This video is brought to you by Brilliant.
There’s always the promise of some big breakthrough that’s going to change everything.
Well, scientists have just smashed the solar panel efficiency record, and it could mean a
big change for the future of renewable energy. This isn’t just more hype, but a sign of
where things stand today and are heading. However, this isn’t the only big
solar news from 2022. There’s been a lot of very recent advancements from
perovskites to organic solar cells too, so what does this mean for you and me? Let’s
see if we can come to a decision on this. I’ve covered a lot of solar panel
news over the past few years, as well as my experience with
my own solar panels on my home. Solar power is practically the grandfather of
the renewable energy family, and for good reason: there’s a limitless energy source shining down
on us literally every day, just waiting to be harnessed. Just one hour of power from the sun is
more than the entire world uses in a year! It’s why I’m so fascinated by it, but the big downside
is that we can’t capture all of that energy. Along those lines, many people
leave comments that basically say, “solar panels aren’t efficient enough,” and most
likely, “never will be.” That line of thinking always surprises me because the technologies we
all take for granted today were the breakthroughs of a decade ago, so the breakthroughs
of today are where things are heading. In just the last few months, we’ve seen
some exciting advancements in solar, some that we’ve been waiting for nearly ten years
for. So if you’ve been holding off for the right benchmark–perhaps a target efficiency rate, or
the right type of material to get into commercial use–your wait may be over, but let’s run
through some of the more interesting updates, as well as some of the gotchas
and what it means for us. First, we have to talk about some of
the biggest news on the solar front, and that’s the fact that the US Department of
Energy’s National Renewable Energy Laboratory just set a new solar cell efficiency record
of 39.5%. This was accomplished under similar lighting conditions to the sun, which is
a stark change from the last world record. Earlier experimental solar cells showed
top efficiency rates of 47.1% in 2019, but that was only when exposed
to extremely concentrated light. So how did they do it? Rather than adding
more light (like the last record did), NREL’s record-breaking cells use inverted
metamorphic multijunction (IMM) cells. These cells have three layers stacked on top of one another,
each made of a different material: gallium indium phosphide on top, gallium arsenide in center,
and gallium indium arsenide on the bottom. Each soak in a different range of light wavelengths,
which lets the cell capture more energy from the whole light spectrum.You can also find three
hundred “quantum wells” in the middle layer, which was the key to unlocking these cells’ new
efficiency rate These wells extended the bandgap in the cell, which increased the amount of
light that the cell could absorb overall. NREL isn’t the only one who's had success
squeezing out more energy by tweaking their solar cell design. A team co-led by the University of
Surrey increased the amount of energy absorbed by their wafer-thin photovoltaic panels by 25%. The
panels themselves are only one micrometer thick, but they’re made with a honeycomb-esque layer that
allows for light absorption. In silicon cells, nearly ⅓ of the light that hits the cell usually
bounces right off, but the textured design of these thin photovoltaic cells traps the light
in the solar cell to increase the efficiency. This design was inspired by nature
-- butterfly wings and bird eyes already do this to some degree. In the lab, the
team saw absorption rates of 26.3 mA/cm2, a 25% increase on the previous
record of 19.72 mA/cm2 in 2017. The efficiency rate isn’t too shabby, either:
these cells have an efficiency rate of 21%, with the expectation that further
tweaks will nudge that number higher, possibly even higher than other
commercially-available photovoltaics. Solar panels usually go hand in hand
with silicon (which is used in 95% of panels in today’s market), but there’s
been a lingering beacon on the horizon of the solar world: perovskites. I’ve
touched on these in previous videos. Perovskites are a group of synthetic materials
that are defined by their crystallographic structure. In general, they easily coat surfaces,
which means that they can be used in cells on their own or in tandem with other technologies
(like our existing crystalline silicon cells). These perovskite semiconductors can convert
the energy-rich blue spectrum of sunlight into energy, so when used in
tandem with silicon sub-cells, we can get efficiency rates of up to 30% (compared
to 25% in single-junction perovskite cells). Perovskites are meant to be the golden trio:
cheap to produce, competitively efficient, and thin and lightweight enough to apply
practically anywhere. That’s why researchers have been chomping at the bit to get them on
the market, but there have been a few logistical hurdles before perovskites could attempt to
give silicon cells a run for their money. The first problem is one of perovskite’s biggest
hurdles: the durability factor. Perovskite cell’s thin and light nature are a perk, but it also
means that they’re fragile, which is not great for a material that is going to be pitted
against rain, sun, hail, and everything in between. Samples used to break before researchers
could even make it across the lab to be tested! If the samples cannot be handled in the laboratory,
they cannot withstand the occasional hailstorm or stresses applied by wind loading and torsion
on the solar panel frame in the real world. Thankfully, they’ve come a long way since then.
