The evolution of solar energy technology is happening at ASU, as researchers look to find affordable, reliable solutions.
Arizona. Where you don’t have to shovel sunshine, as the old tourism ads chortled. At Arizona State University, students and alumni are Sun Devils. The sun is in the university logo. Solar panels cover almost every structure.
It’s natural then that solar panels take the biggest slice of ASU’s energy research pie. Financial estimates for the next decade point to more than $1 trillion invested in renewable energy globally.
Down in southeast Tempe lies the Quantum Energy and Sustainable Solar Technologies (QESST) lab. In the clean rooms, there’s an eerie yellow glow because the techs work with materials sensitive to certain types of light. It’s kept at a specific temperature and humidity, and everyone wears full bunny suits.
It’s the perfect environment to work in if you have allergies. To a layman’s eye, the process looks a lot like screen printing T-shirts, but with silver paste instead of ink. The lab looks at different ways of engineering panels, with different materials.
“We have unique research facilities,” said Christiana Honsberg, a professor in the School of Electrical, Computer and Energy Engineering
and lab director. “Not only is QESST the largest (university) solar research facility in the United States, it is the only place where you can make a full-size, commercial solar cell. Over the past year, solar companies have been sending their researchers to work with our faculty in our facilities. We are literally teaching the industry how to advance solar technologies.”
Photovoltaics is an interesting example of how the traditional research model doesn’t work well. The U.S. university model tends to be one person, one lab. That makes international competition hard. It hinders solving big-world problems. The QESST labs bring many disciplines together: materials, devices, systems and physics.
The house of the rising sun
Right now, solar panels are at a development level akin to the Ford Model T, but Honsberg said you can look at it a couple of different ways. The Model T showed that the technology worked, it could be mass-produced, and it could be affordable. It showed that Ford’s invention had enormous potential.
“Solar today has shown the potential to act as a major energy source, with still enormous room for technological improvement,” Honsberg said.
A key measure of solar cell performance is efficiency. The theoretical limit of efficiency is around 86 percent. Present commercial solar panels are at around 20 percent. There’s a long way to go. (Honsberg co-invented the Very High Efficiency Solar Cell. It topped out at 42.8 percent.)
“The technology that’s used today in commercial solar cells is fairly similar in most cases to the technology that was developed 20 years ago,” she said. “We’re just starting to see the innovation now where we’re seeing higher efficiency, new types of technology.”
The first modern solar cell from 1954 is still around. (And doing well, by all accounts.) Lifetime in the field is usually determined by mechanical failures — something falls on it and it breaks. “Guarantees are on the order of 25 years,” Honsberg said. “If there’s no mechanical breakage, the 25 years is probably pretty conservative.”
The goal right now is to improve that to 30 years and beyond, because that would reduce the net cost of electricity to the consumer.
There are a lot of myths about solar (some of them shared by energy researchers in other areas).
Honsberg practically has a sideline in trying to determine the origin of the saying “Solar pays for itself, just not in your lifetime.”
“That was never actually true,” she said. “If you look at the published papers, that was never a true statement.”
The energy payback time in solar varies with sunlight. If you put it in the dark, it never generates electricity. If it’s sunny out, the energy payback time is less than a year.
It’s also false that more electricity goes into making a cell than it produces. One of the important things QESST does is focus on education and outreach.
“The technology has been developing so rapidly,” Honsberg said. “The price is falling very, very quickly. A lot of attitudes people have formed about solar are out of date. Even if you look at newspaper articles and they’re quoting prices, if it’s more than one or two years, the numbers are extremely out of date.
“Trying to do a lot of public outreach in order to give people an idea of the potential of the technology is very important because it’s going to be such an important technology moving forward. For California, for example, photovoltaics generate nearly 20 percent of the electricity. In the U.S., for multiple corridors, renewable energy — in terms of electricity production — was over 90 percent of the newly installed electricity. So getting people and students interested in the field is extremely important.”
