In this episode of This Week in Solar, host Aaron Nichols sits down with Scott Wharton, CEO of Tandem PV, to explore the new frontier of renewable energy: perovskite solar technology.
They discuss why traditional silicon panels are reaching their physical limits, how “tandem” structures are shattering efficiency records, and why this new material is a game-changer for everything from utility-scale power plants to NASA spacecraft.
You can connect with Scott on LinkedIn here.
Listen to this episode here, or on:
* YouTube
* Apple Podcasts
* Spotify
Expect to learn:
* Why NASA is betting on perovskites to power spacecraft.
* How perovskite panels reach way higher efficiencies than traditional silicon ones.
* The three hurdles (efficiency, durability, and scalability) that perovskite must clear to survive in today’s solar market.
Quote from the episode:
“Silicon took 60 years to get to where it is today. Perovskites took about a dozen years… It’s a completely new material science that’s revolutionizing the solar industry.”
— Scott Wharton
Transcript:
Aaron Nichols: Scott, I’m really excited to have you on today because I don’t know anything about perovskite solar panels yet other than the fact that NASA’s really interested in them for space travel. So, where do normal solar panels fall short and why are perovskite panels the future of solar energy?
Scott Wharton: Well, normal solar panels today get about 22% efficiency, so basically for every hundred beams of light that hit the panel, they can convert about 22 of them to electricity. With perovskite tandem panels, we’re already over 29% and the theoretical limit is between 45 and 50%. So the current solar panels basically, through the laws of physics, probably can only get to 26%, so they’re already kind of tapping out for what they can get.
If you want to be able to get higher efficiency and power density, almost everyone in the industry agrees that these perovskite tandem—I’ll explain that in a minute—is going to be the future. Now, perovskite itself is a crystal structure, and it was discovered about a couple hundred years ago. It was named after Dr. Perovsky, a Russian dude and scientist. And the fun fact is, if you go underneath the Earth’s crust about 400 miles, more than 90% of it is perovskite.
Aaron Nichols: Really?
Scott Wharton: But we don’t do any mining or minerals or anything. We basically make it synthetically in a lab. So there’s no earth metals and minerals and mining and we create this very thin layer that is less than one micron thick and it only weighs actually two grams. So it’s super thin and light, but it adds all this more power to a solar panel. So it’s basically a completely new material science that’s revolutionizing the solar industry.
Aaron Nichols: That’s amazing. And for anyone listening, welcome back to This Week in Solar. As always, I’m your host Aaron Nichols. Our guest today is Scott Wharton; he’s the CEO of Tandem PV, which I don’t quite understand how Tandem PV works. So, if you’d introduce yourself and the company, that’d be amazing.
Scott Wharton: Yeah, so first, I’ll start with my background. I am a startup junkie. This is my fifth startup. Clearly there’s something wrong with me; I like to continue to do this over and over again. I’ve been very fortunate in my career. The first two companies I did early stage, they were both in the voice-over-IP telecom space, both of them IPO’d on NASDAQ, the second company got sold to Cisco for $2 billion. Then I started the world’s first cloud video conferencing service called VidTel. So I like to say, I had the right idea, but it was three years earlier than Zoom. So I was a little early, ended up selling the company, and then my wife and I loved traveling.
Aaron Nichols: Pre-COVID?
Scott Wharton: Yeah, this was—we started it in 2008 and then we sold it in 2013. So my wife and I love traveling. So what we did is we got rid of our house and our cars and we pulled our boys, then 10 and 13, out of school and we backpacked around the world for a year with a bag a little bit bigger than a carry-on. I hope probably that’s another discussion in your head. But then when I got back my wife said, “Would you mind not doing another startup for a while?” So, I went to this company that almost everyone here knows called Logitech, and I built the world’s biggest video conferencing hardware business. So this headset, the webcam, a lot of the conference room systems that people are using around the world—Zoom, Microsoft, Google—were something me and my team built up basically from scratch to over a billion dollars a year organically.
