Research Papers

Sun-Relative Pointing for Dual-Axis Solar Trackers Employing Azimuth and Elevation Rotations

[+] Author and Article Information
Daniel Riley

Sandia National Laboratories,
P.O. Box 5800, MS 0951,
Albuquerque, NM 87185-0951
e-mail: driley@sandia.gov

Clifford Hansen

Sandia National Laboratories,
P.O. Box 5800, MS 1033,
Albuquerque, NM 87185-1033
e-mail: cwhanse@sandia.gov

1Corresponding author.

Contributed by the Solar Energy Division of ASME for publication in the JOURNAL OF SOLAR ENERGY ENGINEERING: INCLUDING WIND ENERGY AND BUILDING ENERGY CONSERVATION. Manuscript received July 21, 2014; final manuscript received November 24, 2014; published online December 30, 2014. Assoc. Editor: Santiago Silvestre.

The United States Government retains, and by accepting the article for publication, the publisher acknowledges that the United States Government retains, a non-exclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for United States government purposes.

J. Sol. Energy Eng 137(3), 031008 (Jun 01, 2015) (6 pages) Paper No: SOL-14-1211; doi: 10.1115/1.4029379 History: Received July 21, 2014; Revised November 24, 2014; Online December 30, 2014

We present an algorithm to calculate the azimuth and elevation angles for a dual axis tracker to be pointed away from the sun with a desired orientation between the sun and the tracker face. Desired tracker positions are specified in terms of angle of incidence (AOI) and AOI direction, i.e., the direction of the projection of the sun beam onto the plane of the tracker face. This algorithm was developed to enable characterization of the electro-optical response of photovoltaic (PV) and concentrating PV (CPV) modules with anisotropic response to AOI.

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Grahic Jump Location
Fig. 1

Description of solar position angles from and observer on earth's surface

Grahic Jump Location
Fig. 2

(Top) An isometric view of a solar tracker with reference axes. The line on the surface of the cone indicates all possible sun positions with the same AOI (α) relative to the tracker. (Bottom) Direct view of the face of the tracker with β identified.

Grahic Jump Location
Fig. 3

Use of the algorithm to control a tracker at Sandia to orient an aluminum plate with a bolt normal to the plate. The direction of the bolt's shadow is 180 deg from the AOI direction, β.

Grahic Jump Location
Fig. 4

Flowchart to clarify the logical branching of the algorithm and aid in its use




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