The lab’s major immediate focus is to develop technologies to meet what is called the Terawatt Challenge, the challenge in developing an abundant, sustainable energy source.
Last year, ASU earned six prestigious Department of Energy SunShot Awards, totaling $4.3 million, ranking it first among recipients in the Photovoltaics Research category for 2017. The 2017 awards mark the second year in a row that ASU faculty won more SunShot Awards than any other academic institution in the country.
Techs down in the labs have a saying: “The evolutionary beats the revolutionary.”
The transistor was invented by mapping out a path. In the late 1940s three physicists said, “We’re going to innovate here, here and here.” That’s the master plan at QESST.
“It’s similar to what we need in solar,” Honsberg said. “At the scale of these industries, just having a major step change in technology is extremely disruptive. You need to have a plan for how are you going to impact the short term, what technologies do you need for the long term? So, it’s less that we’re looking 20 years down the road, but part of that plan in order to get to a really revolutionary result 20 years from now is to have a path of innovation with impact in the shorter term.”
Thinking at QESST is done a bit differently in all realms. Their funding mentality follows that pattern. Instead of asking, “What can I get funding for,” the question tends to be “What’s the target and how can we fund it?”
To date, the lab’s most significant accomplishment has been showing that commercial solar cells still have plenty of room for efficiency improvement.
One in 50 new jobs is solar-related, according to QESST. Solar employs twice the people coal mining does. More than half of new jobs in electricity are in solar. The lab works with all 15 Arizona utilities, up with policy makers and down in the weeds with system development and maintenance crews.
“We are at the edge of being able to harness huge amounts of energy. What will society do with that energy source?” Honsberg said. “We have an opportunity to demonstrate that solar is beneficial to society.
“It’s not about having the next paper published in Nature. We need to define our desired outcome differently — include people’s attitudes. The ‘we know better, believe us, this is the right thing to do’ attitude focuses on the cool technology rather than the outcome. We need to do better and ensure that technology is more integrated with society as a whole.”
Linemen and the duck curve
Electricity has been used for homes and industry since 1882, but cities and everything else have gotten much, much bigger. We’re also drowning in electronics.
Thirty years ago, airports did not have banks of charging outlets at every gate. Homes had TVs and toasters, but not Roombas or the latest shiny goods from Silicon Valley. Quite simply, people are using more power than ever before.
And the electric car explosion is looming on the horizon.
“Everybody always takes it for granted it will always be there,” said Vijay Vittal, Ira A. Fulton Chair Professor in the School of Electrical, Computer and Energy Engineering. “Then there is this added responsibility from the electric utility to provide it reliably and economically. That’s a big issue. You cannot have a gold-plated system and pay enormous amounts of money for it.”
Vittal, an expert on electric power, power system dynamics and controls, is the director of the Power Systems Engineering Research Center (PSERC). Headquartered at ASU, the center is a program of industry and university cooperation. There are 11 other universities and 30 member companies, mostly utilities and system operators.
Gary Dirks, the director of ASU’s LightWorks, calls Vittal’s team “arguably the best transmission group in the country — perhaps even in the world.” They deal with the delivery of energy from the generation side until close to the customer — think big overhead power lines. (Other ASU faculty work at the level of power lines you see in neighborhoods.) They work on transmission design, analysis tools, hardware, algorithms and modeling, and cybersecurity.
“There are people in our group who also deal with the customer-side issue where it goes from the transmission system through the distribution system to the customer,” Vittal said.
They also work on system automation, operation and planning. Operating an electrical system is enormously complicated because electricity isn’t stored. It’s generated as and when needed. Generation to load has to be matched on the fly, in real time.
“We deal with all aspects of this, in terms of planning, design and economics,” Vittal said. “Right now the primary concern is the uncertainty associated with renewable resources. That’s been a big focus of our research.”