An April study found that organometallic compounds could be used as an additive to help improve the
cells’ lifespan, efficiency, and stability. The enhanced cells maintained 98% of the cell’s
original 25% power conversion efficiency rate after 1500 hours of use, and they also passed
the damp heat stability tests with flying colors. Researchers have also been diving deeper into why
perovskite works like it does, both the good and the bad. In May 2022, scientists at Cambridge
University and Japan’s Okinawa Institute of Technology (OIST) used imaging techniques to
observe the structure of perovskite films at the nanoscale, especially when light actually
hits the film. They found one of the culprits behind perovskite’s infamous photodegradation
problem: nanoscopic trap clusters. These are defects in the material that show up as pockets
from the cell processing, which ultimately make the film less efficient and structurally fragile.
The main way to combat these efficiency-limiting carrier traps is to remove them during the
manufacturing process through careful tuning of the structural and chemical design. Make
these tweaks large-scale-friendly, and you have a recipe for making more of these films while also
making them better in the performance department. What if making new solar cells was
as simple as printing a newspaper? That’s what the producers of organic
power cells hope to accomplish, and as of now, they’re ready to push
this tech into the worldwide market. Organic power cells are made by printing
photovoltaic material onto flexible materials like plastic sheets. These paper-thin solar
cells are composed entirely of organic materials: flexible, lightweight, and quick to
manufacture with printing technology (the same process as printing newspapers!) They
cost half as much to make as silicon-based cells, and they’re also 100X lighter. Each
square meter weighs less than 2 kilograms, and that’s likely to dip
down to 1 kilogram in 2023. Unlike silicon cells, their conversion efficiency
rate doesn’t drop when used indoors, which makes them extra appealing for devices like smart
speakers, sensors, and other wearables that may not get to see a lot of actual direct sunlight.
This makes use of existing ambient light, converting some of it to electrical power reducing
the load on small batteries and charging devices. The efficiency rate leaves a
little to be desired at 10%, but these cells can also be used for around
20 years, which already dwarfs the current perovskite lifespans (more on that later). As
more businesses start to ramp up production, that mass production has the
potential to cut the costs in half. These “print-to-order” solar cells are
starting to hit the market on a global scale. German startup Heliatek is beginning
mass production of organic solar cells as early as this year, with a goal to produce
600,000 square meters (and a max production capacity of 1.1 million square meters a year!)
Brazilian startup Sunew also has these organic cells in production, producing over 10,000
square meters of organic solar cells so far for vehicle rooftops (since they’re
big electric-vehicle fans). Sweden’s Epishine put its miniature solar harvesting
modules on the market just this past December, boasting an energy-conversion rate of 13%
and a lifespan of 10 years. These can be used for temperature and humidity control sensors,
fire alarms, card readers, and other small–yet important–devices that often blend into the
background. And then you have Ricoh in Japan, starting on a smaller scale. They only produce 100
square meters a year, but that’s enough to power 50,000 small smart devices, from wearables
to safety sensors in tunnels and bridges. Even these cool cells have room to
improve, and researchers have found two key developments with the potential to
really help organic cells capture that spark. Strap yourself in, we’re going to get
real nerdy in here. Let’s talk chirality. DNA (and other helix-shaped molecules) are
considered chiral. That design is everywhere in nature, and it’s key to practically everything
from our genetic makeup to photosynthesis. They’re asymmetrical, and as electrons go
through the structure, they separate charges created by the light (meaning that light can be
converted into biochemicals more efficiently). Now usually, molecules stay with
their own structural cliques … it’s kind of like high school … (chiral
with chiral, achiral with achiral, etc). However, researchers at the University
of Illinois Urbana-Champaign found that when they applied achiral conjugated polymers with
a solvent, the solution eventually evaporated to leave behind reassembled polymers: more
specifically, helixes, aka, chiral structures. Going from achiral to chiral
structures is a pretty big deal, especially when it comes to applying the
idea towards organic solar energy. In theory, scientists can apply that chiral structure (and
all the energy-producing goodness that comes with it) to materials that normally require achiral
conjugated polymers to function, like solar cells. Secondly, let’s talk about everyone’s favorite
subject: perfluorinated sulfuric acid ionomers. (No? Just me?) Let me explain: to make
fully-printable organic solar cells, you need hole-transporting materials. That’s hole,
not whole … you gotta love the english language. These are HTMs for short. One such promising
HTM has been PEDOT:PSS, a conducting polymer complex that is used to make printable
devices. It’s been around since the 1990s, but it’s falling short today. Unfortunately
it disperses in water and is very acidic, which can impact the efficiency and
stability of the PEDOT:SS-based solar cells. To combat this, researchers at Huazhong
University of Science and Technology and the Institute of Materials for Electronics
and Energy Technology (i-MEET) have come up with PEDOT:F, a new polymer complex that
disperses in alcohol and has low acidity. With this new formula, organic
photovoltaics have been shown to have a power conversion efficiency of
15% and retained 83% of their initial efficiency under constant illumination at
maximum power for a total of 1,330 hours. These new solar developments may not be the
most attention-grabbing to the average person, but they are a clear sign that there’s still
more to solar energy on the horizon. So what can we actually take from these developments,
and what does it mean for the industry at large? First, as exciting as breaking the
