Announcement

Collapse
No announcement yet.

Tuned radiative cooling for PV solar panels?!

Collapse
This topic is closed.
X
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • #16
    Originally posted by DanKegel View Post
    Quite. The only remaining somewhat mysterious bits are

    - is the reference to the "cold of space" a canard? Presumably it's good to emit in the atmosphere's "transparant region", 8 - 13 μm, as there's little ambient irradiation at that wavelength, so being an efficient absorber there doesn't heat up the cell as it would at other wavelengths? If so, why do they talk about using layers that emit at >= 4 um?

    .
    It is true that open space is a black body radiator whose radiation temperature when not looking at a star or gas cloud is very low (essentially the background radiation from the big bang.)
    So anything that makes it through the atmosphere will not come back again. And the incoming radiation will be of low intensity AND a low radiation temperature profile.
    SunnyBoy 3000 US, 18 BP Solar 175B panels.

    Comment


    • #17
      Originally posted by DanKegel View Post
      Yup. Hopefully those pyramids are easy to fabricate with standard photolithography, and make sense as part of a solar panel.

      If not, there are probably a couple dozen other little tweaks being worked on at any one time, and one or so of them might make it out of the lab and into production in any given year, bumping up efficiency by a tiny percentage. (e.g. the smaller and more numerous busbars coming into use lately).
      I agree that more busbars will help harvest more electrons but at some point too many or too thick will reduce the amount of pv cell area that receives the sunlight to generate those electrons.

      My research was trying to reduce the sheet resistivity of the cell that would allow the electrons to move quicker across the surface to the busbars. Unfortunately there was a break point there as well since even at the lowest resistance there just wasn't enough electrons being generated to be harvested. So the trend went away from the CdS thin film technology to other solid state materials.

      Comment


      • #18
        Sounds like the technique's being tested as an addon to HVAC systems rather than solar systems now.
        Still not commercialized, still speculative, still far from market.

        nature.com/articles/nenergy2017143

        technologyreview.com/s/608840/a-material-that-throws-heat-into-space-could-soon-reinvent-air-conditioning

        To those who jump on reports like this and criticize them for being pie in the sky: bite a rock It's still interesting.

        Comment


        • #19
          Originally posted by DanKegel View Post
          Sounds like the technique's being tested as an addon to HVAC systems rather than solar systems now.
          Still not commercialized, still speculative, still far from market.

          nature.com/articles/nenergy2017143

          technologyreview.com/s/608840/a-material-that-throws-heat-into-space-could-soon-reinvent-air-conditioning

          To those who jump on reports like this and criticize them for being pie in the sky: bite a rock It's still interesting.
          Dan: It's interesting in the same way most of the rest of your stuff is interesting - it's junk science, and more - it's old news. Very old. Try a history forum if you're looking for attention.

          For starters, the idea has been around as long as the science of radiative heat transfer has been studied. The ideas are well developed. Only the blather changes. The tech. for the mfg. aspects for radiative cooling applications needs work, and until radiative cooling can be made as cost effective as available methods, it'll be a sliver market.

          This is the type of subject folks looking to fill columns of print in greenwashing and junk science media use to sell their rags and ideas to rubes who then repeat them as new and undiscovered miracles and thus, as perhaps for this application, create more opportunities for conmen to metaphorically sell tin foil hat radiative coolers to fools and separate them from their assets. And that's what your behavior is doing.

          I wrote a couple of papers as an undergrad that dealt with what are called selective surfaces. There are many ways to accomplish the goal of selectively changing the radiative properties of a surface as f(wavelength) for the purpose of either enhancing or decreasing radiation heat transfer. In practice, at least for the last 50 years or so, decreasing radiative heat transfer properties of objects by using what are called selective surfaces has become commercialized and practical, if not completely cost effective. Surface treatments and materials for radiative cooling are less well developed and have a way to go before commercially viable and competitive with currently available methods. That makes them the darling of hucksters.

          I did not pursue the information you post. But, that you dredge up what's probably more of the usual junk science you spew around here and then add it to a 2 year old post that referenced more pie-in-the -sky crap is no more than another example of your greenwashing behavior that I believe is rude, self serving and hurtful, particularly to the uninformed who don't know any better. It's also a disservice to those who what R.E. to succeed. Your actions spread false hope and misinformation both directly and by innuendo.

          As for biting a rock: Bite me Dan. Your spreading half truths and junk science. It's only interesting in the same way science fiction is interesting. I'm calling B.S. on it (again).
          Last edited by J.P.M.; 09-19-2017, 12:01 PM.

          Comment


          • #20
            Originally posted by J.P.M. View Post
            I'm calling B.S. on it (again).
            What part of "bite a rock" don't you understand?

            I could put "for entertainment purposes only" on posts about pie-in-the-sky stuff, if that'd make you feel any better. The post was already dripping with disclaimers, but a few more wouldn't hurt.

            BTW here's the other paper linked to from the article (for entertainment purposes only, of course):
            pnnl.gov/main/publications/external/technical_reports/PNNL-24904.pdf

            Even if the idea is old, it may be time to dust it off and see if it makes sense today; the economics may be rather different now than they were last time around.
            Last edited by DanKegel; 09-19-2017, 11:33 PM.

            Comment

            Working...
            X