• EEVblog #846 – Solar Panel Micrometeorite Impact!

    Dave uses a microscope to examine the shattered LG Mono-X solar panel. Was it a micrometeorite impact?
    And what are the odds of a micrometeorite impact on a typical solar power installation in a given year?

    Forum HERE

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      • Aeroplane frozen jetson?

      • tkj tkj

        Interesting!! It reminded me of how important is the ‘sharpness’ of small objects as they hit glass surfaces ..
        I found this demo of a fellow who created small shards of the ceramic insulator from an ordinary engine sparkplug, shattering
        the ceramic with a hammer .. He then, without much force/velocity threw an approximately 1″ shard at a car window
        with am impressive result! :
        https://www.youtube.com/watch?v=QhlmKHbPFhU

        Then see:
        https://www.youtube.com/watch?v=llu-ckEe5cQ

        and finally (importantly!.. with a practical application! ) :
        https://www.youtube.com/watch?v=WRbR2fynp1o

        a different effort by another individual using a ball-bearing or even an entire sparkplug was repulsed by the glass !

        Of course these ‘tests’ or ‘demo’s were not conducted with any semblance of ‘statistical validity’ but at the same time
        they might suggest that the very material of the object hitting tempered glass is related to damage caused.

        Thanks , Dave , for a great investigation and presentation too!! as always!
        tkjtkj

      • Seth Tucker

        I think a meteorite is far more likely than a micro-meteorite. The atmospheric drag on a micro-meteorite is going to be huge, so I don’t think there’s any way that it could have enough energy to do any real damage without vaporizing long before it hit the surface.

        For reference, this Wikipedia image from Wikipedia shows shingle damage from a 61.9g meteorite. https://en.wikipedia.org/wiki/Meteorite#/media/File:Novato_Meteorite_Impact_Pit.jpg

        • Yes, meteorite instead of micrometeorite (which wouldn’t have the impact velocity required). Someone has shown it to some meteorite experts and they agree it’s likely golfball size or maybe greater, hitting on a sharpish point.

      • DeniTCH

        The size of the impact looks similar to the actual micro-meteorite impacts on the Hubble telescope solar arrays (see attached picture). Of course the Hubble solar arrays don’t have tempered glass for the nice pattern 😉

        Edit: the picture did not attach, I hope that the link works: http://imgur.com/lc56jDw

      • Fireballs in the Sky

        Great question Dave! and thanks to Per Öresjö – @ikeraliR for the ping.

        Our meteorite experts answer your question: http://fireballsinthesky.com.au/2016/01/has-this-solar-panel-been-hit-by-a-meteorite/

        • Syd Jessop

          Doesn’t the impact pattern on the back of the panel strongly indicate against a cricket ball?

      • Alex

        There is only way way to know 🙂 Hit another cricket ball into this thing!

      • 4z4tj

        in order to find out what the embedded particles are I suggest check local universities and interest a researcher with access to a SEM with XRD …

      • Syd Jessop

        Come on, Dave, it is clearly one of your Batteriser buddies who has climbed up onto your roof and whacked your panel with a pick axe. It is no co-incidence it was the panel on the end. I mean, it’s obvious, isn’t it?

      • Tracy Gilmore

        Sure it wasn’t some visiting U.S. Policemen? They tend to shoot their weapons off a lot.

      • 年前再来转转!

      • Blakael

        Could it be a broken branch or stick? I’ve seen a branch go straight through a roof tile, broke it in half, and through the ceiling. Those brown particles look like it could be bits of branch.

      • Erik Hovdahl

        You got the rest of the panel, why not test it by trowing different things

        into it, like a smal stone, a ice bit, a golf ball… and compare it..

        • Because the entire panel is already shattered, every square inch of it.

      • essnam

        Hello Dave thank you
        very much for the very nice investigation and analysis. Although I followed
        your evidences but arrived to a different collision. As you put some time to investigate
        this problem, I thought that it is not bad idea share my analysis with you. Let
        me explain. The speed of a micrometeorite
        should be at least equal to bullet fired from a gun to cause such an impact
        into your solar panel (60-100m/s for a 30-calibre or ~7.8mm diameter bullet https://en.wikipedia.org/wiki/Celebratory_gunfire#cite_note-isbn1-58890-308-7-8 ). Normally a micro size particle falling under
        the gravitational field of the Earth, like rain droplet, will reached to a terminal
        velocity soon due to air resistance forces. This is about a speed of few meter
        per second (see e,g, http://www.shorstmeyer.com/wxfaqs/float/rdtable.html
        ) which definitely incapable to do any harm to the panel. The terminal velocity
        of skydiver of mass 75kg is 60m/s (http://hyperphysics.phy-astr.gsu.edu/hbase/airfri2.html
        ). This rules out a micrometeorite high speed impact. The second and very
        unlikely possibility would be a big meteorite that was falling with much bigger
        mass and therefore a much bigger speed which was burning during the fall so losing
        mass to a micrometeorite as falling and hit the panel surface. In that case at
        least part of the total kinetic energy should be transferred to heat as particle
        comes to rest in the panel and leaves a trace as residuals. This is also not
        seen in your panel. By ruling out of a micrometeorite collision, the only possibility
        left is with a no residuals and heat effect could be the effect of a sharp object
        like a nail that hammered into the panel! thanks Essnam

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