Before I came to Tandem PV, I was running a $2 billion a year global manufacturing business for Logitech. And so I’ve been here about two and a half years. Came into the company not as a founder, but there were two brilliant founders who both had PhDs from Stanford in Material Science and Applied Physics—you know, “dumb guys.” And then basically came in to help commercialize the company to go from late-stage R&D to commercialization, which is—I’m sure we’ll talk about—that’s where we’re here now. And then the company itself, the reason why it’s called “Tandem” is that we basically make a solar panel sandwich. We put this perovskite layer on top, we take the traditional silicon cells that are commodity in the bottom. And by having the two layers, you’re actually able to capture a lot more light than you can from one of the other.
Aaron Nichols: That’s amazing. And where do these perovskites come from? Because once again, like I said, I don’t know anything about them, other than the fact that NASA’s so interested in them. So where are they? You mentioned that we’re not mining a lot of them? Are they synthetically created?
Scott Wharton: Yeah, exactly right. We make them in a lab. So we make them in a lab here in California. And then you don’t need to mine them, although I guess that they’re all over the planet—Earth is full of them. But we make them synthetically and relatively inexpensively, and then we process them and convert them into solar panels. And as it turns out, perovskites are incredibly good and efficient solar panel materials. They’re essentially semiconductors.
Aaron Nichols: Why is that? Why are they better at conducting or absorbing sunlight or whatever it is they do?
Scott Wharton: There’s a couple of reasons why. One is that they are actually 200 times thinner than a traditional silicon panel, so it’s a lot cheaper to make. It ends up you putting a thin film down glass, so it’s more like making a TV from a manufacturing process point of view. As I said earlier, it doesn’t use any rare earth minerals or metals or mining, so it’s relatively inexpensive to create the materials. And then it only uses about 10% of the energy to make it. We can make it at a lot lower temperature than traditional silicon panels, which—they’re silicon, they’re sand—you have to heat them up to thousands of degrees and then purify them. We don’t need to do that.
So there are physics and cost advantages. And then the last thing is we’re able to stack them because the perovskite captures a different part of the light than the silicon does. There’s this thing called the band gap, which is how much light can you capture, and we’re just able to capture a lot more light collectively than you can with just perovskites or silicon. So the name of the company “Tandem” was actually formed with this idea of creating stackable solar panels technologies as opposed to just using one of the other.
Aaron Nichols: Okay, so integrating perovskite with existing silicon technology so that everything is more efficient.
Scott Wharton: That’s what we’re doing today. In the future, we might engineer out the silicon where it’s perovskite and perovskite, but today, primarily it’s perovskite plus silicon.
Aaron Nichols: Okay, so that was my next question and you went ahead and answered it for me. So you’re already a step ahead of me, but I was interested in why it takes so much less energy to produce. Now you mentioned that you have to heat silicon—or the sand to create silicon—to a very high temperature in order to refine it. But what do you have to do with perovskite to refine it?
Scott Wharton: Yeah, so part of the reason why silicon and the so-called polysilicon technology is primarily in China is that it’s so energy intensive and relatively dirty. So like 98% of polysilicon comes from China today, so they almost completely dominate it. With perovskites, it’s just you heat it up to a much lower temperature to basically turn it into a crystal structure. So we did a study with Columbia University some years back and estimated it’s about 10% of the energy needed. So it’s an order of magnitude cheaper to make from that point of view as well.
Aaron Nichols: So then what are the raw building blocks that you’re using?
Scott Wharton: Well, you know, that’s our “Coca-Cola formulation.” They’re all about it, but it’s nothing exotic. One example of something that we use in our product is iodine—pretty simple molecules and chemicals.
Aaron Nichols: Okay. Yeah, you can just pull it right out of table salt and throw it into the factory.
Scott Wharton: Yeah, in a way, yeah.
Aaron Nichols: Nice. Well, so, I mean, the thing I’m most excited to talk about is why these are better for spacecraft and why NASA is so interested in developing these?
Scott Wharton: Yeah, there’s a couple of reasons for that. One is because they’re so much thinner than silicon, you can make them quite a bit lighter. Now, obviously, you need thinner materials like glass or stuff, but there are companies like Corning and others that make very thin glass for space. That’s number one. Number two, perovskites are particularly resistant to radiation, so they’re good for being out in space for that.
