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Two New R&D 100 Awards Uphold NREL Winning Streak

Photo provided by Solar Junction

Two New R&D 100 Awards Uphold NREL Winning Streak

Solar cell and cooling technology solve industry problems.

Photo of a man in a white hood, mask, and contamination suit looks through his glasses at a blue white light emanating from the deposition equipment.  An inset photo shows a hand grasping forceps that are holding a round, gold-colored solar wafer.

Solar Junction's SJ3 solar cell is based on NREL's pioneering multijunction work. The large photo shows the molecular-beam epitaxy (MBE) deposition system, and the inset is the completed SJ3 wafer.
Photo provided by Daniel Derkacs, Solar Junction

An illustration of a cross-section of the cell in a vertically elongated cube shape.  On top is a dark gray contact layer, then a gray anti-reflection layer. Below that, colored junction layers are separated with gray tunnel junction layers. The top cell junction 1 layer is blue, the middle cell junction layer is green, and the bottom cell junction layer is yellow.  Below that is a red substrate layer, and at the very bottom is a gray contact layer.

A schematic of the SJ3 multijunction cell highlights the three junctions and their chemical compositions and bandgaps (in electron-volts). The top cell uses the high-energy end of the solar spectrum, and lower cells use correspondingly lower-energy portions of the spectrum.
Illustration provided by Daniel Derkacs, Solar Junction

Illustration of the two stages of DEVAP. The first stage shows the dehumidifier, represented by a layered box, taking in water and outdoor air in the top and outdoor air and return air from the left side.  Liquid desiccant goes in a pipe at the top left corner of the box and comes out a pipe in the bottom right corner. The partly conditioned supply air moves out of the box to the right and to the second stage. The second stage is represented by another, wider layered box.  It receives supply air from stage one from the left and water from the top. Exhaust air exits from the bottom and the fully conditioned supply air exits to the right.

DEVAP consists of two distinct stages: a dehumidifier stage and an indirect evaporative cooling stage.
Illustration by Jason Woods, Eric Kozubal, and Stacy Buchanan, NREL

In 2012, the National Renewable Energy Laboratory (NREL) developed technologies that earned two R&D 100 awards—bringing the total to 52 since 1984. The lab collected trophies for a record-setting, high-efficiency solar cell and a cost-slashing air conditioning technology. These achievements underscore the lab's leadership among national laboratories in renewable energy and energy efficiency research.

This year, NREL and its corporate partners won R&D awards for the following technologies.

SJ3 Concentrator Solar Cell

Problem: Even though multijunction solar cells have higher conversion efficiencies than any other type of solar cell, developers of utility-scale and space applications need cells that are both more efficient and lower in cost to be cost-effective and meet the demand for power.

Solution: NREL, in partnership with Solar Junction, a manufacturer of high efficiency multijunction cells for the concentrated photovoltaic (CPV) market, developed this award-winning technology. Working together, researchers discovered a material that could be used for a bottom junction and that has an optimal bandgap and lattice constant—dilute-nitride alloys incorporating gallium, indium, nitrogen, and arsenic (GaInNAs). The team also used molecular-beam epitaxy (MBE), a manufacturing technique used in the cell phone and solid-state lighting industries, to grow high-performance multijunction cells cost-effectively.

Impact: The SJ3 solar cell has the highest efficiency ever—43.5% at 418 suns—yet a comparable cost. It uses a lattice-matched multijunction architecture that has a near-term potential of developing cells that will approach 50% efficiency. A schematic of the SJ3 multijunction cell highlights the three junctions and their chemical compositions and bandgaps (in electron-volts). The top cell uses the high-energy end of the solar spectrum, and lower cells use correspondingly lower-energy portions of the spectrum.

For more details, see the NREL fact sheet, "Optimal Materials and Deposition Technique Lead to Cost- Effective Solar Cell with Best-Ever Conversion Efficiency."

Considered "the Oscars of Innovation," the R&D 100 Awards have been presented each year since 1963. Through the awards, R&D Magazine identifies and recognizes revolutionary technologies recently introduced to the market. The magazine editors and a panel of technical consultants, university faculty, and industrial researchers evaluate numerous nominated technologies to select the top 100 based on their potential impact. Past award winners have included the flashcube (1965), halogen lamp (1974), liquid-crystal display (1980), anticancer drug Taxol (1993), and HDTV (1998).

Desiccant-Enhanced Evaporative (DEVAP) Air Conditioner

Problem: Air conditioning currently consumes about 15% of the electricity generated in the United States. It is also a major contributor to peak electrical demand on hot summer days, which can lead to escalating power costs, brownouts, and rolling blackouts.

Solution: NREL and its partners, AILR Research, Inc. and Synapse Product Development LLC, combined desiccant-based dehumidification with indirect evaporative cooling to invent the DEVAP air conditioner.

Impact: Estimates show that the DEVAP air conditioner provides superior comfort for commercial buildings. This technology works in any climate at a fraction of the energy costs of conventional air-conditioning equipment, releasing far less carbon dioxide and cutting costly peak electrical demand by nearly 80%. Widespread use of this technology could save billions of dollars in investments and operating costs for our nation's electrical utilities and their customers.

For more details, see the NREL fact sheet, "NREL's Energy-Saving Technology for Air Conditioning Cuts Peak Power Loads Without Using Harmful Refrigerants" and the Continuum news story, NREL Air Conditioner Ready to Change Industry.

Learn more about NREL's Spectrum of Clean Energy Innovation and how the laboratory's capabilities emulate the nature of the innovation process.

The NREL Spectrum of Clean Energy Innovation

Issue 3

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