Theoretical Comparative Energy Efficiency Analysis of Dual Axis Solar Tracking Systems

This paper developed a theoretical model substantially based on the principle that only the normal component of solar radiation is actually converted into electrical energy. This theoretical model helped to predict minimum and maximum daily energy gain (compared to static PV system tilted with certain angle) when using dual axis PV solar tracking systems, at any given location on earth without prior experimental data. Based on equations derived from model, minimum and maximum energy gain is computed and summarized in tables of minimum and maximum. Furthermore, the model equations could be used to set up future experimental studies related to the matter.

Three-degree-of-freedom Parallel Manipulator to Track the Sun for Concentrated Solar Power Systems

In concentrated solar power（CSP） generating stations, incident solar energy is reflected from a large number of mirrors or heliostats to a faraway receiver. In typical CSP installations, the mirror needs to be moved about two axes independently using two actuators in series with the mirror effectively mounted at a single point. A three degree-of-freedom parallel manipulator, namely the 3-RPS parallel manipulator, is proposed to track the sun. The proposed 3-RPS parallel manipulator supports the load of the mirror, structure and wind loading at three points resulting in less deflection, and thus a much larger mirror can be moved with the required tracking accuracy and without increasing the weight of the support structure. The kinematics equations to determine motion of the actuated prismatic joints in the 3-RPS parallel manipulator such that the sun＇s rays are reflected on to a stationary receiver are developed. Using finite element analysis, it is shown that for same sized mirror, wind loading and maximum deflection requirement, the weight of the support structure is between 15% and 60% less with the 3-RPS parallel manipulator when compared to azimuth-elevation or the target-aligned configurations.

New Linkage with Linear Actuator for Tracking PV Systems with Large Angular Stroke

This paper focuses on the development of an optimized photovoltaic tracking system involving low-cost, relative simple mechanisms, with linear actuators able to insure strokes comparable with those resulted when using gear rotary actuators. Starting with a rhombus linkage, with a linear actuator on the diagonal used for the elevation motion till 90°, a new performance solution is generated. This new linkage allows large angular strokes by using an asymmetric rhombus and an eccentrically positioned linear actuator. The paper can be divided in three main parts. Firstly the kinematical modeling of the new linkage is addressed, which permits the establishing of the linkage dimensions according to two adjustable parameters （k2, k5）. Using the resulted correlations, in the second part the linkage synthesis algorithm is developed; the steps followed in this algorithm are presented in a numerical application considering a tracked PV platform, where the azimuthal vertical movement is obtained with the new proposed rhomboidal linkage. In the last part of the paper an analysis is done with the aim of determining the PV platform tracking efficiency （which represents the ratio between the received and the available beam solar energy） using the new linkage, in the meteorological conditions of Brasov, Romania implementation site.

Complete Solution of Sun Tracking for Heliostat

A general solution of sun tracking for an arbitrarily oriented heliostat towards an arbitrarily located target on the earth is published. With the most general form of solar tracking formulae, it is seen that the used azimuthelevation, spinning-elevation tracking formulae etc. are the special cases of it. The possibilities of utilizing the general solution and its significance in solar energy engineering are discussed.

Photovoltaic Sensor for the Solar Battery Guidance on the Sun Based on GeS:Sb Layered Crystals

Photovoltaic tracking sensor monitoring the position of the sun in the sky was developed on the basis of GeS:Sb layered crystals. The operating principle of this sensor is based on the phenomenon of photovoltaic effect in GeS:Sb crystals;the magnitude and sign of generated photo-emf depend on the position of the light probe relative to the ohmic contacts, deposited on (001) surface of the crystal.

Tilted global solar irradiance in Bahrain:an experimental study

In the present work,tilted global solar irradiance data are presented and analysed,measured for a period of 1 year on the campus of Bahrain Polytechnic,Kingdom of Bahrain,from both a fixed photovoltaic panel and a moving one via a two-axis solar tracker.The fixed panel faces south with an angle of 26°with respect to the horizontal,coinciding with the local geographical latitude.The second panel is moved by two motors,controlled by a global positioning system and suitable software so that the Sun’s rays are perpendicular to the panel surface.A pyranometer is installed on each panel,recording the tilted global solar irradiance,stored by using a data logger.The analysis of the data obtained shows a 33%solar energy gain on an annual basis for the moving panel(2780 versus 2088 kWh/m^(2) on the fixed panel).More importantly,in June,when the energy demand in Bahrain is elevated due to the increased residential cooling loads,the solar energy received by the moving panel is 54.7%higher compared with that of the fixed panel.On a percentage basis,the increase in solar energy from the moving panel is profound in the early morning and late evening hours.Moreover,the reduction in the solar energy received by the fixed panel from May to June does not appear in the moving panel because of the adjustable orientation of the latter.Throughout the year,the mean daily solar power varies between 0.37 and 0.56 kW/m^(2) for the fixed panel,and 0.45 and 0.70 kW/m^(2) for the moving panel.In winter,solar energy fluctuations are elevated due to erratic weather conditions that present a peak standard deviation of 28%of the corresponding mean.The data presented are useful for potential solar investments in Gulf countries.