NREL is conducting tests on the new SkyTrough parabolic trough design atop South Table Mountain for the next several months.

The SkyTrough was developed by SkyFuel, an Albuquerque–based manufacturer, with a research facility near NREL in Arvada, CO. The unit's lightweight glass-free are mirrors made of sheet metal beneath ReflecTech mirror film. The film is a joint invention of NREL and ReflecTech and exclusively licenced from NREL.

"It's unlike any parabolic trough design used so far," said NREL senior engineer Keith Gawlik.

"Our new facility is designed to test the optical efficiency of the unit, which they can't do on their own at SkyFuel," said Gawlik.

The SkyTrough is mounted on NREL's Large Payload Solar Tracker. It supports solar components that require 2-axis tracking. The tracker is capable of carrying a maximum vertical load of 9,000 pounds with a tracking accuracy of 1 milliradian.

The NREL tests will center on validating the SkyTrough's optical performance. According to NREL, a key step in CSP is making sure the light collected in the parabolic trough is accurately converted and focused on the receiver tube so it can heat the transfer oil efficiently.

"Lots of things come into play when focusing light," Gawlik said. "We have to consider the reflectivity of the surface, the accuracy of the surface and then aiming all of the light into the narrow focal line of the receiver tube."

Typically, a parabolic trough operates at nearly 80 percent optical efficiency, and SkyFuel expects its design to function at least as well, while being less expensive to manufacture, transport and maintain. The NREL test will span portions of at least three seasons to explore the unit's performance under a variety of weather conditions and sun angles.