The following is an excerpt of an interview with Vladimir Bulovic, published in the Spring 2019 issue of Energy Futures, the magazine of the MIT Energy Initiative. For the full interview please use the link above.
Vladimir Bulović, the Fariborz Maseeh (1990) Chair in Emerging Technology, and the members of his ONE Lab have been creating next-generation, lightweight, flexible photovoltaics that could change the way the world deploys solar energy systems. He’s also the founding faculty director of MIT.nano, shepherding the evolution of MIT’s new nanoscale research facility that will support thousands of researchers from academia, startups, and industry. He recently spoke with the MIT Energy Initiative (MITEI) for a podcast episode on game-changing technologies. Below is an edited version of his conversation with Francis O’Sullivan, former director of research at MITEI and a senior lecturer at the MIT Sloan School of Management.
Q: We’ve seen dramatic reductions in the cost of panels, and we’re seeing real deployment today. There’s a tremendous amount of excitement about solar energy offering a pathway to very significant decarbonization of electricity systems. With that said, some people, including yourself, have begun to reflect on some of the inherent limitations of today’s crystalline silicon technologies. Tell us about the journey that solar has made over the past few decades—and how we can build on the momentum of the low-carbon energy transition.
A: I would start by emphasizing that the solar technology of yesterday is nothing like the solar technology of today. And the solar technology of tomorrow will be even more different.
Today’s solar panels are dramatically improved, both in lifetime and efficiency, and can be made more economically due to standardized and scaled manufacturing. Today, two-thirds of the cost of installed solar is spent on installation and only one-third on the module itself. This implies that if we can make the installation simpler, we might be able to reduce the cost of solar technology by a factor of as much as three. What does that imply for the cost of solar electricity, which today can be bought for as low as 5 cents a kilowatt-hour? Reduce it by a factor of three, and you are at less than 2 cents a kilowatt-hour. That’s remarkable. No other electricity-generating technology can reach such a low cost.
As the cost of the solar cells comes down—and as we make them easier to install—it will become obvious that a thirty-year lifetime is not a necessary requirement for installed solar modules. A ten-year lifetime will be sufficient. Costs will be low, and installation could be as simple as stapling rolls of future thin-sheet, lightweight solar modules to the roof. With lightweight solar modules you would not need to reinforce your roof, and delivery of such modules to remote parts of the world that are longing for electrical power will be much easier to do than with the present silicon. The developing world market might be the perfect stepping stone for the broader introduction of this new type of solar into the developed world. The weight of a solar module would become a very significant metric for the deployment of such technology.
I would also say that there are novel modalities that will start coming through in the use of solar. Solar as a power source is brilliant. Sunlight gives us 10,000 times more energy than we consume in the course of a year, but the challenge is collecting it all. If you can collect all the sunlight for one hour, we can power the planet for one year. The catch is that for that one hour, half of the entire planet Earth (the half facing the Sun) needs to be covered with solar cells. The challenge of such large-area deployment is quite significant.
If we can generate solar activity from the surfaces of objects we already build and touch, that might be another way of deploying solar energy. But since by design solar is meant to absorb most of the incident light, a typical solar cell is very dark-looking, or it reflects blue due to the anti-reflective coating that’s on top of it. So another technology that you could consider is the so-called invisible solar cells—solar cells that do not absorb any visible light, and hence appear transparent (invisible), but do absorb infrared and ultraviolet light. These transparent solar cells are never going to work as efficiently as silicon or some of the other dark-looking cells, because we’re purposefully throwing out a third of the available spectrum (the visible spectrum). Nevertheless, the Shockley-Queisser efficiency limit on these cells is on the order of 21 percent for a single junction versus 31 percent for silicon. Yet, when you make them, they look like absolutely nothing. They look like a piece of glass.
Q: You recently participated in an event in Washington, DC, reflecting on some potential game-changing technologies in the energy space, along with some of our colleagues from Stanford, to help policymakers appreciate the need to support the underlying research. Where are we today—nationally and internationally—in this arc of innovation and seizing the opportunities that we see from the work in the lab?
A: The new type of solar is coming. In the next five years, we’ll have access to more readily deployable, lighter, very inexpensive solar energy, generating electricity at less than 2 cents per kilowatt-hour. If we are not the ones, as the United States, to lead the solar cell technology discovery and scale-up, some of our economic competitors might embrace that challenge. If and when they mature the new solar technology, we risk being in a dramatically reduced position. Our energy would be more expensive than the energy utilized elsewhere for the production of food and for the support of everyday needs. As a result, we would be disadvantaged, just because we haven’t opened our eyes to the opportunity today: that we should seize the moment and be the lead—as we are presently—in developing the next and the next set of ideas needed to give us this very inexpensive form of electricity.