Facilities

NREL's large-payload solar tracker supports testing of solar components that require tracking the sun in elevation and azimuth. The site can be used to supplement metrology activities that require 2-axis tracking for simultaneous calibration of solar radiation measurement instrumentation. The large-payload solar tracker can carry a maximum vertical load of 9,000 lbs with a tracking accuracy of 1 mrad. For information about NREL’s large-payload solar tracker, contact Guangdong Zhu.

A parabolic trough up to 16 m long can be mounted in the large-payload solar tracker. Photo by Pat Corkery, NREL

NREL's High-Flux Solar Furnace is a unique 10-kW optical furnace that harnesses concentrated sunlight to test high-temperature processes or applications that require high heating rates or solar concentration.

The High-Flux Solar Furnace contains a tracking heliostat and 25 hexagonal concave mirrors that concentrate solar radiation to deliver 10 kW of thermal power to a focal area about 4 in. (~10 cm) in diameter within the laboratory control room.

The High-Flux Solar Furnace's hexagonal mirrors concentrate the sun as reflected off a tracking heliostat. Photo by Judy Netter, NREL

The Thermal Storage Materials Laboratory supports research and development of advanced heat-transfer fluids and thermal energy storage media for next-generation CSP systems. NREL researchers are working to identify fluids with thermal and oxidative stability to withstand extreme operating conditions, such as temperatures up to 800ºC, and that can function as advanced thermal storage media. The laboratory combines a work area for basic wet chemistry with extensive thermal and spectroscopic analysis capabilities, for synthesis of fluids in gram quantities and immediate evaluation of their thermal behavior.

At extreme operating temperatures, heat-transfer fluids can be very corrosive to tanks and piping. Learn more about how NREL researchers are evaluating the corrosion and degradation stability of containment materials for heat-transfer fluids. For information about NREL's Thermal Storage Materials Laboratory, contact Judith Vidal.

Judith Vidal works with a differential scanning calorimeter to characterize thermal fluids at high temperatures for corrosion-resistant metal coatings. Photo by Dennis Schroeder, NREL

NREL's Receiver Test Laboratory houses a parabolic trough receiver test stand used to analyze steady-state, off-sun thermal losses of receivers used in solar parabolic trough power plants. These receivers, also called heat-collection elements, are long absorber pipes enclosed in a sealed, insulating glass envelope to reduce heat loss. In the test stand, electric heaters and thermocouples are first placed inside the receiver being tested. The power use of the heater is recorded at a desired absorber temperature. This procedure is repeated for several different absorber temperatures to generate heat-loss curves for a receiver. Research continues to help reduce heat-collection elements optical losses and to further reduce receiver heat loss at elevated temperatures. For information about NREL's Receiver Test Laboratory, contact Greg Glatzmaier.

A receiver for a solar collector is mounted on this heat-loss test stand and tested for heat loss at temperatures between 100°C and 500°C. Photo by Frank Burkholder, NREL

The Advanced Optical Materials Laboratory provides analytical and measurement capabilities for developing and testing optical properties and performance of materials used in CSP systems. We can measure a range of feature sizes (from nanometers to meters) and sample sizes (from millimeters to tens of meters).

In addition to measurement of optical properties, the laboratory houses indoor equipment to test CSP modules and systems under simulated and accelerated conditions, including sunlight, various temperature and humidity levels, rain, freeze/thaw, hail, and salt spray. Testing chambers use a xenon arc light that accelerates light exposure by a factor of 7.5. The chambers run 24 hours a day, 7 days a week to replicate specified conditions on an ongoing basis. NREL indoor accelerated weathering facilities include a high-bay accelerated testing facility, optical mechanical characterization laboratory, mechanical characterization equipment, and an accelerated exposure testing laboratory.

For information about NREL’s Advanced Optical Materials Laboratory, contact Guangdong Zhu.

An NREL engineer aligns a mirror used for parabolic troughs. Photo by Dennis Schroeder, NREL

NREL uses both natural outdoor and accelerated exposure tests to determine CSP system materials’ rates of degradation, estimated lifetimes, potential failure mechanisms, and strategies for mitigation. NREL’s outdoor ultra-accelerated weathering system (UAWS) contains an ultraviolet concentrator. Its parabolic dish features special mirror facets that concentrate and focus the sun's ultraviolet rays, capable of simulating 10 years of ultraviolet damage in just 2 months. Studies can be conducted on a variety of surfaces—from automotive paint and building materials to coatings on solar panels. The UAWS won an R&D 100 Award for its ultra-high intensity and acceleration, high fidelity to actual sunlight, and reasonable exposure temperatures. For information about the UAWS, contact Guangdong Zhu.

The outdoor UAWS system allows the study of aging on materials, accelerated at up to 100 times. Photo by Judy Netter, NREL

Thermal Scout is an NREL-developed receiver survey system that uses a global positioning system and infrared camera to rapidly inspect receivers in parabolic trough CSP systems for performance issues. It uses an infrared  camera, global positioning system technology, and computer software. The portable system attaches to a standard vehicle that is driven down each row of a parabolic trough plant, using global positioning system data to automate infrared imaging and analyze temperatures of all receivers in the field. Thermal Scout is a fully automated device that allows operators to safely and accurately evaluate more than 6,000 receivers per day, without impacting normal plant operation.

Thermal Scout tracks and analyzes in real time using a global positioning system and an infrared camera. Photo by Dennis Schroeder, NREL

Distant Observer (DO) is an optical measurement tool designed to quickly identify costly flaws in parabolic trough solar collector fields. DO combines remote-controlled photography and metrology to capture and evaluate images of receiver-tube reflections taken from different angles. DO identifies two types of optical efficiency problems in a parabolic trough: reflector slope errors and misalignment of the receiver absorber with the focal line of the parabola. With either ground-based or drone-driven implementation, DO can help plant operators spot and swiftly rectify errors to keep CSP plants operating at maximum efficiency.

DO uses a small-scale commercial drone with a specialized camera to enable researchers to find flaws in parabolic trough mirrors. Photo by Benjamin Ihas, NREL

SOFAST, or Solar Optical Fringe Alignment Slope Technique, is an automated concentrator characterization system that assesses the quality of mirrors for solar applications. A video camera and computer capture and analyze fringe patterns from a reference target pattern in the reflected image of a solar concentrator to identify slope as well as slope errors. Data acquisition is extremely fast, consisting of the time needed to take a few digital photos of the virtual image of the target as seen in the concentrator under test. SOFAST was originally developed by Sandia National Laboratories. Under a Department of Energy-funded partnership agreement, it was licensed to NREL and adapted for trough mirror-facet characterization.

For information about NREL's solar-field characterization tools, contact Guangdong Zhu.

SOFAST captures and analyzes patterns in the reflected image of a solar concentrator to identify slope errors in an automated fashion.

All of our CSP test capabilities are available to industrial, university, and government researchers. For further information, or to arrange a technical service agreement to use one of our laboratory facilities, contact Mark Mehos.