Abstract: A heliostat includes an optical member (e.g., a mirror), a mounting frame under the optical member, a support stand and a hinge assembly. The hinge assembly allows the optical member to pivot about two orthogonal directions relative to the support stand. A drive mechanism adjusts one or both of an elevation angle and a roll angle of the optical member.

Abstract: A system and method for localization and calibration of a heliostat is disclosed. The system comprises a controller and a camera configured to acquire images of a plurality of heliostats. The controller and camera are configured to acquire a first image of the plurality of heliostats, move one of the plurality of heliostats, acquire a second image of the plurality of heliostats, generate a difference image by subtracting the second image from the first image, identify the heliostat that was moved based on the difference image, and calibrate the position or orientation of the heliostat based on the difference image. The difference image is generated by pixel-wise subtraction of the second image from the first image. The pixel-wise subtraction exposes the heliostat and enables the calibration of the position and/or orientation of known heliostat positions.

Abstract: A heliostat for tracking the sun is disclosed. The heliostat comprises a frame (104) with legs (102); an optical assembly (120) configured to hang between the legs of the frame by means of a plurality of wires (130); and a plurality of actuators (520) configured to change the orientation of the optical assembly via the plurality of wires. The optical assembly may include a mirror (122) or photovoltaic panel that tracks the sun, and concrete backing (610). The optical assembly may further include a tracking controller (150) to energize the plurality of actuators, photovoltaic cell (252) configured to power the tracking controller and actuators, cleaning assembly (1710), and reservoir (770) for capturing rain water on the optical assembly. The optical assembly may further include a camera (254) for capturing images of the frame and determining the orientation of the optical assembly based on the images.

Abstract: A solar collector system comprising at least one heliostat and an inflatable cover configured to protectively conceal the at least one heliostat while it tracks the sun. The inflatable cover comprises a flexible membrane, which is transparent and colorless so that sunlight is transmitted through the cover. The cover may comprise an elastomeric material such as ethylene tetrafluoroethylene (ETFE). The solar collector system may further include a pump for inflating the inflatable cover, a pressure relief valve configured to prevent air pressure in the inflatable cover from exceeding a predetermined threshold, and a pressure sensor configured to automatically turn on the pump when the internal pressure falls below a predetermined threshold. The inflatable cover effectively removes wind loading from the heliostats, thus enabling the heliostats to use low-power, less-expensive actuators.

Abstract: A system and method for tracking the sun with a heliostat mirror is disclosed. The solar tracking system comprises: a camera configured to capture high dynamic range images of the sky, a plurality of cameras configured to capture images of the heliostat mirror, and a tracking controller. The images of the heliostat mirror include reflections of the sky. The tracking controller is configured to generate a circumsolar radiance map characterizing the brightness of at least a portion of the sky with the high dynamic range images.