Design of a Linear Actuator Driven Solar Tracker for High Concentration Photovoltaics Technologies

Abstract

Abstract-A CPV solar tracker design is described using CAE tools. A virtual wind tunnel simulation and finite element analysis software to calculate the stress and deformation is used. A 'tilt-roll' tracker employs an inexpensive linear actuator and dampers system to drive the tilt axis, also a bar mechanism driven with another linear actuator in the 'roll' axis is utilized. The process to calculate the aperture angle losses caused by the wind drag is discussed.Index Terms-Solar tracker, CPV, finite element analysis. I. INTRODUCTIONThe CPV technology transforms solar radiation to electric energy. This process requires tracking the apparent moving of the sun along the day. To that purpose, it must integrate an automatic structure capable to track the sun, and place the optics of the concentrator in a way that the direct solar radiation is always focused on the modules during the day [1].According to Angel [2], HCPV technology should compete successfully against the fossil based electricity generation dropping total installation costs respect to flat PV systems. There are various types of solar tracking mechanisms described in literature. Mousazadeh [3] analyzed the principles and methods of solar tracking to maximize the power output of solar systems, finding that the most popular and efficient tracking architectures are the polar axis and altazimuth systems. Actually most of the commercially available CPV systems use a 2 axis tracking in an altazimuth configuration with a pedestal tracker followed by the "tilt-roll" or "polar" configuration.The first tracking control systems employed analog sensors to detect the sun and align the mechanism toward it, based on shadowing technologies with light sensors, integrating a closed loop control with motor that drove the mechanism. The developing of low cost microcontrollers motived the appearance of solar tracking systems, that no longer require Manuscript received May 8, 2015; revised July 30, 2015. This work was supported by the Mexican Science Council (CONACYT) with the grant "Fondo Sectorial de Sustentabilidad Energética" for the Mexican Energy Innovation Center (CEMIEsol) in the P03 project.Christian Dá vila-Peralta and Ricardo Rodrí guez-Carvajal are with the Industrial Engineer Department, University of Sonora, Hermosillo, SON 83000Mexico (e-mail: cdavila@vinculacion.uson.mx, ricardo@industrial.uson.mx).Rafael Cabanillas-López is with the Department of Chemical Engineering and Metallurgy, University of Sonora, Hermosillo, SON 83000 Mexico (e-mail: rcabani@iq.uson.mx).Rafael Garcí a-Gutié rrez is with the Physics Research Department, University of Sonora, Hermosillo, SON 83000 Mexico (e-mail: rgarcia@cifus.uson.mx).sensors and which are based only on the digital calculation of high precision analytics equations of solar positioning [1].The function of a concentration solar tracker is align permanently the aiming axis of the concentration system with the local solar vector, in a way that the maximum power output is produced. In flat PV systems the solar tracking wil...

Functionality Analysis of Electric Actuators in Renewable Energy Systems—A Review

“…At night, the solar panel moves back to the initial position through the linear actuator as the motor rotates anti-clockwise and the piston goes inside the housing. The sun changes its azimuth angle position as seasons change, and the panel cannot change the tilted position [12]. Hence, the panel cannot receive perpendicular sun rays, thereby decreasing the yield.…”

“…For example, for a moving panel of +45 • , more consumption is noted than −45 • rotation due to wind pressure during positive angle tracking. The 'tilt' and 'roll' (shown in Part (b) of dual-axis tracking in Figure 2) tracker employs a linear actuator and dampers [12]. Linear movement with a bar mechanism in the 'roll' axis finds use in the concentration of photovoltaic technologies, and two different heliostat-based tracking methods are discussed [49].…”

“…Rotary to linear motion is achievable using a mechanical transmission unit, called linear motion actuators, which are better in accuracy than rotary actuators, compact in size, and easy to use in many applications such as solar tracking systems [12], where solar panels can track the sun's apparent motion; solar furnace systems [13], where the motion required to control the sun-rays by moving shutters; solar heater systems [14], where sun rays are concentrated on oil pipes (called active area) placed over the parabolic solar panels; solar cleaning systems [15,16], where two motions are performed (viz., x-axis and y-axis motion) to clean the whole solar panel; small-scale wind systems [17], where actuators are used as protection devices in high wind speeds; wave systems [1,2,18,19], where actuators are used in the conversion of wave motion to linear and rotary motion for energy generation; and bio-energy systems [20][21][22][23], where actuators automate the operation of geologically distributed systems.…”