The Tucson Electric Power test yard is the size of a small used car lot. Just steps from East Irvington Road, adjacent to a massive TEP generating plant, the yard holds not a cross-section of decade-old vehicles, but an array of photovoltaic modules of every hue.
Daniel Cormode, Jason Veatch and Stephen Pulver, all graduate students in physics, have come to make rounds as part of a University of Arizona project to collect data from the 22 strings of several hundred panels.
"Not all of them are hooked up," said Veatch, "not all of them are working." Their attention is drawn to a shelter that looks like a bus stop. There, lines from the panels run to a data acquisition system, or DAS box, that takes vital signs. Computer cards in the DAS box collect data and dump it to a computer via Ethernet.
"In here, we're measuring the direct current voltage and current," Veatch said. "From here it goes up to the inverter, which turns direct current into alternating current."
A tiny weather station monitors temperature, wind speed, radiance and wind direction – all crucial factors in the functioning of the panels. Heat hurts their efficiency; wind cools them off.
The panels are on the grid are not large in number compared to the nearby generating plant, according to Veatch. Still, they generate about 90 kilowatts of power, about enough for 45 houses.
"Compare this guy and this guy," said Cormode, gesturing at a single row of bluish panels and a double row of black panels. "He," the blue panel, "is much more sensitive to heat than he" – the black panel – "is."
"People talk a lot about efficiency in solar panels," he continued, "but what they really want to talk about is dollars per watt. The fact that this row here generates as much as these two rows put together is only an issue if your roof is this big. But if you've got space for two of these, the two systems cost the same."
The blue ones "we've found are less sensitive to heat; they're also less sensitive to shadows," Cormode continued. "So if I stand right here, like this," – he casts a shadow across the panel – "I have essentially shut this solar panel off, so it's barely doing anything now. It's gone to about 10 percent of its original production just by shadowing it this much." The lesson: if you're covering acres and acres, these are more efficient if you lay them flat.
The monitoring program, directed by Alexander Cronin, UA associate professor of physics and optical sciences, is a partnership with TEP arranged by the UA's Arizona Research Institute for Solar Energy, or AzRISE.
TEP was going to shut down the test yard because they didn't have staff to run it, said Joseph H. Simmons, co-director of AzRISE and head of the department of materials science and engineering. AzRISE told the utility they would look for a way to keep the yard running in partnership with the UA.
Cronin was interested in the work and had students to put there. William Conant, UA assistant professor of atmospheric sciences, signed on to do predictive modeling of how photovoltaic panels might perform under a variety of conditions – temperature, wind velocity, cloud cover.
"So we're finding things that are really interesting that you can only find out in the field," Simmons said.
The partnership is emblematic of the sort of bridges AzRISE is trying to build between segments of the University, businesses and utilities.
"We try to form teams of faculty and industry and utilities to work toward solving some of the key problems to widespread adoption of solar energy in the state of Arizona and eventually in the nation," Simmons said. "We want to facilitate, we want to organize and we want to lead the development of solar energy in Arizona."
When AzRISE got into business, with a grant approved by the Arizona Board of Regents through the Technology and Research Innovation Fund, "there were probably three or four faculty members doing solar research and that's it." Today, more than 20 programs, 100 students and about 50 faculty are involved. "The way we did that was that we had the vision that we would spend a very small amount of funding to support the operation of AzRISE and take the rest of the money that we got from the Board of Regents, which was coming from the TRIF initiative, and use that money to support seed projects," Simmons said.
TRIF is a special investment in higher education made possible by the passage of Proposition 301 in November 2000.
"The basic idea was to try to turn around the attitude," he said, so that "solar energy was something exciting to get into."
The institute's other co-director, Ardeth Barnhart, brings a background in policy planning and economic analysis. "Our role is not just as a broker," said Simmons, "but we actually plan."
One of their priorities for a year and a half has been studying compressed air storage of solar energy generated during the day. Simmons said they've been out in front of Washington on the issue. "The last six months, the Department of Energy has gone haywire about the need for storage," he said.
"We formed a consortium in Arizona called AzREST – Renewable Energy Storage Technology," Barnhart said. "It includes every single utility in the state of Arizona and our charter is to move some of the research and development forward in renewable energy and storage and get them to come together in some kind of large deployment of this so that we'll have something in the ground that they can contribute to as a group. This is something that, as far as we know, no other state is doing."
Ben Sternberg, UA professor of mining and geological engineering, has developed an underground imaging system that can identify areas where compressed air can be stored, then used to power turbines when solar-generated electricity is unavailable.
"This is critical to the utilities," Simmons said. "They are never going to change to renewable energy until it can be proven that it's safe and it's reliable. All of their savings could go out the window if they have to turn on their natural gas burners to make up for every time a cloud goes by."
Aside from the large, high-profile projects, Simmons said, "a lot of our wealth right now is in our ability to do economics on this and policy development." The ability to integrate the science with the economics is unique.
"If you go to TEP today and say, 'Why aren't you doing solar energy?'" said Simmons, "they would say, 'We need to estimate the technology, we need to evaluate how much this is going to cost so that we can set our rates properly so that we don't wind up bankrupt.' Ardeth and I have been working to put teams together to do pilot plans so they can see the technologies working side by side. They can see what the performance is, so they could put it into their model." At the same time, they could do the economic study so they could have a reliable evaluation of what costs are going to be.
In Tucson, a pilot program at Tucson International Airport will combine TEP, Raytheon and SOLON Corp., a manufacturer of solar modules and photovoltaic systems. Other demonstration projects will take place in Flagstaff and Phoenix. Each will give AzRISE a place to test large-scale storage and concentrated solar and to take measurements.
Bill Richardson, director of research and development for SOLON, who also is a UA alumnus, sees a distinct advantage in having the University and its research might in the region.
"From my perspective and my job, it's a huge asset to have the University here in Tucson," he said. "There are so many people working on so many different things, and if I can keep my ear to the wall and be involved at the University, that benefits us as a company."
When it comes to hiring, "That's usually where I look first," he said. "I'll look for someone here in Tucson."