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Sandia Labs expands, upgrades solar R&D

ALBUQUERQUE, N.M. — Sandia National Laboratories is moving to front and center in industry efforts to harness electricity from the sun.

The lab is investing $16 million to build five regional test centers around the country for solar companies to field-test their hardware before installing multimillion-dollar photovoltaic systems on buildings. It also just completed a $17.8 million upgrade to its National Solar Thermal Test Facility in Albuquerque, and it’s preparing to commercialize new, breakthrough PV cell technology that could cut manufacturing costs, improve efficiency and provide more applications for photovoltaics in everything from clothing to Mars rovers.

“It’s part of the Department of Energy’s ‘SunShot Initiative’ to support manufacturers and expand and accelerate installation of PV systems in the U.S.,” Sandia solar group member Jennifer Granata said of the lab’s new regional test facilities. “The centers are designed to not only provide independent assessments of commercial systems, but to do that in multiple locations and climates.”

All 218 heliostats at the National Solar Thermal Test Facility received new, high-tech glass facets as part of an upgrade. The glass is more reflective, produces hotter beams and more power.

That’s critical for investors to pump money into emerging technology, said Charles Hanley, manager of Photovoltaic and Distributed Systems Integration at Sandia.

“With the trend in the solar industry toward larger systems and greater capital investment … the financial community is increasingly scrutinizing how well these systems operate,” Hanley said. “The regional test centers will provide enhanced monitoring and improved performance prediction capabilities for new technologies being introduced to the market.”

Apart from Albuquerque, centers will be located in Denver; Orlando, Fla.; Burlington, Vt.; and Las Vegas, Nev.

Sandia will install detailed weather stations at testing centers, as well as measuring and monitoring equipment such as simulators, performance curve tracers and infrared and digital cameras, Granata said. Select companies will then set up their own systems of between 10 and 300 kilowatts on site.

“Industry partners will be responsible for the cost of their own systems,” Granata said. “The DOE will provide the test infrastructure, labor and expertise to do all the assessment work.”

Apart from evaluating individual systems, the centers will help develop standard procedures to assess performance of large-scale systems that other labs, utilities and investors can use.

While the regional test centers will focus on PV systems, which directly convert sunlight to electricity, Sandia’s Solar Thermal Test Facility is working to improve concentrating solar power (CSP) systems that use sunlight to heat liquids to generate steam for turbine generators. That facility was established in 1976 in Albuquerque, but much of it had never been updated until now, said Sandia researcher Cheryl Ghanbari.

Upgrades, financed with stimulus money under the American Recovery and Reinvestment Act, included construction of a $10 million Molten Salt Test Loop, and a nearly $4 million overhaul of the facility’s “solar tower.”

CSP systems are increasingly using molten salt to retain heat from the sun because it’s cheap and abundant, and it stores thermal energy for long periods, allowing the systems to generate steam for turbines well after the sun goes down. But energy developers need a better understanding of how pressure, high temperature and flow rates interact and impact a system’s overall operation.

The Molten Salt Test Loop is now the only test facility in the nation that can provide real power-plant conditions and collect data to help companies make commercial decisions about such systems, Ghanbari said.

“It will be used to evaluate components for a molten salt power plant,” she said. “It will show how well systems hold up when immersed in salt at high temperatures.”

Sandia mechanical technologist John Kelton sifts through a bucket of salt beads before they are melted for use in the Molten Salt Test Loop.

In the CSP solar tower system, the lab replaced nearly 6,000 mirrors, which reflect sunlight onto a 200-foot heat-collection tower. The old mirrors, installed in the 1970s, only reflected about 82 percent of the sunlight because of some materials in them.

“The new mirrors now reflect 96 percent, so we’re getting a lot more bang for our buck,” Ghanbari said.

The lab also built a long-range “target” to measure how well the mirror arrays, known as heliostats, beam sunlight over long distances, and how wind and other vibration-causing elements affect that.

“It allows us to measure how much of the heliostat beam stays on target up to one mile away,” Ghanbari said.

Other upgrades include a new optical test lab for CSP components, and a mobile test system for companies that can’t come to Sandia.

Separately, the lab used another $1.8 million in stimulus money to add new DC/AC conversion testing capabilities at its Distributed Energy Technologies Lab. Inverters in customer-owned PV systems tied to the grid, known as “distributed generation,” have been losing about 5 percent of electricity in the conversion process for residential PV, and up to 4 percent on large commercial systems, said project lead Sig Gonzalez. The new testing capabilities could lead to efficiency improvements.

Meanwhile, Sandia’s Materials, Devices and Energy Technologies group is receiving broad industry praise for developing micro-scale solar cells called “solar glitter.” The cells, about the width of a human hair, can be mass manufactured with standard semiconductor micro-scale tools and technologies, said Sandia physicist Vipin Gupta.

The tiny, crystalline silicon cells are about 10 times thinner than conventional PV cells, yet they perform at about the same efficiency. That helps reduce costs and improve performance, while enabling new applications, such as building them directly into flexible products like tents, bags or clothing, or embedding them into more sturdy structures to form the outer shell of cellphones, tablets or laptops.

“They can go into areas where it’s costly to have heavy equipment, such as satellites or rovers on Mars,” Gupta said.

Sandia’s technology transfer office is finalizing plans to license solar glitter to private investors.

The Molten Salt Test Loop is the only test facility in the country that can provide real power-plant conditions and collect data about the interactions of pressure, temperature and flow rates. (COURTESY of SANDIA LABS)

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