AZ Technology and Innovation: ASU Solar Energy Research

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A national project promising a significant advance in technology for converting sunlight into electricity will be led by a team of Arizona State University engineers. With a $3.5 million grant from the U.S. Department of Energy’s SunShot Initiative, the team will develop new ultra-thin silicon solar cells designed to increase the amount of electricity that can be produced through direct conversion of sunlight. Stuart Bowden, the ASU team leader, will discuss the research.

Ted Simons: Tonight's focus on Arizona technology and innovation looks at a national project to advance the ability to convert sunlight into electricity. The project will be led by a team of ASU engineers. Leading that team is Stuart Bowden, who joins us now. Good to have here.

Stuart Bowden: Thank you very much.

Ted Simons: This is a national project, solar cell efficiency, what are we talking about?

Stuart Bowden: Solar cells are a great technology. You have this crystal, and you shine light on it and electricity comes out. It does not get simpler than that. But one of the challenges and one of the sort of our job as a team, that I'm leading, is how can we maximize the amount that we can get out of that crystal? So in the past, the amount of electricity might have been like a curiosity, something you might have seen in children's toys, but now, it's a real industry. So, what is a really interesting statistic, over the last 30 years, the cost of photovoltaic has come down by a factor of 100, so it's sort of this niche market, sort of unreal that we can put it on our roofs. What that means in, say Arizona, in a lot of places, it's cost effective. So put it on the roof, and it will pay back over the life of the system. But it's not true everywhere, so parts of the country, which unfortunately, aren't as sunny as Arizona, and what we're doing, we're going that extra bit, which is taking the cost down by another factor of two. And we're doing that by increasing the efficiency, and to do that, we need a large team of people.

Ted Simons: There increasing the capacity and the efficiency to capture or to store?

Stuart Bowden: It's to capture. So, what we're doing is we're increasing the efficiency of when the sunlight comes in, and how much comes out.

Ted Simons: And how much will be stored because it's a cloudy day for the next week.

Stuart Bowden: Right, always a cloudy day and always a bit of a challenge.

Ted Simons: Does this mean thinner cells? Or what's the plan?

Stuart Bowden: What we did here is, is we sort of went back to the fundamentals of photovoltaics. And we've been making photovoltaics the same way for the last 20 years, and we use a lot of technology, which came from the integrated circuit industry, computer chips. And that's great, if you are making chips because you can make those expensive and still make lots of money; Intel still does pretty well for themselves. But for photovoltaics, the whole cost structure is really different; we need to make things cheap, really cheap. So we said, "Okay, there are some processes that we are seeing in the way we make these that are a bit expensive. How can we go back to the fundamentals?" So we went back to thermodynamics, which sort of governs the way everything works, and we looked at that and said, "Okay, we're going to come up with a new device design, new device physics that will enable us to get higher efficiency, but without increasing the cost." So, it's a, a higher efficiency device, but, it's simpler to make.

Ted Simons: Is it -- is it just a new design without new materials, or are new materials involved?

Stuart Bowden: What we're doing is we're involving some new materials, but the base technology that we are using is crystalline silicon. So the PV panels you see all around the city, most of those, a lot of those are made from crystalline silicon. So we're combining that, really cheap material, a really well-known material, it's really stable, so we are combining that with some newer materials. So, we sort of figure this is important because we get the stability, the known sort potential some of the existing materials, but combine that with new materials that enable us to get much higher performance.

Ted Simons: So you are not reinventing the wheel but making it more efficient, more streamlined.

Stuart Bowden: So the nice thing about this is you don't have to restart everything, go right back to how do you refine silicon and how do come up with the whole industry, there is a big industry for that, which we can leverage. And what is actually nice about this is the way that we're doing these new device physics, we sort of - most semi-conductor activity at the moment, it's fabricated by either a diffusion or a deposition of other materials, and we found that that was limiting the device performance. So with this new device design, we're able to, as I said, when you shine light on a crystal, you get the charges, electrons and holes, and what we want to do is get those electrons out, and we are able to pull the electrons out without any losses. And the jargon is we pull them out.

Ted Simons: Well, yeah, and when you are pulling them out here, are you pulling them -- is the advancement, is it, are we talking big-time exponential increase?

Stuart Bowden: We don't need exponential increase in efficiency. With this project we'll be taking the systems from 20 to 25%, and you think, well, it's not going to make much difference. But, if you look at the economics of it, if you are at 15%, you just can't sell them. So 20% is about where you start making money. 25% you start to make pretty big in-roads. But what's more interesting is that we know, through the similar device designs, that we can get up to 86%. So that will be an enabling technology, so that's kind of the next project.

Ted Simons: And indeed, it sounds like the goal, as you referred to earlier, making solar more economically competitive. And when does it become more economically competitive?

Stuart Bowden: That's a good question. And it depends on who you ask. So, I've been in photovoltaic since I was an undergraduate, so, I've been working in it for a while. And if you work in photovoltaic, you get the question, do you have PV on the roof. It's one of those things, like most homeowners, have a few things to deal with, and plumbing, but it's just last week, I finally signed up for the photovoltaics, so, I figure out the economics were enough and I could justify it enough for the family, it's economics. So, it's a ten-year payback, which I was comfortable with, and maybe a few people are comfortable with, and what we want to do is reduce that down, so that for everyone, it's a no-brainer. It's like installing an air-conditioning system, you think, "Okay."

Ted Simons: And talk quickly about advancing the integration of solar into the grid. Where does that stand now? What can be improved technologically?

Stuart Bowden: Yeah.

Ted Simons: Or otherwise?

Stuart Bowden: It's going to be a challenge. The industry is changing. Any large industry that changes, it's always going to cause some disruptions. The phone industry is probably an example we like to follow. And they went from having a fairly centralized fixed system, and now, you have mobile phones for everyone. When mobile phones first came out, they are viewed with a suspicion, you know, there is these funny things. But now, they are ubiquitous, and we can see this happening with the electricity grid; they are going from a centralized system to more of a cellular system. So the same reason we call the mobile phone system a cellular system, we'll see that with photovoltaic and will be tied into the smart grid concept.

Ted Simons: I feel like we're on the cusp of advances, and enough to get you involved to putting them on the roof.

Stuart Bowden: It's enough to get me to put them on the roof. My mom got there first.

Ted Simons: Good for her, and before you go, MIT Universities in Australia, Switzerland, and how did ASU get involved in this?

Stuart Bowden: ASU is the lead for this project. We started a center at ASU, four years ago, and we built up enough technology, we got a few world records, and we have a pilot line where we have the students to come by, and make solar cells. And we just went out there and attract the other partners, talked to them, said ok, what technologies can you bring to it. So each partner brings the technology. And the University of New South Wales in Australia gets involved, part my background being Australian. By bringing together the technologies, and we find these with photovoltaic, it's a worldwide industry, you need people from everywhere to make a contribution.

Ted Simons: Congratulations. Good luck on the project. And congratulations on the new addition to the house.

Stuart Bowden: Thank you very much.

Stuart Bowden:ASU Solar Energy Research;

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