High Flux Solar Furnace


National Renewable Energy Laboratory (NREL)

Capability Expert

Judy C. Netter


System Integration

Node Readiness Category

2: High-Temperature Electrolysis (HTE)
1: Solar Thermochemical (STCH)


NREL's HFSF has been in operation since 1990 and consists of a tracking heliostat and 25 hexagonal slightly concave mirrors to concentrate solar radiation. The solar furnace can quickly generate up to 1,800°C over a 1-cm2 area—and up to 3,000°C with specialized secondary optics to generate concentrations greater than 20,000 suns. Flux levels and distributions can also be tailored to the needs of a particular research activity.

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 facility can provide a platform for testing prototypes for solar-electric and solar-chemistry applications.

Capability Bounds‎

NREL's solar furnace is ideally suited for small-scale feasibility studies. It is available for on-sun functional component performance testing and materials testing for photo-electrochemical (PEC) cell and STCH solar receiver.

Unique Aspects‎

NREL's High Flux Solar Furnace (HFSF) is available for on-sun functional component performance testing. For example, the furnace has been used for solar thermochemical hydrogen (STCH) solar receiver and materials testing for over 20 years based on funding through DOE's FCTO. On-sun testing of photo-electrochemical (PEC) hydrogen production cells could also be supported if applicable.

The HFSF is co-located with NREL's internationally renowned Solar Radiation Research Laboratory (SRRL). The SRRL is the home of the world's largest collection of radiometers in continuous operation including pyranometers, pyrheliometers, pyrgeometers, photometers, and spectroradiometers that can provide the solar resource information necessary for characterizing the performance of solar hydrogen components.


NREL's HFSF is used consistently in summer months to fulfill test commitments on current projects. Shorter days in late fall through early spring limit test times. Winter days historically yield the highest direct normal irradiance due to clear skies, yielding excellent test conditions.
We anticipate the solar furnace will be roughly 50% uncommitted in FY17 for testing beyond current commitments.


NREL's HFSF has been used historically for on-sun testing of prototype receiver designs at relevant scales, including those designed to demonstrate solar-to-hydrogen and solar-to-fuels conversion. Tests are performed under realistic, rather than simulated conditions. The facility can be used to support high-flux conditions (design point or accelerated) of components and materials envisioned within the HydroGEN mission.


Aerial view of NREL's High Flux Solar Furnace facility

Aerial view of NREL's High Flux Solar Furnace facility

Watter-splitting reactor

Water-splitting reactor


Continuous On-Sun Solar Thermochemical Hydrogen Production via an Isothermal Redox Cycle NREL/JA-5500-73987

Amanda L. Hoskins; Samantha L. Millican; Caitlin E. Czernik; Ibraheam Alshankiti; Judy C. Netter; Timothy J. Wendelin; Charles B. Musgrave; Alan W. Weimer 2019

Computational modeling and on-sun model validation for a multiple tube solar reactor with specularly reflective cavity walls. Part2:  Steam gasification of carbon. Chemical engineering science, 81, 285–297 Martinek, J., Bingham, C., & Weimer, A. W. (2012).

Atomic layer deposited thin film metal oxides for fuel production in a solar cavity reactor. International Journal of Hydrogen Energy, 37(22), 16888-16894. Lichty, P., Liang, X., Muhich, C., Evanko, B., Bingham, C., & Weimer, A. W. (2012).