And then the third thing is, since most of the solar technology comes from China, as you can imagine, people listening, there’s national security concerns. Are we going to get all of our future technology from China? So the fact that there are companies like us and a few others that make the stuff in the United States makes it more Western-friendly from a technology point of view. So I’d say it’s those three things, and then the last thing is the higher performance. So the ability to get into the high 20s or the 30%—when you’re up in space, if you can only send a few things up there, you’re willing to pay for the highest performance possible. So I think it’s the combination of those four things that makes people pretty excited about it.
Aaron Nichols: So why haven’t we entirely switched over to it? If it’s cheaper to make, easier to make, doesn’t take as much heat—what’s standing between us and just entirely switching to perovskite as a solar industry?
Scott Wharton: Great question. So the main thing has been the durability of these products. In nature, perovskites will degrade and fall apart pretty quickly. And if you look at traditional solar panels, they’re almost bulletproof in that you get a solar panel today and it goes 30 years and then it gets to less than 1% a year degradation. Think about anything that goes in your backyard anywhere for 30 years in the elements and doesn’t completely fall apart—you can probably think of almost nothing.
So these solar panels over the last 60 years have become really hard and in very high performance. So the market wants something to be in a similar range—maybe not exactly that, but close enough so you can get to a 25-year warranty with less than 20% degradation of performance. And we now have the technology that we can show based on our lab testing, that we can do that. We’re now validating that outside and through some third parties. But if you think about it, Silicon took 60 years to get to where it is today. Perovskite took about a dozen years.
I think we’ve made much faster progress, but the Holy Grail is: you want high efficiency, you want high durability, and then you need to be able to manufacture it—and you really need to do all three of these things at the same time. If you read about perovskites, people will announce some very high performances but usually, it’s on like a little dot in a lab. That’s not repeatable or durable. That’s kind of our secret sauce—being able to do all three at the same time.
Aaron Nichols: And when I see the headlines coming out of NREL that perovskites have been to 45% efficiency, that’s what they’re talking about—is a little dot on that.
Scott Wharton: Yeah, it’s a microscopic dot that was handcrafted, that has no durability. It may fall apart pretty quickly. And then from a process point of view, you can’t take the dot and scale it. So you really need all three of those things to have a commercially viable product. I think where Tandem PV is now is that we’ve cracked the code on being able to demonstrate those three things at the same time.
Aaron Nichols: Well, it sounds like y’all are going to be in a really good position with where the industry is headed because you must qualify for domestic content with your components as well, right?
Scott Wharton: Not only do we qualify for domestic content, but I would say there’s this misunderstanding in the industry about the tax credits. I think the conventional wisdom is that the IRA is repealed and most of the tax credits have gone away. That’s only partially true. On the consumer side, the tax credits for EVs have gone away and the solar credits for your house, but we’re not selling there. We’re selling to utility-scale. For those, the US manufacturing tax credits were fully adopted by the Republican Congress. Actually, it’s the same as a Democrat. So now I would argue it’s a bipartisan commitment to US solar manufacturing. The tax credits for our customers are maintained as long as they do this thing called “safe harboring” where they basically start the project and have another four years of runway—until 2029 or 2030. So the conventional wisdom that you may hear it’s repealed is actually completely wrong and very favorable now for people like us.
Aaron Nichols: Yeah, we’ve gotten very, very comfortable with safe harboring over the last couple of months. We’ve obviously been forced to, like so many other companies in the industry. But that is amazing. So y’all are placing and fulfilling orders right now?
Scott Wharton: No. What we’re doing is we raised a series of venture funding earlier—we announced early in the year $50 million, a combination of equity and debt. That allowed us to scale up to build our first pilot or demonstration factory. That’s where I’m sitting in now, in our Fremont, California factory. And what we’re doing basically is demonstrating that we can take our products that were basically the size of a tablet and showing how we can build them up to the size of a door—essentially a full-size solar panel. The goal of this factory is not to make money but really to show that we can build it at scale to show all the durability requirements and then to show a customer starting to buy them. The next high-volume factory will be at full size at economic value, but that’ll be coming next.
