5 Inventions Showing Us the Future of Solar Energy

[♪ INTRO] When you imagine the energy of the future,
solar power is probably in the picture. After all, it’s reliable, it is powerful, and it fuels the vast majority of life on
Earth. In recent years, less than two percent of
the world’s electricity has come from solar power—but new inventions are likely to change that. So here are five ways solar energy could help
power the future. You might think that vast, arid deserts are
the perfect place to install solar farms. After all, desert sunlight is intense, and
you don’t usually have to worry about clouds. Plus, there’s plenty of wide-open space. But there is one problem: Solar panels aren’t
fans of heat. Solar panels work by converting light directly
into electricity: When they absorb sunlight, that energy knocks
electrons loose —and those loose electrons create an electrical
current, which can be captured and transferred to a
wire. The thing is, solar panels do that most efficiently at temperatures under 25 degrees Celsius. That’s because, when the solar panels get
hot, the electrons pick up that extra energy from
their environment, which puts them in a more excited state.

And when they’re already excited, they have
less room to absorb energy from the Sun. So, they actually work best in moderate climates—where, unfortunately, it can sometimes be hard to
find the space to set up a giant field of solar panels. But since the 2000s, countries around the
world have been implementing what seems to be a win-win solution: a system
called agrivoltaics. In agrivoltaics, solar panels get installed
over crop fields. That way, there’s no need to clear extra
space just for the panels, and, on top of that, the crops help keep things
cool as they release water through their leaves. That release of water works just like sweating: Evaporating water removes heat from a plant,
which brings down the plant’s temperature and also cools the
surrounding area. So it can help keep things nice and balmy
for the solar panels. And it makes them noticeably more efficient! Researchers centered at the University of
Arizona found that, between May and July of 2019, solar panels
over croplands were three percent more efficient than solar
panels in the same region that were not over croplands.

That might not sound like a lot, but over
time, those small gains add up. For a house or building operating on solar
power, it would amount to close to three days’
worth of electricity over those three months. Engineers have also extended a similar concept
to a setup called floatovoltaics, in which floating solar
panels are placed on bodies of water, which are also
typically cooler than the air and help keep the panels cool
and working efficiently.

As an added bonus, agrivoltaics and floatovoltaics
also open up lots of new possibilities when it comes to
finding space for huge arrays of panels. Setups like these already exist all around
the world, and they’re becoming more popular. If that continues, agrivoltaics and floatovoltaics
could produce a significant fraction of the world’s
energy in the future. Engineers are always trying to get as much
energy out of solar panels as they possibly can. And one of the things they have to think about
is exactly what direction a panel should be facing. See, solar panels produce the most energy
when the Sun’s rays are hitting them head-on, rather than
at an angle.

So, traditionally, people have installed these
panels at a fixed angle that gets the most direct
sunlight at their specific latitude. But that’s not a perfect solution, because
the angle of the Sun’s light is always changing depending
on the time of day and the season. That’s why engineers invented something
called photovoltaic trackers, or PV trackers. PV trackers move solar panels along tracks
that follow the arc of the Sun. The trackers make sure that the Sun’s rays
are always hitting the panels head-on, so they’re always
performing at their peak. To run, these systems do use about 5 to 10
percent of the energy they produce, but the energy gained outweighs
those losses. In fact, these mounts can boost the amount
of electricity a solar panel generates by up to 45 percent, depending on the geographic location. In places far from the equator, where the
angle of sunlight varies significantly between summer and winter, PV
trackers can be especially useful. They’re generally still too heavy to be
practical on rooftops, which have to be structurally reinforced to
carry something so heavy, but they are being used in other settings.

Today, most solar panels have a pretty conspicuous
look, and they don’t just naturally blend into
their surroundings or the architecture they’re attached to. But there’s only so much you can do about
that because the most common solar panels are made of silicon, which is just naturally bulky and heavy. Silicon is great for turning light energy
into electricity —since its electrons are arranged in a way
that makes it easy for sunlight to knock them loose—but it’s
not the only option. Some engineers are exploring alternatives, including solar cells that could be embedded
right in your windows. Like, the idea is that you could be sitting
by a window on a sunny day, and there’s light and warmth
hitting you. But some of that sunlight could also be converted into electrical energy… right in the glass. But for that to happen, solar cells would
need to be made of something way lighter than silicon and also something partially transparent.

