IRA FLATOW: This is Science Friday. I’m Ira Flatow. If you follow me on Twitter, you may have noticed me joyfully posting about my electric bill, $9.62. Why so happy? Well, because last year the bill was over 300 bucks. Want to know my secret? I’m happy to share it with you.

This year, I installed solar panels and a battery. For me, the decision was part economic, part emotional. I had the space. I had the cash. And as listeners of this show probably know, I’m really interested in renewable energy. So it made sense to turn my home into its own power generator, which produces enough storable excess electricity that I’m actually feeding power back to the grid at times during the day, even in peak air conditioning season.

That is how the state treats my home, as an electric utility. My power company siphons off power from my panels and my battery during peak demand time to power someone else’s home. And it pays me back, I hope, at the end of the year.

But don’t get me wrong. This is not a get rich scheme. I probably won’t even break even for what, six to eight years. But that’s not why I’m doing it. I’m doing it because it feels like it’s the right thing to do. Obviously, I’m not the only one who’s been thinking this way. Do a quick search about solar power and read the headlines– solar energy is booming all across the country, solar is disrupting the fossil fuel industry.

So joining me today to talk about where we are with solar energy, how it fits into the national grid, what new solar technologies are in development, are my guests– Dr. Joseph Berry, senior research fellow at the National Renewable Energy Laboratory, in Golden, Colorado, Sam Evans-Brown, executive director of Clean Energy New Hampshire, in Concord, New Hampshire. Welcome, both of you, to Science Friday.

SAM EVANS-BROWN: Thanks so much for having us.

JOSEPH BERRY: Pleasure to be here.

IRA FLATOW: Well, it’s nice to have both of you. And I want to start by reading a few headlines– solar power booms in Georgia, world’s largest solar power energy storage nears completion, solar costs dropped more than 70% over the last decade. It seems to me there’s great news about solar every week. Is it the best time for solar so far, Sam?

SAM EVANS-BROWN: You know, it’s funny that you ask that. And the landscape really varies from state to state. And I would actually argue, where I live you may have slightly missed the best possible time, because there was a bit of a window a couple of years back, when the solar market was really starting to respond, costs were declining really strongly, but the incentives hadn’t had their wings clipped quite yet.

When we installed our panels in 2015, there was still a state rebate that one could take advantage of, which has now gone away. And so we were able to take advantage of cheap equipment but also a favorable incentive landscape. And you mentioned that you’re going to wait six to 10 years for your panels to pay back. Ours paid back in about three.

That’s the benefit of being someone who– at the time I was a reporter covering the renewable energy industry, and I sort of knew what the trends were and was able to jump right at the right moment. So it’s one of those things. It’s like planting a tree. When’s the best time to plant a tree? The best time is 20 years ago. The next best time is today.

IRA FLATOW: Well, I did get a federal tax credit that I’m waiting for at the end of the year. I don’t think it has been extended, or it’s supposed to slowly peter out, but I’m getting, I think, like 20%, 22% back.

SAM EVANS-BROWN: Yeah, the federal tax credits have stepped down. And they are set to continue slowly stepping down. But they do tend to get extended frequently at the last minute, frequently as part of another bill, as part of a deal struck in Congress.

So I know a lot of folks in the solar industry, who are the folks that we represent, are anxious and hoping that that will happen again, because even though solar is cheaper than it’s ever been, it still helps to have that federal tax credit if you’re trying to– if you’re standing on a customer’s doorstep and trying to sell a system.

IRA FLATOW: Joe, you work on the tech side of solar research. Does seeing headlines like these and seeing more solar deployed change how you feel about the work you’re doing?

JOSEPH BERRY: I mean, it’s always exciting to see solar deployed. But of course, the goal is to make it even more pervasive than it is. At the moment, we’re really talking about residential. What we’d really like to do is address the utility scale side, where power producers are also installing solar, in order to meet their demands from their customers. And that really changes the equation of how we think about what we want to technically achieve on the research side, if you will.

IRA FLATOW: Mm-hmm. So we are still looking for that major ramp-up in production by companies, usage by energy companies.

JOSEPH BERRY: That’s right, because while it’s relatively inexpensive, it’s not as inexpensive as it could be. And as you pointed out in the intro, Ira, you had the bucks to do it. Not everybody does have the bucks to do it. But it’s really important if we’re going to make a dent in things like the total amount of emitted carbon, that we make solar much more pervasive than it is now.

