Ok yes, solar panels are great. But there is a more efficient technology than your average PV cell. And that is this

These are peroveskite solar cells, promising to unlock PV cell Efficiencies 100% higher than current comercial cells

But here’s the thing, the reason why we don’t see them in our houses today. Is that at worst the last a couple of days and at best will barely last a year! And that is under lab conditions. 

But that’s about to change! Recent breakthroughs in perovskite synthesis increase cell lifetimes by orders of magnitude, and at least one company seems to have cracked the durability problem and will release the first commercially available perovskite solar panel this year!

What does this mean for you and me? Let’s figure it out together. I’m Ricky, and this is Two Bit da Vinci.

This is a solar panel, you’ve seen this before. Early solar panels looked like this (poly crystalline), but now they look like this, and now they even come in dark mode. But all these panels are made of silicon, most solar panels are. But there’s a new kid on the block, called Perovskites, and it’s been on the brink of revolutionizing solar panels for some time now. Perovskite isn’t an element like Silicon but instead refers to a family of materials, which have some unique properties. Like being, easier to produce, lighter weight and more efficient. But they have a major problem, they don’t last very long. Kind of important for a solar panel. But recent breakthroughs in perovskite synthesis could change all that. In fact one company seems to think they’ve cracked the code and plan to have a commercial perovskite solar panel later this year. So just how big a deal is this? Let’s figure this out together, I’m Ricky and this is two bit da vinci.

Perovskite solar cells promise to unlock PV cell efficiencies 100% higher than current commercial cells. But they have a huge problem: They’re unstable, and even the best cells will barely last one year under lab conditions while dirt-cheap solar panels today can last over 30 years.

But that’s about to change! Recent breakthroughs in perovskite synthesis increase cell lifetimes by orders of magnitude, and at least one company seems to have cracked the durability problem and will release the first commercially available perovskite solar panel this year!

What does this mean for you and me? Let’s figure it out together. I’m Ricky, and this is Two Bit da Vinci.

Efficiency in context — Why does it matter?

(clips of solar panel commercials)

A typical solar panel, like the one you can buy today for a couple hundred bucks, has a Power Conversion Efficiency of around 20%.

• That means that for every 100 watts of solar energy that hits the panel, only 20 watts get converted into electricity.
• Those panels are made of silicon, the same semiconductor in computer chips.

But a new type of panel with perovskite solar cells is about to hit the market with a 25% efficiency.

• That doesn’t seem like much of a difference. Does it?
• However, this small increase could slash the cost of a system like the one I have installed at home from $30,000 to just over $20,000.
• We’re talking about an almost $10,000 difference!
• This is huge!
• How many of you haven’t decided to install solar at home because of the high upfront cost?
• Wouldn’t the possibility of saving almost $10,000 impact that decision?
• Hit pause and sound off in the comments!

Now, that’s only the tip of the iceberg of what perovskites promise for solar, but we’ll go back to that in a minute.

• First, I know you’re probably wondering how can such a small change in efficiency make such a big difference in cost.

I figured this out by asking myself, what would change if, instead of 20% efficient panels I had bought cheaper panels with 25% efficiency.

• I had to install 30 400-watt panels for my 12 kW system. 

(Show aerial footage of your house’s PV setup)

• If I had used 25% efficient panels, I would have only needed 24 of them for the same 12kW system.

(Show a schematic of your roof with 30 panels working at 400W with a label of 20% efficiency and the system total of 30 panels x 400 W = 12,000W. Then show the same roof with only 24 panels, each working at 500W with a label of 25% efficiency and the system total of 24 panels x 500 W = 12,000W)

• And if the panels are even cheaper than the ones I bought, well…

• I’ll leave it at that for now and share the specific numbers in a moment.
• For now, what matters is that perovskite cells are more efficient than typical silicon cells, so you need fewer of them, and they’re also much cheaper to make.
• Both things work in tandem to save you money.
• A win-win!

(Show the following text: Perovskite Panels = Higher Efficiency = Fewer panels X lower cost per panel = Huge cost savings on the system)

The big problem with perovskite cells

So, why aren’t perovskites everywhere?

You guessed it!

Because there’s a tradeoff:

• The oxygen and moisture in the air, the heat, and the sun’s UV rays all work together to destroy perovskite cells.
• Yes, it’s kind of ironic, isn’t it?
• Sunlight itself breaks down perovskite solar cells, sometimes in a matter of months or even days
• Compare that to my silicon panels which will work uninterrupted for 30+ years while keeping 90% of their original performance!

In fact, now that I think about it, it’s a freaking miracle that a solar panel can last that long! Don’t you agree?

