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MIT Solar Towers Beat Solar Panels By Up To 20x

Posted by timothy on from the if-they-had-pants-they'd-have-been-beaten-off dept.

An anonymous reader writes "A team of MIT researchers has come up with a very different approach to solar collectors: building cubes and towers that extend solar cells upward in three-dimensional configurations. The results from the structures they've tested show power output ranging from double to more than 20 times that of fixed flat panels with the same base area (abstract, full pre-print). The biggest boosts in power were seen in the situations where improvements are most needed: in locations far from the equator, in winter months and on cloudier days."

19 of 159 comments (clear)

  1. Picture... by Anonymous Coward · · Score: 5, Informative

    Picture available here. It's a solar pancake!

    1. Re:Picture... by Firethorn · · Score: 3, Informative

      That's an interesting article, but I found the link about using an ion cannon to make cells 1/10th as thick at 1/2 the cost of cheap chinese cells to be potentially more revolutionary.

      At this point we're not especially limited on space for solar installs. Our problem is that our collection systems aren't cheap enough.

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    2. Re:Picture... by uigrad_2000 · · Score: 4, Informative

      The Ion cannon article was featured on Slashdot two weeks ago.

      I think a better way to state it, would be to say that efficiency per square foot of ground used is not important, unless the cost of the cells come down.

      Now that there is word of a new manufacturing process to reduce cost, two weeks later, we find an article about how to arrange low-cost cells.

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    3. Re:Picture... by pla · · Score: 3, Informative

      At this point we're not especially limited on space for solar installs. Our problem is that our collection systems aren't cheap enough.

      This. These 3d shapes give a better yield for a given footprint, but actually cost more.

      Hey, If you can make individual flat panels cheaply enough, I'll pave half an acre with them for all I care about the "footprint". That said, I really don't understand why no major company has come up with mass produced smaller panels in a roofing-shingle form factor, but, entirely different topic.

      Now, the part of this that does appeal to me involves the improved yield at high latitudes - But does that mean improved only against the footprint, or against the surface area? If the former, hey, cool, I live just far enough North that solar won't realistically pay back the investment given the present dominant efficiencies and prices; If the latter, then to repeat myself, just make 'em cheaper, I'll provide the space.

    4. Re:Picture... by fast+turtle · · Score: 4, Informative

      Did you RTFA? I happened to do so having caught it a couple of days ago. The interesting element to this design is the early/late (dawn/dusk) power generation as the current method doesn't get enough solar incidence to generate anything until 3 hours after sunrise/3 hours before sunset. That's 6 hours of production that's being missed, which is why this design reaches 15-20x the generated power of conventional flat panels.

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    5. Re:Picture... by icebike · · Score: 3, Informative

      Yeah, I read dud RTFA. It said:

      While the cost of a given amount of energy generated by such 3-D modules exceeds that of ordinary flat panels, the expense is partially balanced by a much higher energy output for a given footprint, as well as much more uniform power output over the course of a day, over the seasons of the year, and in the face of blockage from clouds or shadows.

      This suggests to me that there is no ROI on this method, or at least none that could not be more cheaply matched by simply tilting existing solar arrays.

      I don't discount the possibility that we are seeing another poorly written TFA, and that there is an eventual ROI. But the implication is that the generation of power early and power late in the day may never actually pay for the structures and maintenance needed to collect it, leaving you with zero net gain over a tilted array in northern latitudes.

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  2. Prior art... by msauve · · Score: 3, Interesting

    So, MIT has basically recreated what a 7th grader has previously done.

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    1. Re:Prior art... by msauve · · Score: 3, Interesting

      So, the middle schooler had an idea, built it, then collected data. MIT modeled theirs first to predict behavior before building it. Meh. "Systematic and predictive analysis," that's just obfuscatory-speak.

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    2. Re:Prior art... by DerekLyons · · Score: 3, Insightful

      Well, no. The 7th grader built a single physical model and made rough measurements of it's performance at a single location across a limited span of time. The MIT team built a computer model that can analyze any given configuration and simulate it's output across a wide variety of locations and wide span of time - including variations in seasonal weather patterns.

      I'm not saying that what the 7th grader did wasn't cool - but he's built a pinebox derby car, while MIT has built a fully solar powered 55mph family sedan. Apples-to-oranges doesn't even *begin* to describe the differences, not only of degree but of kind, between the projects.