Power grids are delicate systems. The vast majority of Americans flip a switch and have no expectation of anything happening besides the lights or TV coming on. Thomas Edison brought residential electricity to parts of Manhattan in 1882, and the last parts of the country to be wired were rural areas in the late 1930s. But west Phoenix experienced brownouts as recently as 10 years ago.
They are also subject to physical issues. Look at Puerto Rico. Their entire grid was destroyed by Hurricane Maria in 2017. Hurricane Katrina took out huge chunks of the grid in Louisiana and Mississippi. The transmission grid east of the Rockies is one interconnected system. So is the grid west of the Rockies from British Columbia down to Baja California.
“This is one interconnected system, so you have to operate it as such,” Vittal said. “Just the size, the scale, the complexities involved require very detailed modeling and analysis. Much of it eventually has to be handled in real time.”
How do you operate the grid reliably with unreliable sources like wind and sunshine? There are 13 faculty members working on this problem. Most of PSERC’s research looks at how to integrate renewables into the grid. It’s progressing well, Vittal said.
“There are various parts we deal with,” he said. “First of all, you have to model these devices appropriately. That’s one aspect of it, so you can accurately do analysis. Then there are people who look at how do you predict wind and solar? Because both long-term and short-term is required.”
The National Weather Service can give a fairly good forecast 24 to 36 hours ahead of time. Not much work has been done on five- or 10-minute forecasting.
“That’s one of the areas the group at ASU is working on on another project,” Vittal said. “We are looking both at currently measured outputs with some historical data and coming up with some statistical techniques to kind of model both the distribution and the point forecast for both wind and solar. So that’s very critical because … the operator is required to handle things in a five-minute and ten-minute horizon.”
That would help the duck curve become less duckier
If you plot out residential energy use, it’s flat during the day, like the belly of a duck, when most people are at work. In the evening, the sun goes down, people come home, and the need for energy ramps up steeply. To manage that, you need storage or the ability to maneuver generation very fast.
Gerald Heydt believes there has to be an optimal mix of conventional energy and renewables.
Heydt recently retired as Regents’ Professor of advanced technology. He is an expert in power engineering; at ASU that’s split between electric, some nuclear and some coal.
Heydt is opposed to dropping everything conventional in favor of renewables.
“The cost would go sky-high,” he said. “There’s a negative side. The utilities would be happy to dump everything and switch to solar if it were so wonderful and so cheap, but it’s not. … A lot of the students we have come in bright-eyed and you start to explain the limitations on all this stuff, and then they get less enthusiastic about it.”
The unreliability of sun and wind is a problem. There’s little wind in Arizona. Even if there were, it’s not a power source you want to run a hospital on.
“We’re cautiously approaching solar and wind,” Heydt said. “There are good engineers who know what the balance should be right now. … You have to have some kind of reliable generation ready to go.”
Power engineers have a phrase called “installed capacity.” It’s the full-load output of a plant.
“Solar does not mean we’re going to reduce the installed capacity for, say, coal and natural gas,” Heydt said. “It means you’re going to use less coal and natural gas. That’s for sure. Every watt hour of solar you’re using means you’re not using coal or natural gas. And that’s a good thing. But you still need a generator. There’s going to be a time when the wind isn’t there. And then there’s storage.”
Vittal believes good storage will eventually be solved.
Grid in a box
While Heydt, Vittal and others work on big overhead power lines, Nathan Johnson works at the level of neighborhood power lines.
He specializes in working where there are no power lines at all.
For the past 15 years, he has set up solutions in countries like South Africa, China, Mali, Honduras, Indonesia, Vietnam, India and Thailand. Johnson has put power grids in 12 countries (four since he has been at ASU).
An assistant professor in the Polytechnic School of the Ira A. Fulton Schools of Engineering, Johnson researches and teaches sustainable and resilient energy systems.
He invented the grid in a box. It’s a standardized shipping container holding solar panels and a diesel generator. It can be custom-designed in three weeks.
“It takes 30 minutes to set up and you’re rolling,” Johnson said.