• I challenge you to name one thing besides your house that can last over 30 years under the sun with minimal to no maintenance.
• Not even your shingles. Most of those last 15 to 20 years!!
• The point is, we need to fix perovskites’ durability problem.
• Apparently, that’s a tough challenge, although one company from the UK says they solved it.
• We’ll talk about it in a moment, so don’t you dare click out. You won’t want to miss this.
• I first set out to understand why, starting with figuring out what the hell are perovskites, anyway.

What are perovskite solar cells

• Perovskite solar cells are a type of solar technology that uses a family of materials called perovskites to convert sunlight into electricity.
• These perovskites are materials that have a similar structure to a mineral made of calcium titanium trioxide (CaTiO₃) called perovskite in honor of the Russian mineralogist who discovered it.

(Image of a sample of perovskite and its discoverer Lev Perovski)

• This mineral forms little cubic crystals that look like this:

(Perovskite structure)

• Any material with the general formula ABX₃, and whose crystal structure looks like this, is a perovskite.
• A, B, and X can be almost anything, so you can tweak these materials by changing the ions in the formula and fine-tuning them for different applications.
• One of those applications, is solar cells, with most of the research in the last ten years focused on lead halide perovskites [MIT] with record-breaking efficiencies. This is important, so keep it in mind.

• That said, these efficiencies are worthless if the cells don’t last.
• Which brings us back to the durability problem.
• But if you’re watching this, you probably guessed that there’s a solution.
• Enter, the new breakthroughs in perovskite degradation.

The solution — Breakthroughs explained

There are several ways engineers have tried to solve the durability issue.

• The most straightforward has been to encapsulate the cell to protect it from the environment.
• But that only solves part of the problem.
• Another important part of the issue has to do with the internal structure itself, and nothing to do with the air or sunlight.
• You can’t fix this by encapsulating the cell.
• Two recent discoveries helped increase cell life by orders of magnitude.

Eliminating surface concavities

• The first discovery was made by Yuanyuan Zhou and his team from the Hong Kong University of Science and Technology and was published in Nature Energy.

(source)

• They looked closely at the tiny little crystals with an electron microscope and discovered they had a secret structure no one had ever noticed before:
  • They were covered with little concavities.
  • These are like little indentations that strain the crystal structure making it unstable.
• The breakthrough is that they figured out a way to make the perovskite material from scratch without these concavities.
• All they had to do was to add a type of surfactant, something like a detergent whose name I won’t even try to pronounce, and bingo! 
• The concavities were gone!
• The resulting cells lasted 1500 hours under different stress tests, compared to only 500 hours before.
• Ok! Before you say anything! 1500 hours is just two months under sunlight, so just around 4 months in the field.
• Not a lot by any measure.
• But it’s still a three-fold increase, and it’s not the only breakthrough.

Eliminating internal defects in the crystal structure

The next breakthrough came from the same research team and was also published in Nature.

• In this case, they looked at the perovskite’s internal structure instead of the surface.
• They found that the little crystals were full of tiny imperfections inside the crystal which also made them unstable.
• By shining a violet-blue 500 mW laser for 5 minutes on those parts of the crystal when making the film and during ageing, they were able to fix these imperfections and force the ions to form the perovskite structure.

• The result was that the cells retained almost 100% of their original performance in terms of efficiency after 2000 hours or 3 months under simulated daylight conditions.
• At such low degradation rates, these cells could potentially last 5 to 10 years before degrading to less than 80% of their original performance.

• And what if we now combine that with removing surface concavities from the start?
• Could we triple those 5 to ten years and finally make perovskite cells that can last as long as a silicon cell?
• I think it’s possible!
• And so does a company called Oxford PV

The world’s first commercial perovskite solar panel

• I get excited when I find breakthroughs like these that make technology advance in huge leaps.
• But these reports are only in the lab.
• Scaling from lab to industrial production is the bane of any engineer or scientist!
• I know you feel me on this.
• How many times do researchers yell “this will change everything” only to not change anything?
• But what if I told you that perovskites are about to finally make the jump from the lab to our homes?
• Yes. That’s what UK-based Oxford PV promised for this year.

• The spinoff company from Oxford University partnered with Fraunhofer Institute for Solar Energy Systems ISE to make the world’s first commercially available perovskite/silicon tandem solar panel.
• I’ll explain what that is in a minute.
• At 25% efficiency, it’ll be the most efficient commercially available solar panel in the world.
• The panel will be 1.68 m² in size and produce 421 watts.
• Oxford PV also makes perovskite-silicon solar cells in M6 format with an efficiency of 26.8%, but only in low volumes, but the potential is there for utility-scale panels by 2025–2026.
• They’re not telling how long these panels will last, but if they’re going commercial, you can bet they won’t last just a couple of months or years.
• They have to be competitive with current panels, otherwise it would be business suicide for both companies.
• Other companies are also working on this technology:
  • QCells is developing a 26% efficient commercial-sized module that can last 30 years.
  • Saule Technologies from Poland/Japan prints perovskites on large sheets of flexible plastic.
  • But none of them are at a commercial scale yet.