And there are challenges with grid integration and other kind of aspects of the technology that have to be worked on, but from a performance perspective, I think, based upon the work we’re doing at the lab, we’re kind of just getting started. In other words, in another five years the same solar panels that you have on your roof, in terms of area, could be producing easily 30% more electricity per unit area.

IRA FLATOW: Well, talk about that. How can you bring up the efficiency of solar panels?

JOSEPH BERRY: Well, if you look at the goals that have been outlined these days by the US Department of Energy, the goal is to make the cost significantly lower. And one of the strategies that we use to do that is to make what we call tandem devices.

So most PV that you get as a residential or commercial user, anybody who’s on the planet, basically, is single junction, mainly silicon, although Alcatel is a really large player in the US market.

IRA FLATOW: Just so our listeners know, PV means photovoltaic, the system that turns sunlight into electricity in a solar panel.

JOSEPH BERRY: But once you go off-planet, i.e. places like Mars, the Mars Rover, we use what you call multi-junctions or tandem technology. And that basically cuts the solar spectrum up into different colors, if you will, and that allows us to convert the energy much more efficiently than we could if we just had to use a single junction device. So by making multi-junctions, we can really push the efficiency higher. The question is, can we do that economically enough to bring in the stuff that we use on satellites back down to Earth, so to speak.

IRA FLATOW: So we know how to do it. It’s being used on Mars and in satellites. We just have to, what’s the word, scale it up?

JOSEPH BERRY: We have to scale it, and we have to make it much more manufacturable. That is to say, we need to be able to do it at scale and at low cost, so that’s the catch. And if you look at a lot of the technologies that we currently deploy in space, they’re very expensive at a basic materials level.

We often talk, in our group at NREL, about embodied energy, the amount of energy you have to put into something in order to make it to begin with, because that’s something that you have that you have to pay back, once that solar cell is, say, generating electricity.

And for typical silicon-based panels that you have on say, your roof, the energy payback time is somewhere between two and 1/2, three years to basically generate the electricity you needed to basically put those together. We’re looking at materials that are an order of magnitude lower in embodied energy than that. In other words, the energy payback time is something on the order of two or three weeks.

IRA FLATOW: Two or three weeks?

JOSEPH BERRY: Yeah, those are the kind of numbers we want to hit.

IRA FLATOW: All right, let’s talk about some of the basics of solar power. And we’ll talk more about the efficiency of solar panels later, because it really is interesting. Sam, let’s talk about some statistics. Do we know how much the use of solar energy has gone up in recent years, and do we know how much of that growth is from corporations or just from users like I am?

SAM EVANS-BROWN: Well, what I can tell you is that we’re at about a place where we’re installing somewhere on the order of 18 gigawatts DC every year. And to put that in context, that means that when those solar panels at noon on the sunniest day of the year, when they are cranking out their maximum capacity, could power a large chunk of New England. And that amount is being added around each year, here in the United States.

And so it’s nothing to sniff at, but you have to remember, that’s just when they’re going at that peak moment. So it’s a technology that’s being deployed rapidly in the sunniest parts of the world. It is genuinely the cheapest kind of electricity generation you can build at the moment. And it’s reached the point where it’s starting to substantially drive out other types of generation, out of the market.

So if you look at the types of generation that are being proposed in the United States right now, in 2019, 32% of new generation that was coming online was natural gas. In 2020, that had dropped to 18%. And then so far in 2021, we’re at 0% natural gas that’s been added to the grid this year, whereas solar continues to rise. It’s now up to 58% of new capacity, that’s been brought online.

So the market is speaking. The market is saying that this is the stuff that’s cheap enough to bring to market. But there are a lot of challenges to come. We’re at such low levels of penetration that solar is still able to simply operate by taking up load that needs consuming. And we haven’t hit a point where there’s so much solar on the grid in most places, where the grid is really having to dynamically respond and figure out what to do when that solar starts to go away, as the sun goes down at the end of the day.

IRA FLATOW: Well, let me get to that point then. I mean, what if everybody says, hey, I want to do what Ira did and put solar panels on my roof. And is there enough supply to meet demand? Are there enough solar panels that people could buy?

SAM EVANS-BROWN: Well, so actually, I think, long before we get to the point where there aren’t enough solar panels to buy, we’ll hit a point where companies start to struggle to make money installing the solar panels. And in particular, I think, on the utility scale side that’s going to become pretty acute, because a utility scale solar array sells into the market. And the markets for electricity– designs vary across the country, but many of them are setting a market price– every five minutes the market price changes.