Scientists actually found a way to do that—by
developing a new type of solar cell made of organic compounds. These organic solar cells are made of thin
layers of materials like polymers and dyes that absorb light and
turn it into electricity, a lot like silicon solar cells. But they can be made by printing the dyes
onto thin materials, like rolls of plastic—or glass, in the case
of windows. Now, by definition, a material that’s absorbing
light is usually pretty opaque, but organic solar
cells can be designed to absorb mainly infrared light, letting visible
light pass through. So, these days, organic solar cells are
fairly transparent. They let through about 43 percent of light—which
is pretty dark compared to the windows in your home, but
they could make a nice tinted window for an office building. What’s great is that cells like these are
cheaper and easier to produce than silicon cells,
and since they’re so lightweight, they could eventually
be adapted for phone screens, camping equipment, or car
roofs. There is a small catch: They’re not nearly
as efficient as silicon. They only convert about 13 percent of the
Sun’s energy into electricity, whereas silicon cells typically
harness about 18 to 22 percent.

Still, the fact that they’re so easy to
apply means they could be installed in a greater number of
places —including places that don’t currently
generate any electricity. In the future, buildings might not be the
only things decked out in solar cells—because now, researchers
are working on solar fabrics, textiles that would have solar cells integrated
into the fibers. The end goal is to generate electricity just
by walking outside. One method researchers are experimenting with
is creating super-tiny solar panels that can be embedded
into fabric. In 2018, researchers in the U.K. created solar
cells measuring 3 millimeters by 1.5 millimeters—basically
the size of a flea. Then, the tiny panels were embedded into yarn that was woven into clothing. The idea was for the panels to be small enough that the person wearing the clothing shouldn’t
feel them. To test their invention, the researchers embedded
200 cells in a prototype—and they were able to generate
enough energy to charge a Fitbit. So we’re not talking like a huge amount
of energy here, but with just 2000 cells, you could hook up
your smartphone with a wire and make enough electricity to
charge it.

Believe it or not, the design is actually
pretty subtle, too. Other fashion designers have incorporated
solar panels into fabric in the past, but they’re usually pretty
noticeable… which tends to turn people off. Unless you want to put on like a cool mask
and really awesome jeans and then like rollerblade like it’s cyberpunk
times. Not all solar fabric has to be wearable, though.

Other companies have successfully embedded
solar cells into heavy textiles used for things like awnings
and canopies, which have the benefit of actually sitting
out in the sun all day long, too. Finally, most recent inventions related to
solar energy have focused on creating electrical energy,
but some researchers have taken a different approach: They’re
focusing on using the Sun’s energy for thermal power, the
kind of thing that heats our homes.

The goal is to create a rechargeable battery
made of chemicals called solar thermal fuels. Solar thermal fuels absorb the Sun’s energy,
store it in chemical bonds, and then release it as
heat at a later time. And they can do that on command. When these fuels absorb sunlight, that new
energy disrupts the chemical bonds in the molecules
and causes them to rearrange into a new configuration. Now it always takes energy for molecules to
form chemical bonds with each other, and this new configuration
takes more energy —so it traps all the energy the fuel has
absorbed from the Sun, and just holds onto it. Like, researchers in Sweden developed a fuel that can store solar energy for nearly two
decades. But, as soon as you want that energy back,
you can pass those molecules through a physical filter
that acts as a catalyst to rearrange those molecules back into their
original configuration—and release all that pent-up
energy as heat.

In fact, the team in Sweden got the fuel to
bump the temperature of its immediate surroundings by 63 degrees
in just a few minutes. And the team is hoping to get that number
even higher. So the idea is to develop a fuel that can
release enough energy to heat a home. And if the technology can get there, it sounds
like a pretty great deal: The fuel would start on the roof of your home, where it would absorb sunlight. Then, when it was time to turn on the heat, the fuel would pass through that filter, and
the molecules would release all the heat they’d stored. The whole process is emissions-free, and the fuel can be reused over and over. These days, solar technology is about way
more than just solar panels, and while these inventions take time to develop
and make their way into our lives, they show a lot of promise
for a solar-powered future.

Thank you for watching this episode of SciShow! And a special thanks to this month’s President
of Space, Matthew Brant, for helping make this episode
possible! If you’re interested in joining our amazing
community of supporters helping us make science education free on
the internet, you can find out more at patreon.com/SciShow. [♪ OUTRO].

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