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
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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.