Aaron Nichols: Well, Scott, you are quicker than most people I’ve interviewed. So I think we’ve gone through the questions I’ve written down. I’d like to take a quick conversational detour because I want to expand on something you said earlier which was that you took a year to travel the world with your wife and kids. I like to tell the story when I’m on other people’s shows that I ended up in the solar industry because I met some circus girls on the beach in Ecuador. And they invited me on some door-to-door sales trips and then it’s just been one thing after the other since then. So, traveling and just the vagabond lifestyle is responsible for so many of the incredible things that have happened in my life. I’d just like to hear you talk for a few minutes on what that was like, especially with a spouse and small children.
Scott Wharton: Yeah, before I went to graduate school, I decided I’m going to take four months off. I ended up going a couple of months in Europe, a couple of months in Indonesia and Thailand by myself, and I kind of fell in love with it. But then I would meet all these Australians in Scandinavia and it’s like, “Scott, I’m so sorry that your trip is so short,” because they were going out for years.
So when we sold our company, my wife and I said, “You know what, let’s see if we can just take a year and get rid of everything and just pull our kids out of school and we’ll just vagabond around the world.” Everything was kind of improvised—we’d follow the sun—but we’d get to a place for a couple of days and then we’d just see if we liked it and figured it out. I’d worked for 20 years at startups and basically to not work full-time and take a sabbatical was really good for me, especially as a man where a lot of our identity is tied up to work. It was really funny—my kids would introduce me and they would say, “This is my dad Scott, he’s unemployed and homeless.” Technically true!
Aaron Nichols: 10 and 13? Oh, wow.
Scott Wharton: They definitely had a twinkle in their eye when they would say that. What was the best thing? Really being with my family 24/7, getting to know them better. What was the worst thing? Being with the family 24/7. Sometimes it was tough because you have no support system out there. Every new place you go to, you have to start community over from scratch. You mentioned being with the same people for 24 hours a day for a year—you just had enough of each other. It was great, we learned a lot, but not every day was an adventure.
Aaron Nichols: I’m so happy that you took the time to do that, man. I mean, I’m continually blown away by the quality of people in the solar industry. I’m in a big WhatsApp group for returned Peace Corps volunteers as well, and there’s just so many people who have just done big, interesting things around the world. That’s another thing I wish I would have done, but I got, sadly, I got rejected by the Peace Corps.
Scott Wharton: Yeah, well, I think you’ve gone on to prove that you would have been a great candidate.
Aaron Nichols: Maybe there’s a future Peace Corps for us later. But Scott, to bring it home, I ask everyone who comes on this show the same closing question. Back in the summer, I spoke at my grandma’s 80th birthday party. I realized that 80 years means that she was born into a world where what we call renewable energy didn’t exist. PV wasn’t invented until 1954. Jimmy Carter didn’t put solar panels on the White House till ‘79—and those were solar thermal, not even PV. All of that has happened within her lifetime. So I am curious: what do you think clean energy is going to look like 80 years from now?
Scott Wharton: Well, gosh, 80 years from now, I would say we’re going to look back at the fact that we burned fossil fuels and say, “Why did we do that?” Because I suspect that in 80 years it’ll be 100% renewables. My expectation is that it’ll be solar for the most part, maybe a little wind. I actually don’t think nuclear is going to be that big a deal—I know that’s controversial—because solar is so cheap and getting less expensive all the time.
In 2025, in the world, more than 100% of new power was renewables because people are shutting down coal plants because it’s too expensive, not necessarily for environmental reasons. So I think we are already on the trajectory to solving climate change. It’s not an “if” anymore; it’s a “when.” By 80 years from now, we will have negative carbon emissions and the world will be 100% renewables and we won’t be talking about climate change. We need to accelerate it because we’re getting into some dark times, but I also think this is one of the biggest economic opportunities in time.
Aaron Nichols: It’s pretty amazing, man. Scott, it’s been an absolute pleasure to have you on today. Where do you like to be found if you do want to be found?
Scott Wharton: You can find me on LinkedIn or if somebody wants to drop me a line: [email protected].
Aaron Nichols: Great. Well, for everyone who’s listening this week, thank you very much. That’s been This Week in Solar, and we will see you next week. Thanks so much.
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