And when there’s a lot of solar in the middle of the day, those prices crater. And there are parts of the country where, because of various subsidies and other mechanisms that the power producers have to continue to make money, even when prices hit zero, the electricity prices can often go negative, in the parts of the day when the most variable renewable technology is online.

And so that is going to threaten the business model of all of these solar providers. And that’s when we’re going to have to start talking about market innovation that will encourage bringing other types of resources to balance that online.

IRA FLATOW: Yeah, because we have seen stories– I have seen stories, especially coming out of California, where they make so much solar energy now they don’t know what to do with it sometime, during the day. There were stories about having to pay Arizona to take it off their hands.

SAM EVANS-BROWN: No. And that’s exactly right. I think California is really the one that points the way to the challenges that the rest of the country is going to have to face. And similarly, California is probably the state that’s going to start to figure out many of the solutions first, because they are so big, they have so much capacity to study these problems, and they have the ability to bring solutions to bear.

In fact, the California ISO, the Independent System Operator, which is kind of like the air traffic controller for the grid, is actively working on reforming their markets to try to figure out how it is that many of the balancing resources could be brought online.

JOSEPH BERRY: I do think that, at the end of the day, you really do have to think both about the technologies and what the marketplace looks like for how you implement those technologies, to offer an opportunity for people to win economically, so to speak. So there’s a balancing act between all these things. We value electricity differently depending upon how we’re using it.

We value the battery in our phones differently than we value the electricity that comes out of the wall because of the grid. And so the grid is kind of an interesting challenge to some of the market penetration of new renewables.

And then the other aspect of it is, again, if we want these kind of impacts to be equally beneficial to everybody in the US, we have to find really effective market ways to really take advantage of the lower costs that these technologies really can provide.

IRA FLATOW: This is Science Friday from WNYC Studios. In case you just joined us, we’re talking about solar energy and the future of electrification with my guests, Dr. Joseph Berry, senior research fellow at the National Renewable Energy Laboratory, in Golden, Colorado, Sam Evans-Brown, executive director of Clean Energy New Hampshire, in Concord, New Hampshire.

And will we be faced again and have a solution this time around for communities that can’t afford high costs of electricity and it be available for under-served communities, at this time, as we think about distribution of electricity?

JOSEPH BERRY: Well, I think there’s an opportunity to. I mean, these are challenges that– I’m a material scientist/device physicist person. And so I’ll have to defer to some of my more clever colleagues, who really do look at some of the economics of these things.

But certainly, if you talk to people who are working on these technologies day in and day out, we don’t really feel like we’ll have succeeded if we leave people out. It doesn’t do us any good to have regions where we’ve got nice, clean parks and electrified cars if there are other places where, say for example, we were generating all of that electricity with coal. Now clearly, given solar’s prices, we have an opportunity to get rid of that.

But we do need to think about the implications of putting utility scale power plants in different places and what happens when those power plants reach the end of their lives. That’s, again, something that we’re working pretty actively on, to try to develop what we call circular economic concepts when we’re designing these systems, from the beginning. So this is an active area of research for us at NREL.

SAM EVANS-BROWN: Well and Ira, I think your question really gets to the right way to be thinking about this, which is that we shouldn’t just be looking at what is the cost of solar and what is the cost of natural gas, and comparing those two things and trying to decide which is the right resource to go with. What we should be looking at is total system cost.

And increasingly, as variable renewables are starting to drop in cost and as some of the technologies that we discussed– the information and communication technologies that would allow the grid to talk to our homes and use our homes as sort of distributed batteries, in all the various ways that they could do that– as those costs have started to drop, it’s started to become clear that there might be a system that is radically different than the grid that we use today, that is still cheaper than the grid we use today.

And I would point to an analysis by a gentleman named Chris Clack, who works for a firm called Vibrant Clean Energy, who built a very granular computer model of the electricity grid that integrated the weather and made all sorts of assumptions about what technology costs would be down the line. And he estimated that having a high degree of distributed renewable generation out in the community on the edge of the grid, as they say– if we think of the grid as a wheel with a hub in the center that’s a power plant and spokes that go out, grid edge refers to our homes– and Chris Clack’s model spat out a solution that said that having a lot of grid edge technology would be the most cost-effective solution, saving something on the order of a half a trillion dollars.