world record of solar efficiency is, NREL’s solar cell design still has its own
disadvantages. For one, producing this type of cell is still going to be expensive at this
point, which is a problem that already hobbles the renewable energy industry at large. Mass
producing cells with this level of efficiency may still be a long way off, and we would
need to find a way to do so while keeping the overall costs low enough to not
price major consumers out of the market. The University of Surrey’s honeycomb design,
on the other hand, seems to target that problem directly. These cells use less silicon overall,
which translates to cost savings in the production process. There’s a lot of potential to how we
can use them, too: even while textured, the film layer is still super thin, which makes them light
and versatile enough to go practically anywhere! The next step is to get the show on the road
by finding commercial partners and developing manufacturing techniques. As you may have
guessed, that’s no small feat in itself, and for now, this design is
still a long way from the market, an unfortunate fate for many promising
renewable technologies in the making. So how about perovskites, the solar industry’s
shining beacon and simultaneous problem child? Perovskite cells are finally on the market
now, but they’re nowhere near where fans hoped they would be, and they’re definitely
not over the commercialization hurdle just yet. A lot of this can be attributed
to their fickle nature in the field. Both silicon and perovskite solar
cells have set records above 25% recently, so the power itself isn’t
necessarily the problem: it’s the endurance. Unfortunately, perovskite cells in the field
lose 10% of their cell’s efficiency after a few months of use. When you compare that to
silicon cells–whose manufacturers guarantee that panels will maintain 80% of their
performance for sometimes 30-40 years–that’s a tough act to follow. Perovskite cells need
to last at least 20 years in the field to meet the US Department of Energy’s Solar Energy
Technology Office (SETO) 2030 goals of $0.02/kWh. Manufacturing will likely be the final major
hurdle to commercializing perovskite solar panels. It’s a bit of a catch 22: we need financing
to scale up manufacturing and develop cells at large scale, however, financing will only
be available when the scale up looks feasible. Here’s the good news: perovskites
don’t HAVE to outshine silicon cells. You can also use them in tandem cells,
where a perovskite layer is stacked on TOP of a silicon cell . (Talk about the best
of both worlds!) The materials absorb different light wavelengths, which means
you get complementary energy harvesting. So how about organic cells? The idea itself is
still pretty attractive. These types of cells could use their lightweight and flexible nature
pretty much anywhere, from domed roofs, glass, and other oddly-shaped surfaces that couldn’t
support the heavier silicon-based panels. These guys probably won’t be powering your
neighborhood anytime soon, but they have found their own special niche: specifically,
smaller devices, including wearables. Why are wearables such a big deal? Most
use single-use batteries that need to be replaced every 1-2 years. That’s a big deal for
this segment when the global market for smart sensors alone is expected to reach $29.6 billion
in 2026, according to MarketsandMarkets. Current solar tech doesn’t quite cut it
for these smaller applications yet, as silicon doesn’t work as well indoors, and
perovskite cells only last a few years at a time. True, their efficiency rate is
still a little skimpy (at least, compared to their other solar counterparts).
Hopefully, further studies into chirality and other polymer solutions may help boost
that efficiency rate in the long run, making the “printable solar cell”
a staple in the solar community. While we’re most likely still a few years away
from seeing these admittedly cool developments actually make ripples on the market, it’s a
clear sign of where things are heading. However, if you’re considering solar for your
home, don’t wait. Solar panels are efficient enough today to achieve a lot of
the goals you probably have for your home. Waiting for the next big thing pretty much
ensures that you’ll always be waiting … because there’s always something better around the
corner. If you live in the US, don’t miss out on the current Federal tax solar rebate,
which will be dropping at the end of the year. You can use my EnergySage portal (link in
the description) to help research and get quotes from installers in your area. I used
EnergySage to research products and find my own installer for my house and absolutely
loved the experience. Don’t wait and miss out. If you’d like to learn more about
the science behind solar panels, I'd strongly recommend checking out Brilliant.
They have fantastic interactive courses, like the Scientific Thinking course. But if
you really want to get your head wrapped around some of what we covered with these solar
panel breakthroughs, be sure to check out the Solar Energy course. It walks you through
everything from EM Basics to solar panel band gaps. The course was created in collaboration
with an MIT mechanical engineer and researcher. I’ve been working my way through that one and
am really enjoying learning at my own pace. If you get stuck, Brilliant will give you in-depth
explanations, which helps you understand the “why” and “how” of something. And you’re learning
the concepts by applying them through fun and interactive problems yourself. I’ve found this
active learning is how I learn best. Join over 11 million people learning on Brilliant today.
Go to https://brilliant.org/Undecided to sign up for free. And also, the first 200 people will
get 20% off their annual premium membership. Thanks to Brilliant and to all of
you for supporting the channel. So are you still undecided? Do you think these
advancements are a good sign of what’s to come? Jump into the comments and let me know and
be sure to check out my follow up podcast Still TBD where we’ll be discussing some
of your feedback. If you liked this video, be sure to check out one of these videos over
here. And thanks to all of my patrons for your continued support and welcome to new supporter
+ member P W, and producers Jessica Nash, and Oliver Hilton. And thanks to all of you
for watching. I’ll see you in the next one.
