Golden Rays—December 2017

The Solar Newsletter is an electronic newsletter that provides information on NREL's research and development of solar technologies.

Hot Topics

NREL scientists Joey Luther and Erin Sanehira examine a new quantum dot solar cell.

Perovskites Unlock New Quantum Dot Efficiency Record

Since quantum dots emerged as a novel solar cell technology, lead sulfide has dominated efficiency records, reaching a record 12 percent last year. Now, researchers at NREL and the University of Washington have broken that record using a different quantum dot material—cesium lead triiodide (CsPbI3).

The record-setting cell has an efficiency of 13.4 percent and produces an exceptionally large voltage (about 1.2 volts) at open circuit. A high voltage and wide bandgap makes CsPbI3—part of the recently emerging family of halide perovskite materials—an excellent candidate for low-cost, multijunction perovskite cells.

Installers place solar panels on the roof of a commercial building.

Less Guesswork with New Analysis Tool for PV + Storage

Using NREL's new REopt Lite web tool, commercial building owners can evaluate the economic feasibility of grid-connected solar photovoltaics (PV) on their buildings. The web tool identifies both the optimal PV and battery system sizes as well as the dispatch strategy to minimize the life-cycle cost of energy. REopt Lite also estimates the amount of time that a PV and battery system can sustain the site's critical load during a grid outage.

REopt Lite is based on the more comprehensive (and complicated) REopt model that NREL uses to conduct project feasibility analysis for federal agencies, military installations, businesses, and communities. REopt Lite provides access to a subset of REopt's capabilities and allows a broader audience to run their own site-specific renewable energy decision analysis. In 2018, NREL plans to expand REopt Lite, adding additional capabilities for resiliency analysis and providing access to the model via an application programming interface.

Teams calibrate their solar irradiance measurement devices at NREL's Solar Radiation Research Laboratory.

Fighting Cloudy Weather for Solar Irradiance Standards

Each year, scientists and engineers from as far away as South Korea and as nearby as Boulder, Colorado, drive to the top of South Table Mountain to NREL's Solar Radiation Research Laboratory for the NREL Pyrheliometer Comparison (NPC). Once there, the researchers unpack their telescope-like instruments, designed for measuring direct-beam solar irradiance, and point them at the sun—or at least that's how it's supposed to work.

"Usually we have nice weather and can wrap up the data collection during the first week of the event," said NREL researcher Mike Dooraghi. "This is the first year that the weather forced us into the second week. It is the longest NPC we have conducted." The 42 participants from 25 organizations made good use of their downtime, however, by filling the cloudy days with presentations, meetings, and discussions.

Check out more photos from this year's event on Flickr.

Must Reads


Projects and Partnerships

  • UV Light Forges Improved Semiconductors in NREL Lab

    Two NREL researchers have integrated two dissimilar semiconductors into a heterostructure by using light to modify the interface between them. This scheme could allow for the creation of devices composed of different classes of semiconductors. "The real value of this work is that we now understand how light affects interface formation, which can guide researchers in integrating a variety of different semiconductors in the future," said Kwangwook Park, one of the NREL researchers.

  • Where Can Commercial Customers Benefit from PV + Storage?

    In many places, utility demand charges can account for 30 to 70 percent of a commercial customer's electricity bill. As the cost of energy storage falls, many of these customers may find it more economical to install batteries and shift their electricity demand to off-peak times. But which customers will actually benefit? In a new whitepaper, NREL researchers analyze more than 10,000 utility tariffs in 48 states to identify regions with high demand charges. In total, about 5 million commercial customers may be able to cut their energy bills by deploying battery storage to manage peak demand.

  • NREL Multijunction Technology Licensed to Make Lighter, Cheaper PV Cells

     NREL has entered into a license agreement with MicroLink Devices, Inc., to commercialize NREL's patented inverted metamorphic multijunction (IMM) solar cells. The IMM technique licensed by MicroLink Devices enables multijunction III-V solar cells to be grown—with both higher efficiencies and lower costs than traditional multijunction solar cells—by reversing the order in which individual sub-cells are typically grown. By using its proprietary epitaxial liftoff capabilities, MicroLink will be able to make thin, lightweight, and highly flexible IMM solar cells that are ideal for use in unmanned aerial vehicles, space-based vehicles and equipment, and portable power-generation applications.

  • Decades After Developing Technology, NREL Sets New Solar-to-Hydrogen Record

    Revisiting their previous solar-to-hydrogen research enabled NREL scientists to improve the efficiency of a novel process that converts sunlight directly into hydrogen—and to recapture a world record first set at NREL in 1998. The process directly injects electrons, created when sunlight hits PV cells immersed in an acidic electrolyte, to power a water electrolysis reaction. The NREL team not only broke the efficiency record, but they also standardized efficiency measurements for the technology, improving the accuracy of future work.

In Touch with NREL Solar

Opportunities to Partner

PV Training and Assistance for Cities and Counties

NREL is offering a no-cost training and technical assistance program for city and county staff seeking to add solar energy to their facilities. The program is available either in-person or virtually and will launch this winter. Upon completing the program, attendees will receive additional tools and resources and be asked to share what they have learned with five additional cities or counties. NREL aims to assist 50 city and county staff members. The easy, two-page application is due Thursday, November 30th.

NREL is Hiring

Today, NREL has open positions in almost every section of the lab. From postdocs to analysts, engineers to interns, there are more than 120 positions available, including many solar-related positions.

Solar Desalination Funding Opportunity

This funding program will develop novel technologies or concepts using solar thermal energy to assist in creating freshwater from otherwise unusable waters. The U.S. Department of Energy expects to make 7 to 10 awards for a total of $15 million in funding. Concept papers are due on December 4, 2017.

Power Electronics Funding Opportunity

The U.S. Department of Energy has dedicated up to $20 million to early-stage projects to advance power electronics technologies. Advances in power electronics will help grid operators rapidly detect and respond to problems, protect against physical and cyber vulnerabilities, and enable consumers to manage electricity use. Full applications are due December 15, 2017. Concept papers must have been submitted in October.

CSP Gen3 Funding Opportunity

The U.S. Department of Energy announced up to $62 million to support early-stage research in concentrating solar power (CSP) technologies to enable on-demand solar energy. Concept papers were due October 27, 2017. Full applications are due January 16, 2018.


NREL Concentrating Solar Power is on Twitter

Follow NREL's CSP work, along with other work from NREL's Mechanical and Thermal Engineering Sciences Directorate on a new Twitter account.

Did you know?

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It started with a few solar panels and grew into a 45-acre solar farm, making Cochin International Airport in southern India the world’s first 100% solar-powered airport. The airport expects to recover the cost of the project in less than 6 years.