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High-Flux Solar Furnace Facility

NREL's High-Flux Solar Furnace (HFSF) is a 10-kW optical furnace for testing high-temperature processes or applications requiring high heating rates or solar concentration. The unique capability of the HFSF is that it can produce peak solar flux of 250 W/cm2 or 2,500 suns with primary concentrator and higher fluxes with secondary concentrators.

The operational characteristics and size of the facility make it ideal for testing over a wide range of technologies with a diverse set of experimental requirements. The high heating rates create the perfect tool for testing high-temperature materials, coatings on metals and ceramics, and other materials-related applications. The power generated can be used to evaluate many components—such as receivers, collectors, and reflector materials—used in CSP systems.

The facility can provide a platform for testing prototype advanced converters and chemical reactors for solar-electric and solar-chemistry applications. Researchers can also use the HFSF to evaluate and develop state-of-the-art measurement systems for the extreme solar environment.




Basic Specifications of the HFSF. The heliostat is on a 3-axis tracker that tracks the sun and reflects 1 sun of solar (peak flux 240–250 W/cm2) onto the primary concentrator. The heliostat consists of a flat 32-m2 back-silvered, low-iron mirror with 95% solar-weighted reflectivity.


Left: Flux map of focused beam over 10-cm diameter. Right: Flux map of 10×10-cm exit of homogenizer for concentrated photovoltaic application.

The primary concentrator consists of 25 hexagonal facets, 12.5 m2 (135 ft2) overall. The mirrors are spherical mirrors ground to a 14.6 m (47.8 ft) radius of curvature. They are front-surface ultraviolet-enhanced aluminum with 84% solar-weighted reflectivity. The primary concentrator delivers power to the target (at the focal point) of about 10 kW at 1,000 W/m2 direct normal irradiance. The target concentration point is located 7.01 m (23.0 ft) from the center facet.

Several secondary concentrators are available to modify the focal point if the standard peak flux needs to be modified or spread out.

See more detailed specifications on the solar furnace, or contact Judy Netter.

Additional Capabilities. The HFSF also has capabilities related to modeling and materials testing.

  • Modeling. We can determine secondary concentrator requirements and configuration by using SolTrace modeling. If modeling shows a requirement for a special secondary concentrator, NREL can be instrumental in designing and integrating this concentrator into the HFSF test area. For more information on SolTrace modeling, contact Tim Wendelin.

  • Material Testing. The HFSF facility also includes an ultra-accelerated weathering system (UAWS) for testing of outdoor materials. UAWS provides up to 100× ultraviolet concentration to accelerate aging of materials used outdoors. For more information on UAWS, contact Robert Tirawat.