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NREL Successfully Transfers VSHOT Technology to Solar Industry

March 12, 2009

A side-view photo of a large, silver parabolic trough in the middle of a snow-covered field.

The SkyTrough solar collector is one example of industry partners using NREL's VSHOT technology for research and development.
Credit: Pat Corkery

A tool used for testing utility-scale solar collectors is heating up the solar thermal industry. NREL has received numerous inquiries from industry partners to acquire VSHOT (Video Scanning Hartmann Optical Test) for research and development. VSHOT uses lasers to quickly characterize the optical surfaces of solar concentrators for both linear and point focus systems.

SkyFuel, Inc., an Albuquerque-based solar manufacturer with a research facility near NREL, requested VSHOT support from NREL several times during the development of their SkyTrough collector. SkyTrough uses lightweight glass-free mirrors made of aluminum sheet metal beneath ReflecTech® mirror film. This highly reflective, silver-metalized film is lighter and less expensive than the glass mirrors that are traditionally used. The film is a joint invention of NREL and ReflecTech, and exclusively licensed from NREL.

Solar Systems, an Australian company developing dish and central receiver concentrating photovoltaic optical systems, became the first industry partner to implement a VSHOT system into their facility. NREL provided design, installation, and training assistance to Solar Systems via a cooperative research and development agreement (CRADA). Since that time, Solar Systems has used VSHOT to check the quality of hundreds of heliostat mirrors to be used in a central receiver demonstration plant.

Most recently, Abengoa Solar became the second industry partner to implement a VSHOT system into their facility under a CRADA with NREL. NREL assisted Abengoa Solar in designing, building, and assembling their VSHOT system. Validation tests were completed on an Abengoa Solar 2.2 meter aperture trough collector. Data taken on the collector by both the NREL and Abengoa VSHOT systems were compared, with results varying under the range of uncertainty for the system at less than 0.1 mrad. This validation ensured that the system was operating as designed and that Abengoa engineers were properly trained in the operation.

NREL will continue to provide VSHOT support to the solar thermal industry, but having optical characterization capability in-house has proven to be the most efficient testing method for the industry. For this reason, NREL is working on a licensing agreement for VSHOT that will allow industry partners to develop their own tool in-house. The increasing demand for concentrating solar power, coupled with the visibility of these recent successes, has uniquely positioned NREL as a world-class leader in optical testing. As a result, future opportunities to provide this type of expertise and assistance are expected.