    3. Re:Prior art... by mutube · · Score: 3, Informative

      According to this Wired article the 7th graders work has been 'debunked' (or rather disproven) due to not actually testing power output but rather the 'open voltage on the circuit'. Unfortunately both the links in the Wired article point to Google webcache results that have expired so it's not possible to verify.

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    4. Re:Prior art... by Endo13 · · Score: 3, Informative

      Apologies. Reread the GP post and realized the above links don't really deal with what he was getting at.

      Here's one that's a bit more helpful, but still doesn't have all the details. It appears all the sites and cached pages are gone.
      http://www.treehugger.com/clean-technology/blog-debunks-13-year-olds-solar-power-breakthrough.html

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  3. paper link by Trepidity · · Score: 4, Informative

    As seems depressingly common in science journalism, they vaguely mentioned the existence of a paper, but don't actually give the title or (dare we hope) a hyperlink to the paper. At least they did mention the name of the journal it was published in.

    In any case, the paper is "Solar energy generation in three dimensions." If you're at a university with a subscription the official version (not open-access) is here. There is also an open-access preprint version at the arXiv.

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  4. But much harder to set up by Hentes · · Score: 5, Interesting

    Most people use solar panels because they can be comfortably put on rooftops. If someone has enough room for these 3D structures they could just install a Sun tracking system that's even more efficient.

    1. Re:But much harder to set up by DerekLyons · · Score: 3, Insightful

      If someone has enough room for these 3D structures they could just install a Sun tracking system that's even more efficient.

      Under conditions where you can see the sun - that's true. But the point of TFA is that these 3D structures are more efficient *in situations where sun trackers aren't more efficient*.

      Conditions exactly like those currently outside my window - where the sky is nearly uniformly bright but you cannot see the sun at all due to the clouds. Conditions that are fairly common here in the Pacific Northwest.

  5. misleading by demonbug · · Score: 5, Insightful

    20x output (compared to a flat panel with the same footprint).

    Not really news. This is like excitedly proclaiming that a 20 story building has nearly 20 times the floorspace of a single story building with the same footprint. Uh, no shit? (Or that a 20 story building receives more insolation than a 1-story building; hmm, you think maybe it has a lot more surface area?) I also like that they hand-wave away the fact that it costs significantly more per unit output by saying that cells are getting cheaper. Great.

    Not that there aren't uses - it absolutely makes sense to go this route where you have limited footprint space - but it just doesn't seem at all revolutionary. I guess if you tack the letters M-I-T onto a press release it instantly becomes newsworthy.

  6. Re:Costs more by chudnall · · Score: 3, Informative

    The time is ripe for such an innovation, Grossman adds, because solar cells have become less expensive than accompanying support structures, wiring and installation. As the cost of the cells themselves continues to decline more quickly than these other costs, they say, the advantages of 3-D systems will grow accordingly.

    “Even 10 years ago, this idea wouldn’t have been economically justified because the modules cost so much,” Grossman says. But now, he adds, “the cost for silicon cells is a fraction of the total cost, a trend that will continue downward in the near future.” Currently, up to 65 percent of the cost of photovoltaic (PV) energy is associated with installation, permission for use of land and other components besides the cells themselves.

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  7. Re:Duh by ILongForDarkness · · Score: 5, Interesting

    I agree about shadow effects. More comes into play though since more angles will be approximately normal to the panels more angles of light will still be in an effective region of the panel for collecting. In winter in the non-tropical regions the sun's maximum height can be pretty low in the sky giving you a very oblique angle to fixed panels against a roof (assuming a shallow slope on the roof). Making these suckers stick up means that the crossection exposed to the sun is larger even if the sun is lower in the sky.

    That said two problems I see:

    1) Roof top intallation will be weight. I have panels on my roof and they are about 100lb per sq yard. Stack twenty together and you'd be looking at 2000lb per sq yard. Not a good thing for the roof.

    2) Ground based panels: you can put the panels on stands that can be adjusted, heck they can be motorized so they can track the sun through the day AND through the seasons. So why exactly would you by ~20X more panels (at about 200 a pop) when a $50 motor per panel (guessing), or an adjustable stand that someone goes out and tilts every month or so can have the same affect?

  8. Who killed the effecient solar array? by TraumaFox · · Score: 3, Insightful

    Quick, someone alert all of the major energy companies so they can buy up the patents and sit on them for eternity!

  9. Re:Duh by 93+Escort+Wagon · · Score: 3, Funny

    That is not correct. Re-read the article.

    "Re-" read?

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