Why is Oxford PV important?

• I’m telling you, guys, if Oxford PV solved perovskites durability problem, this is big!
• This could be the biggest leap forward in solar energy of the decade because tandem cells have the potential to more than double current panel efficiencies.
• In theory, they could go all the way up to 43%, with the current world record holder already certified at 33.9%.

• If you’re thinking, how did they manage to break the Shockley–Queisser limit of 30% efficiency?
• They did it by sandwiching two cells together.
• A neat feature of perovskites is that they’re great at absorbing visible light.
• But they’re transparent to infrared light, which silicon cells are great at absorbing.
• So, you can sandwich the two together and get a perovskite/silicon tandem cell that absorbs much more light!

(Perovskite + silicon absorption spectrum)

• Some of the other many benefits of perovskites is that:
  • They require very cheap and abundant raw materials.
  • These are easily processed. You can make them almost at room temperature by mixing solutions on a substrate surface.
  • Silicon cells require high-purity silicon that is processed at over 1000°C.
  • Since they’re great at absorbing light, you can make the super thin!
  • You can make a high-performance perovskite cell just 0.015 microns thick.
  • That’s 1,000 times thinner than a human hair, which, by the way, is about how thin silicon cells are.
  • So, you can make perovskite cells using less than one one-thousands of the material mass compared to silicon.

Cons of perovskites

There’s no doubt about it. These solar cells are awesome

But they’re not perfect.

• Remember I mentioned they’re made with lead compounds.
• Lead is toxic and a strong pollutant.

• There are non-leaded variants, but they’re nowhere near as good as the lead halide-based cells.
• So, recycling and disposal will be a big issue for these panels, especially if they don’t last as long as silicon panels.
• Besides the longevity or degradation problem, this is new tech, so there are still many hurdles to overcome regarding scaling production.
• Another big issue is certification. These cells perform differently from silicon cells and haven’t been studied for as long.
• So, there’s a lot we don’t know about how they’ll perform in 20 or 30 years (they haven’t even been around that long) making it very hard to develop industry certifications around them.
• And then there’s always the issue of market acceptance.

I want to ask you a question:

If someone walked up to you and said: Listen: Here’s a solar PV system for your home that costs half the price but lasts 15 years instead of 25, would you take it?

One way to compare systems with different lifetimes is through the system’s levelized cost of electricity or L.C.O.E.

So, I wanted to answer this question for myself and compare my current system’s L.C.O.E. with a few different hypothetical systems with perovskite cells.

• I used an online LCOE calculator to make it easier. I’ll leave a link to it in the description. (https://lcoecalculator.com/)
• The L.C.O.E. is the total cost of generating electricity divided by the total energy generation during a system’s lifetime.

• This is what my generation looks like so far this year for my 12kW system with 30 panels.

• So far they’ve generated 11,900 kWh of electricity and will likely generate about 18,500 kWh by the end of the year, averaging about 615 kWh/year each.

We’ll make some assumptions here:

• The installation, maintenance, and all other hardware costs apart from the panels will be the same for both systems.
• I want both systems to generate the same amount of energy per year.
• The difference will be the system’s life span, the efficiencies, the number of panels, and the cost of the panels themselves.
• I’ll assume ⅓ the cost for the perovskite panels, which is reasonable, considering the much lower amount of raw materials and their cost and the easier manufacturing process.
• And I’ll assume a 50% higher price for the tandem cells since they’ll include the cost of both cells plus a bit more for the extra process of sandwiching them together.
  • My panels cost around $150 each, so I’ll assume $50 for the perovskite panel
  • And I’ll assume $225 per perovskite/silicon tandem panel.
• I also estimated the performance degradation rate so that all systems will have the same final performance at the end of life.
• These are the results:

Vs. Vs. vs.

So, you can see that switching to a 25% perovskite panel that lasts half as long as regular panels brings the upfront capital cost down to $21,600.

• That’s $8,400 less than what I paid.
• That’s a big difference.

• But the LCOE is higher, so it doesn’t make any sense.
• With tandem panels like the ones Oxford PV is about to roll out, things are even worse if the panels last only 12.5 years.
• The cost would be 17 cents per kWh vs my current 12 cents. That’s over 40% more expensive.
• The only way for Oxford PV’s panels to compete is if they last at least 20 years.
• This tells me they must have cracked the durability problem, otherwise, it just doesn’t make sense.
• This gets me really excited guys, because tandem cell efficiencies already reached 33.9% and could go to over 40% making solar even cheaper even if the panels cost twice as much!
• What do you guys think?
• Let me know your thoughts in the comments below!
• Thanks for watching!