The box has been used primarily for humanitarian disaster-response operations around the world, but it hasn’t yet been used in difficult-to-reach places in the Democratic Republic of Congo or Afghanistan. Bringing a 40-foot container with all its contents via helicopter to remote villages doesn’t make sense. (Johnson’s answer to a situation like that would be to donkey in a smaller solution in parts.)
“We use a lot of pictures and a lot of diagrams in order to make things as simple as possible from an IKEA-style setup,” he said.
Altering operations or maintenance is more complicated, but anyone can get it up and running.
Johnson leads the Laboratory for Energy and Power Solutions. It’s a research and development team of 20 students, four staff and himself translating energy innovations from concept to construction.
“We do basic science or applied research, physical prototyping, and then testing in our 1-acre grid modernization and microgrid test bed outside,” he said.
They work in four primary areas: off-grid solutions, grid modernization, critical infrastructure and resiliency
, and workforce development.
About 1.2 billion people around the world don’t have access to any power at all. Fly over Africa from north to south at night and, south of the Sahara, there are almost no lights besides brush fires.
How do you bring power there?
“So it’s interesting because the types of solutions that we would provide today for off-grid populations is not unlike how off-grid populations were 100 years ago,” Johnson said. “In essence, it’s a smaller version of the electric grid, a single, isolatable circuit that includes generation and loads. Now, more principally in the last 20 years, is that given the declining cost of solar and storage, now we can add solar and storage to offset the time of operation that a diesel generator would run and the cost of that diesel.”
How bad could the cost of diesel be? It’s around $3.50 right now. In a remote location in a developing nation, it could be $10 to $50 a gallon. If you’re in the military, the estimated cost is $400 per gallon at a forward operating base. That means the price for power is going to be $1-$2 per kilowatt hour. That’s throat-choking to anyone in a grid-connected community. Imagine a summer electric bill of $300 suddenly becoming $1,500 per month.
More and more diesel generator sets are becoming hybridized with solar and storage. You use less diesel and maintenance goes down for communities that don’t have the technical know-how or money to do the maintenance. You would have solar-only homes with one panel and one battery; it would charge a cellphone, run a television, a radio and a few things like that, but no more.
“There’s this really good sweet spot of existing solutions in that 30-cent to $1 per kilowatt hour which can provide basic needs, but can also come at a price point where they could stimulate local economic development,” Johnson said.
Stimulating local economic development is part of a solution ASU is helping to provide in Syrian refugee camps in Lebanon. More than 1.5 million people are estimated to live in the camps. The United States Agency for International Development gave an ASU team
almost $2 million to develop an affordable and portable clean water solution.
One of Johnson’s microgrids is currently deployed in Lebanon. It powers water purification for about 550 people. Another system will be deployed in August. The American government plans to eventually expand the solution in 18 camps in Jordan and Lebanon, benefiting more than 36,000 people.
Making the project successful didn’t simply involve firing up the microgrid and walking away, Johnson said.
Of the endless reports on the situation, none mentioned the needs of local Lebanese.
After 30 years of getting people pushed into your country, watching resources dwindle while international entities put billions of dollars into your country (none of which goes to your people), all while being displaced so that the foreign contractors can live in your houses and work in your buildings, “that kind of creates a rub,” Johnson said.
“A lot of those (reports) missed the challenges of the local citizens and the local economy because they’re taking in tens of thousands and hundreds of thousands of people, and they’re displacing the existing, limited natural resources for the existing population,” he said.
“We switched the focus to benefit to all of those that are affected, whether it be displaced peoples being kicked out of their country or running away from things, or the folks that are taking care of the individuals coming in,” he said.
It’s not only a technological solution. It meshes with local culture and water laws, and it stimulates local economic development by being set up with a local entrepreneur who can technically manage the work.
Johnson is about to do a site assessment for a similar project funded by the U.S. Navy in northern Uganda for Sudanese refugees.