And so I think that as technology changes, the assumptions of what is going to be the most cost-effective grid is also going to change. And we really need to be thinking hard about what that means for policy making every step of the way.

IRA FLATOW: So would the grid be more localized? Which is the better way to make it– so that everybody has their own source of power, like their solar panels on their roof, or to make it more centralized? Sam, what do you think– what’s your opinion about that?

SAM EVANS-BROWN: I think that the answer to that is, yes, and. My read of the studies that have been coming out is essentially that putting more renewables at the edge of the grid and making it so that your local circuit, the local feeder that the big transmission line connects to from some far away power plant, making it so that that local circuit is optimized on its own and is, much of the time, generating the electricity that it needs. What that does is, it frees up that big transmission line to do other things.

IRA FLATOW: We have to take a break. And when we come back, continuing our dive into solar energy and how it’s disrupting the fossil fuel giants. Stay with us.

This is Science Friday. I’m Ira Flatow. In case you’re just joining us, we’re continuing our conversation about solar energy, its potential, and its limitations, and its future, with my guests, Dr. Joseph Berry, senior research fellow at the National Renewable Energy Laboratory, in Golden, Colorado, Sam Evans-Brown, executive director of Clean Energy New Hampshire, that’s in Concord, New Hampshire.

I live in New England. I see that you live in New England. We may be hooked up to the same grid, because I know, of when we had the hurricane that came through, and we were on a storm alert in my home, and I noticed that the grid was drawing off some of my battery at times and drawing some of my solar panels at times. I imagine it was to make sure that somebody else on that grid had enough electricity.

SAM EVANS-BROWN: Yeah, well, you must live in Massachusetts, Ira. Is that correct?

IRA FLATOW: I live in Connecticut.

SAM EVANS-BROWN: Ah, OK. So generally speaking, Southern New England is a little bit more progressive with its policies. I do not yet have the ability, even if I were to install a battery in my basement, my utility has not gotten wise to the fact that it could use my home in that way. So it speaks to, really, the patchwork of energy policy that is part of the challenge here.

There is no federal authority, to come in and say exactly how energy should be regulated at the local level. States have a great deal of authority. And so this, sort of necessarily based on our system, has to be done in a patchwork way.

And it’s funny, you mentioned that you were noticing that your battery was getting pulled off to power your neighbors. I was just noticing, as I was sitting here in the interview– I have the ISO New England app set up on my phone– and I just got a notification that power prices are spiking right now, because it’s hot. Air conditioners are running. The grid is slightly stressed. The coal plant that’s down the road from my office here, which is the last one in New England, is starting to spin up.

So this is– I really just bring it up just to stress how interconnected we all are. And I personally think that leaning into that interconnectedness is the way through, that thinking of our homes as an island and trying to be entirely self-reliant 100% of the time, and have an off-grid homestead is really not a good solution. Because think of the hospitals, and the factories, and the schools, and all these other places that cannot generate enough electricity on their own.

If we’re all thinking about cutting the cord and going off to live on our own little solar homesteads, those places are going to have increasingly higher prices for their power, and we’re going to deepen our equity problems in the country. So I personally think we should be leaning into our interconnectedness and thinking of the resources in our basement as something that can help our neighbors when the grid is stressed but also can help drive down prices.

IRA FLATOW: Do you think, also, with people putting batteries in their homes, not only batteries in their basements but batteries in their garages, I mean, as more people get electric cars, could they also not be seen, when they’re plugged into the home, seen as sources to store electricity?

JOSEPH BERRY: Absolutely. And I just have to say, I really completely agree, that this notion of everything being interconnected is a critical component. And as we do massive electrification, like with the vehicles, most people, if they’re at work– I guess, you know, we’ve all been living through the pandemic, so a lot of times work is at home– but typically, when you drive in in the morning and when you drive home in the evening, those are the times when, often, the utility costs are the highest, at the beginning and the end of the day.

And in the middle, when we’ve got sunlight, if those vehicles are all plugged in, we can charge them at low cost. And that will, again, just make an electric vehicle even more appealing. It’s already great that you don’t have to basically stop and go to the gas station all the time, but now, if you’re actually incentivized to have it plugged in and get it charged up when the prices are the lowest, that’s another great way to increase market penetration.

And it also makes it cheaper for everybody to drive. Of course, there is still the barrier to entry at the moment. While electric vehicle prices are really dropping, they’re still pretty expensive. So that’s, again, one of those challenges. But I think as we look forward, that’s something that really is a problem that we can address.

