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.