Wednesday, February 10, 2010

Quick thoughts on Solyndra solar tubes in Ontario

(disclaimer: I have not studied this extensively, so the following is not authoritative)

The Solyndra solar tubes are mounted over a roof covered in a white plastic. Their added efficiency claims are due to light reflected off the roof and captured by the back side of these tubes. Because the tubes are round as the sun changes position during the day and through the year they plausibly can capture a bit more of the sun than a flat panel. My concern with this technology for Ontario is that the design is to have the tubes mounted at 1' which means that for a few months of the year they are likely to be covered by snow, or the angle of reflection off the snow below the tubes is less optimal. That may erase the gains that this system would have in other times of the year. This system requires that the roof needs to be flat, with little slope and needs the white plastic coating on it. So this is suited for commercial flat roofs that are new, or that require a "new roof" (typically every 20 years).

Another issue with these tubes is that they use "CIGS" which is considered the most environmentally detrimental of solar technologies (cadmium in particular). Supposedly this material is recyclable, but that may not be cheap or easy to do. I suspect that it is easier to recover these materials from these glass tubes than on laminated surfaces?

In terms of financial position, Solyndra is gearing up to IPO but they may have a tough time if silicon prices do not increase, or they cannot drive prices down comparatively. They and other thin-film technologies looked much better leading up to 2009 when technologies comparatively cheaper to silicon based solar and hence why Gunter Report predicts that Solyndra will flop this year. Strangely many in the solar industry are quite conservative about new technologies (I say strange as solar is all relatively new and one would expect that the field attracts more risk takers), so refutation and pessimism about new ideas always abound. I think that perhaps Solyndra is an interesting niche technology, but that it is better suited for lower latitudes and places without snow. I welcome input if you have any.


  1. it works the opposite. Evacuated tubes such as solhydra allow the snow to wall between and so not build up.

    I know because i have 300 of them in sweden

  2. Solyndra tubes can be installed at 500mm from the roof surface. White roofs are more common these years, mainly to reduce the heat island effect over cities. Snow will reflect sun's rays as good as a white membrane, albedos are similar. BTW, singleply white membranes roofs will last up to 40 years in PVC or PIB, reference: British Bord of Agrément 08/4531, 02/4922... so it seems better than flat panels even on the long run (more than 20 yeas). See also a new book entitled Sustainable Green Roofs published in French: Toits verts et durables, ISBN 9782981232304.

  3. Too bad, Solyndra is closed in the States since a few weeks.
    THe idea was bright, very bright, but the low cost of flat photovoltaic panels filled the cylinder's one.
    Cost of electricite was around 2,40$ per watt with Solyndra compare to a cost somewhat as alow as 1,20$ per watt, so about half the price. Go figure, even on a low E roofing membrane?

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