IRA FLATOW: Well, I want to address something you started talking about earlier, Joe, and I want to get back to that, and that is new materials for solar cells. Let’s talk about perovskite research. What makes it so different from what we use now, and why are people so excited about it?

JOSEPH BERRY: Yeah, so the first hybrid metal halide perovskite material, I believe was reported in Science by David Mitzi, in the 19– I think was in 1999. And so these materials were of interest for transistors, like any semiconductors are, and all solar cells are kind of made out of semiconductors. But the difference with these materials is that they do all the things that we want a semiconductor, that we want to use for a photovoltaic device to do. It interacts strongly with light. It allows charges to move around so we can collect them and harvest them.

But one of the things that we often have to do with semiconductors is make sure all the atoms are just in the right place. And these materials don’t seem to require that, at least when we’re trying to make an initial device, if you will. So we can basically make– the most efficient solar cells we can make out of these perovskite materials are solution processed.

So that’s to say, you can literally use things like inkjet printing to deposit them, which means that printing them at scale and making them large area very, very rapidly, is in principle, tractable. That’s obviously something we have to work at. But when you can then think about manufacturing the materials that you’re making panels out of very, very rapidly at very, very high performance, then that’s the way you drive down costs. And that’s why they’re different than most of the other semiconductors we have.

One of the other properties we really like about them relates to this tandem concept I talked about before. And it turns out, one of the fundamental properties we care about for a semiconductor is what we call its electronic gap. And if it’s tunable, then that means we have different ways of slicing up the spectrum to take advantage of the energy that’s in the light that we’re harvesting. And perovskites have the ability to be tuned quite well, in contrast to a lot of the other kind of materials that we use for PV, like silicon.

Silicon is kind of silicon. It’s kind of the way it is. And it doesn’t have a whole lot of tunability to it. In contrast, these materials can really change their color by tuning their properties. So those combination of things make it unique and allow us to use it to not only, say, do the job of a photovoltaic material by itself, but we can also add it to existing technologies, like silicon, to make them more efficient. And that combination is pretty much– it’s kind of the Holy Grail of things you look for, if you’re a semiconductor physicist thinking about photovoltaic devices.

IRA FLATOW: So what you’re basically saying is that silicon works in visible light that we all can see, but there are other frequencies of the light, like infrared, that it doesn’t absorb, but you can now tune, let’s say, perovskite to a certain place where it can absorb that invisible part. And then you add that to the silicon, and you just get a much more efficient solar cell.

JOSEPH BERRY: Yeah, that’s–

IRA FLATOW: Would that be correct?

JOSEPH BERRY: –that’s the general idea. I mean, in the case of silicon, the problem is really that the high energy photons, light blue light, you harvest it, but at the same time you’re generating a lot of heat. In other words, you’re wasting a lot of energy, and thermal energy. That if you had a solar cell that just harvested that blue light, it would be much more efficient.

But you’d forgo all those low-energy photons, that would be, say, red and other colors like that. So silicon does a really good job of making a bit of a compromise between which photons it takes versus which it doesn’t. But if I can have something that I can put on top of a silicon solar cell, that takes that blue light, harvests it very, very efficiently, then I can combine that with the silicon and make it a system that is even more efficient than either of the two would be by themselves. Does that make sense?

IRA FLATOW: Yeah.

SAM EVANS-BROWN: So I just want to jump in real quick, because these new materials are very exciting. They’re the next frontier. And I don’t want to give the impression that I’m not excited about them, but when we talk about solar innovation, I think that there’s sometimes this sort of ignored piece that is largely what’s been driving the cost down so far, which is innovation in manufacturing techniques.

And in particular, there’s an analyst named Jenny Chase– I follow her work quite closely– and she points to something called diamond wire saws, which essentially, when you are making a solar panel right now, you get a big chunk of silicon and you cut off slices of it, those are what you use to put together the modules. And the width of the saw determines how much of that silicon you waste.

And so from 2016 to 2018, basically the entire solar manufacturing industry transitioned to using these wire saws and wasting much less silicon, and that’s what drove down the price. And similarly, there’s now the same standard materials. Just silicon solar panels are now being made in a bifacial arrangement, which is to say that both sides of the panel absorb light and generate electricity.

And so if you put a panel somewhere that there’s a high albedo, which is to say, like out in the desert where you’re on sand, which is pretty reflective, the light that scatters off the sand and hits the back of the panel can generate meaningful amounts of electricity, too. And so all of these new materials are really important.

