load >> requirements are higher than normal (not sure where they >> draw the lines), merely putting skirting around the outside >> edge of the array keeps the wind out from underneath the >> modules. >> >> All that said, I also look forward to hearing about field >> experience and performance. >> >> Joel Davidson wrote at 07:15 PM 7/18/2009: >> >>> Wrenches, >>> >>> Solyndra claims that their tube collectors "perform >> optimally when mounted horizontally and packed closely >> together, thereby covering significantly more of the >> available roof area and producing more electricity per >> rooftop on an annual basis than a conventional panel >> installation." See http://www.solyndra.com/Products/Greater-Rooftop-Coverage >>> >>> It is my understanding that a solar thermal or PV tube >> or flat plate collector's performance is based on the angle >> of incidence and that curved collector performance decreases >> as the angle of incidence moves away from perpendicular. >>> >>> Does anyone have any field experience with solar >> thermal evacuated tube collectors or Solyndra PV to show >> that tubes perform better than flat plate collectors? >>> >>> Joel Davidson _______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options & 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 Options & 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
