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Golden Rays – May 2017

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

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Hot Topics

A researcher holds up a highly reflective perovskite wafer between his fingers. The fingers and background are out of focus, but the reflection of his eye in the wafer is sharp.

Perovskite Ink Paints a Path to Commercialization

Perovskite solar cells have shown impressive gains in efficiency over the past several years. However, most state-of-the-art perovskite solar cells contain thin films deposited through spin coating, a precise method that cannot be scaled up for commercial manufacturing. The best cells fabricated using scalable deposition methods, such as blade coating, still lag behind in efficiency.

NREL scientists have developed a new perovskite ink that enables the production of high-efficiency perovskite solar cells using the blade and spin coating methods. Both methods were tested and produced indistinguishable film morphology and device performance. Kai Zhu, his colleagues in NREL's Chemistry and Nanoscience Center, and Yanfa Yan of the University of Toledo presented their new ink composition in Nature Energy.

The NREL team achieved this parity between the spin-coating and blade-coating methods by tweaking the chemical composition of the deposited ink, thus widening the time window for a crucial depositional step from seconds to minutes. The new ink's composition also reduces the time needed for heat treatment. The team demonstrated their new technique by producing a 12.6-cm2 four-cell module with a stabilized efficiency of 13.3%.

An image shows a large battery system, housed inside a shipping container, begin lowered onto a concrete pad by a red crane. A wind turbine from the National Wind Technology Center appears in the background.

Testing Utility-Scale Energy Storage

In late-March, a 1-megawatt, RESolve energy storage system arrived at NREL's National Wind Technology Center (NWTC) to assist research that aims to optimize the grid for wind and solar plants. NREL is partnering with Renewable Energy Systems Americas—the system's manufacturer—to test advanced controls for integrating battery energy storage with renewable energy systems.

As part of that testing, the storage system will be connected directly into the power grid through the NWTC's controllable grid interface. It will also be integrated with a nearby 400-kilowatt photovoltaic system to evaluate its ability to ensure a consistent energy output.

NREL researchers will use the RESolve system to interpret a range of information—from analyzing the performance of individual battery cells to understanding how storage can be controlled at the grid level. Testing frequency regulation, renewable energy integration, and seamless grid-to-island transitions will lay the groundwork for a large-scale rollout of the technology.

Walking on Solar Panels? Stop! (Video)

At first glance, this might look like a clip from the disco floor, but this video was made by NREL researchers to demonstrate why people should avoid walking and kneeling on solar panels.

Solar cells are easy to break, but when they're packaged in a panel, it can be almost impossible to see the damage. A cracked cell affects the panel's power output and the damage can worsen over time. Temperature changes cause thermal expansion and contraction that will pull apart the material around the crack.

To make the damage visible on video, NREL researchers got creative: they ran current through the solar panel and captured the action on an infrared camera.

Must Reads


Projects and Partnerships

  • Three Finalists Selected in Bright Minds Challenge

    After a judging event on April 12—which included two NREL judges—the Bright Minds Challenge has selected its three finalists. These three teams, hailing from Argentina, Brazil, and Tanzania, are using solar energy to extract lithium for batteries from natural brine, to power hearing aids, and to enable pay-as-you-go microgrid distribution systems, respectively.

    NREL is a partner in the first Bright Minds Challenge, which is on the search for innovative solutions and new materials that will fast-forward the movement towards 100% renewable energy. All three finalists will receive expert support, including from NREL staff, with the final winner receiving the equivalent of $100,000 in expert support.

    Learn more about the three finalists on the Challenge's website.

  • Using Micro-Inverter Data to Estimate Solar Resource

    NREL is partnering with Enphase Energy Inc. to test a new method for measuring a location's solar resource, thus predicting the performance of future PV systems. Researchers from NREL and Enphase have developed a low-cost method to measure the amount of solar radiation available in a given area. As the team explains in a recent Solar Energy paper, the energy reported by micro-inverters on existing PV systems can be used to back-solve for the solar resource in that area.

    When using these back-solved solar resource values to predict the performance of future PV systems, the results matched those based on solar resource measurements from top-of-the-line equipment to within 1%. Now, NREL and Enphase Energy Inc. are working to apply the new method to calculate the solar resource using data from 100 PV systems in five metropolitan areas.

  • More Than 200 Attend Photovoltaic Reliability Workshops

    From February 28 to March 2, more than 200 technical experts from 100 companies and 18 countries gathered in Lakewood, Colorado, to participate in the latest PV Reliability Workshop. NREL, Sandia National Laboratories, and Brookhaven National Laboratory hosted the event, which brings together experts to share information leading to the improvement of PV module reliability.

    Participants discussed issues affecting reliability, including degradation rates, hot spots, light-induced degradation in higher-efficiency panels, and standardized methods of documenting data for accelerated testing. The presentations will be publicly posted on the NREL website in about six months. Registration for next year's PV Reliability Workshop will begin in late 2017.

In Touch With NREL Solar

Opportunities to Partner

DuraMAT Releases Solicitation for Letters of Interest

The Durable Module Materials (DuraMAT) consortium is looking for companies that are directly engaged with the PV industry to participate in developing and commercializing new PV module materials. Recently, DuraMAT released a Solicitation for Letters of Interest to support companies in the solar industry who want to conduct research and development on modules and materials with the national labs. Learn more and submit a proposal.

Solar PV O&M Working Group Update and Cost Model Demonstration

The webinar will feature the PV O&M Working Group, administrated by the National Renewable Energy Laboratory (NREL), Sandia National Laboratories, SunSpec Alliance, and Roger Hill, consultant, for the Department of Energy (DOE) SunShot Initiative. Learn more by registering for the webinar on Monday, May 8, 10-11 a.m. MT.


Distributed Solar for Smaller Utilities Webinar

May 18, 2017

DuraMAT Workshop at Bay Area Photovoltaic Consortium Spring Meeting

May 22–23, 2017

Did you know?

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NREL is currently offering 8 diverse internship opportunities for undergraduates, graduates, and faculty members. There are about 200 interns and postdoctoral researchers working to advance NREL's mission. See all of the available internship programs, along with their deadlines, durations, and contact details on the NREL website.