And I think for 10 years out, 20 years out, in order to continue driving down the price of solar, they’re going to be the thing that we need to continue investing in. But similarly right now, using the same old materials, there are a lot of more humdrum advancements that have kind of flown under the radar but have been incredibly important to getting us to where we are today.

JOSEPH BERRY: Well, so your point is well taken, but I guess I would argue that, the thing with silicon, a lot of these technologies like bifaciality, for example, these are things that are kind of improving things. But for a silicon device, by itself there’s a basic thermodynamic limit that kind of says, OK, you can’t do much better than this, even if I play a lot of clever games, so to speak.

In addition, certainly the reduction of kerf, which is kind of like the dust that you get when you make these saw cuts, while you can reduce that, there are other kind of approaches that I think are– they’re a little bit more radical, but they’re kind of of a piece where you can essentially do kerfilous technologies. In other words, instead of making silicon in a really large, single crystal and then cutting it up, can you basically make that as a more of a thin film-type deposition?

Those are questions that I think can provide some life to the existing materials. But a lot of those materials are pretty mature. We’ve had experience with silicon that’s older than I am, in contrast with these new materials. I started at NREL about 16 years ago, and the prospect materials were not a thing at that point. So in contrast, at the moment, if you combine a prospect solar cell with a silicon solar cell, you can take it to an efficiency that no silicon solar cell will ever get to by itself. And that’s kind of a remarkable thing.

IRA FLATOW: Give me a number.

JOSEPH BERRY: 29% is currently the record at lab scale, but that’s a silicon perovskite tandem, and that is in a place that no silicon solar cell will get to by itself, at least if it’s operating as a conventional photovoltaic device.

IRA FLATOW: That’s huge. This is Science Friday, from WNYC Studios, talking about solar energy and the future of electrification, with my guests, Dr. Joseph Berry and Sam Evans-Brown.

SAM EVANS-BROWN: And Ira, the reason I bring this up and the reason I think Joe responded so quickly is that there’s been a debate in the energy landscape of, to what degree do we need to be investing in innovation, and to what degree should we be investing in deployment of the existing technologies that we have? And I think most people who look at this closely, again, would say both, both/and.

We need to be investing in innovation. And the urgency of the climate problem suggests that we need to be deploying what we have quite quickly, especially given the price drops that we were talking about right at the outset. And I really only brought up the improvements in manufacturing processes that have driven those cost declines because there are some folks who would hear about the types of technologies that are on the horizon and they would say, well, let’s wait. Let’s wait for those, and once we get better technology, let’s roll that out.

But I think what the experience with silicon solar really points to is that much of the cost decline comes after the lab. And so these advances that Joe is engaged in and that national laboratories are driving are incredibly important. And I don’t mean to say that they aren’t the future, but they shouldn’t be– they shouldn’t give us an excuse not to act now.

JOSEPH BERRY: Yeah, I would argue the future is now, as they say. But I mean, I would agree that we need an all of the above approach. But one of the things that we talk about is the embodied energy. And I have a colleague who’s a theorist, and he said, if you were designing a material to do the photovoltaic task, you would never choose silicon.

So why do we use silicon, and why is it 90% of the market? Well, you can argue, silicon is the most well-understood material that we have, certainly as a semiconductor, on the planet. And when you have the perfect hammer, every problem is a nail. And I think one of the things that we get excited about at NREL, certainly in our research group, is that we now have a different tool in the toolbox to address these challenges.

And it really is complementary. That is to say, we can take an existing technology like silicon to a place it couldn’t go otherwise. And we have an opportunity to basically create a technology that’s even lower cost because of the potential opportunities to manufacture these types of materials in completely new and unique ways. We do a demo in the lab where we actually paint on a solar cell in real time. And so these are things that you can’t really do with existing silicon-based technologies, for example.

IRA FLATOW: OK, that’s a good place to wrap it up, a little bit of future looking, about what might be down the road. I want to thank both of you for taking time to be with us today– Dr. Joseph Berry, senior research fellow at the National Renewable Energy Laboratory, in Golden, Colorado, Sam Evans-Brown, executive director of Clean Energy New Hampshire, in Concord, New Hampshire. Thank you both for taking time to be with us today.

SAM EVANS-BROWN: Thank you, Ira.

JOSEPH BERRY: It was a real pleasure.

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