When I first heard about using particle accelerators
to create solar panels, I thought… what?! I must not understand how solar panels are
made. Or how particle accelerators work? And yes, there’s a key, unglamorous step that
– unless you’re fairly familiar with solar manufacturing technology (which I’m not)
– you probably wouldn’t think of, and it’s in this step where a particle accelerator
turns out to be useful: cutting silicon into the really thin wafers that are the key component
of a solar panel. However, even this wasn’t at all what I
first thought, which was something like slicing through the crystal with a super powerful
particle beam. That sounds awesome, but the actual technique is much less insane and much
more clever. Ok, so a typical solar panel cell begins as
a carefully grown cylinder of silicon atoms arranged in a regular crystal lattice, which
are then trimmed and cut into wafer-thin…wafers. Some of which retain curved corners as hallmarks
of the original cylindrical crystal.
Then the wafers get covered with other metals,
anti-reflective coatings and electrodes, and so on, to be able to capture the sun’s energy
– but the part we want to focus on is the cutting. Because when you cut something with
a saw, like silicon wafers normally are, there are two problems: one, you can't cut a slice
too thin otherwise it might get broken – typical solar panel wafers are cut to about 0.15 millimeters.
And two, unlike a knife which cuts by separating and wedging two pieces of material apart,
a saw cuts with teeth that gouge and eat away at the material, turning it into saw-dust
and leaving a gap called a kerf. In the case of silicon wafers, the gap is roughly the
same width as the wafers themselves, which means about half of the original material
goes to waste! This is where particle accelerators come in: not
as a high powered ablative cutting particle beam, but by taking advantage of the physics
of crystals. If instead you shoot protons with a certain energy at the flat face of
the silicon cylinder, those protons will embed themselves into the silicon. The depth depends
on how much energy they have, and the thinner you want, the less energy they take, so you
can easily pick something super thin.
But whatever thickness you choose, once inside
the silicon crystal lattice, the protons kind of push it apart and create stress; if you
heat the whole thing up, a wafer will break right off, cleanly cleaving along the crystal
lattice lines where the protons were. So, if after the protons are embedded, but before
the heating, you glue this proto-wafer onto a piece of glass or plastic, and then heat
it up, you end up with a nice thin wafer of silicon attached to a durable (and possibly
flexible) material, with no waste silicon whatsoever.
To me, this is clever physics
engineering! Of course, a particle accelerator is much
more expensive than a saw, so there must be some upsides to it – the biggest is that,
by using significantly less silicon per wafer and not losing any silicon in the cutting
process, it’s possible to justify using much more expensive silicon that’s better
at capturing sunlight, meaning the resultant solar panels for a given power output are
smaller and need less other material to make them and hold them up, hence they’re cheaper.
Hopefully enough cheaper to make up for the extra costs of using a particle accelerator
to part silicon! The company that’s trying to use the particle-accelerator
technology I talked about in this video to make solar cells on a commercial scale, this
company is called Rayton Solar. This is a challenging and expensive endeavor and they’re
looking for investors, so they sponsored this video to get the word out – startengine.com/startup/rayton-solar.
I’m not going to make any endorsement – I mean, I’m neither an investment expert,
nor a solar industry expert – but I do believe strongly that we need both political and technological
solutions to secure our planet’s energy future, so I’m happy to help Rayton reach
a broader audience to help give them a chance for this clever idea to succeed, and I’m
making a small investment myself.
Hopefully they’ll end up being one of the many many
pieces that come together to provide a civilized long-term future for humanity on earth..