A simple and efficient sun tracking mechanism using programmable logic controller

To increase the unit area illumination of solar ray on PV panel, it is required to track the sun throughout the day. So to reach the goal various type of sun tracking mechanism is already developed but in this paper we designed two different types of sun tracking mechanism: single axis and dual axis tracking using programmable logic controller (PLC) as it has numbers of unique advantages like??it is faster, reliable, requires less maintenance and reprogrammable. A comparative study between those two systems is also presented in this paper. The whole system has been designed and tested using GE, FANUC PLC.     

太阳能等照度带聚焦菲涅耳透镜研究

为了提高聚光发电时太阳电池的光电转换效率,从提高太阳电池表面会聚光强分布的均匀性入手,对传统平板型线聚焦透镜进行改进,提出一种用于聚光光伏发电的等照度带聚焦菲涅耳透镜设计方法。带聚焦菲涅耳透镜分为奇数个单元,每个单元宽度与太阳电池宽度相等,单元内所有尖劈角φ相等并将太阳辐射等宽度折射至太阳电池表面,从而实现各单元透过的太阳能等照度叠加。最大聚光比由光伏电池宽度、透镜与太阳电池间距以及透镜材料折射率决定。对带聚焦和线聚焦两种透镜聚光条件下电池表面温度分布情况进行比较分析,验证了等照度带聚焦透镜设计的可行性。     

Adaptive sun tracking algorithm for incident energy maximization and efficiency improvement of PV panels

In recent times, sun tracking systems are being increasingly employed to enhance the efficiency of photovoltaic panels by constantly tracking the elevation and azimuth angles of the sun. In this paper, a novel adaptive digital signal processing and control algorithm is presented that optimizes the overall PV system output power by adjusting the position angles of the solar panel on both the elevation and azimuth axes. Since the proposed approach is adaptive in nature, the optimal position angles for the solar panel are iteratively computed using the adaptive gradient ascent method, until the incident solar radiation, and hence the output power is maximized. Furthermore, a Taylor’s series approximation is employed for generating a unique optimal position angle increment/decrement at each iteration. Simulation results show that the proposed technique demonstrates fast convergence and excellent tracking accuracy at all times of the day.     

A high precision tracking system based on a hybrid strategy designed for concentrated sunlight transmission via fibers

This paper investigates a high precision tracking system that adopts the coordinate calculation algorithm and a photosensitive sensor. This system is designed to satisfy the precision requirement in sun tracking for a concentrated sunlight transmitting system via optical fibers. This system is based on a two-stage tracking process, which consists of a coarse adjustment based on the coordinate calculation algorithm and a fine adjustment using a specially designed photosensitive sensor. The core of the photosensitive sensor is a photodiode matrix that could exactly detect the position of the sunlight focal spot via lens focusing. A predictive control process based on the running trend of sun traces will begin once the fine adjustment is completed. The tracking process is steady and accurate because of the predictability of sun traces based on the coordinate calculation algorithm and the acuteness of the photodiode matrix. The highest tracking precision depends on the compactness of the photodiode matrix and has no limits in the accuracy of the coordinate calculation algorithm. The proposed system can track the sun's focal spot with a position precision of less than 0.3 mm, which is the space between the adjacent photodiodes. The tracking angle precision is determined by the ratio of the position resolution of the photodiode matrix to the focal length, and reaches 0.1°.     

Innovative design of cassegrain solar concentrator system for indoor illumination utilizing chromatic aberration to filter out ultraviolet and infrared in sunlight

Many applications and related studies of solar energy have been focused on guiding sunlight into the indoors for illumination purposes. To achieve this objective, one of the approaches is the use of a high efficiency solar concentrator based on cassegrain construction with sun tracking system. However, exposure to UV in sunlight has been proved to be hazardous to humans, and the heat content of IR degrades illumination quality. In order to solve the two problems, we develop an innovative cassegrain solar concentrator system utilizing the theory of chromatic aberration by a chromatic lens to reduce UV and IR. A dispersion model to consider the impact between the chromatic lens and a guiding fiber is also proposed. As a result, the system can filter out UV completely and reduce IR by half. Further, the chromaticity coordinates of collected light for illumination is almost equal to sunlight, and the color difference is so small that the two appear equal to the human eye.     

Performance of Cylindrical Parabolic Collector with Automated Tracking System

Parabolic solar collector collects the radiant energy emitted from the sun and focuses it at a point. Parabolic trough collectors are the low cost implementation of concentrated solar power technology that focuses incident sun light on to a tube filled with a heat transfer fluid. However, the basic problem with the cylindrical parabolic collector without tracking was the solar collector does not move with the orientation of sun. Development of automatic tracking system for cylindrical parabolic collectors will increase solar collection as well as efficiency of devices. The main aim of this paper is to design, fabricate and analyze the performance of parabolic collector with automated tracking system. The automated tracking mechanism is used to receive the maximum possible energy of solar radiation as it tracks the path of sun. The performance of the parabolic trough collector is experimentally investigated with the water circulated as heat transfer fluid. The collector efficiency will be noted.     

LiMoNAED: a limited motion, non-shading, asymmetric, ecliptic-tracking dish

The conventional design of a parabolic dish for a small solar conversion system places the receiver along the line between the center of the dish and the sun. This forces the receiver to move in a large arc during tracking, and produces some shading of the dish. In some applications, such large movement of the receiver is not acceptable. A new concentrator design is proposed for small systems with a constraint of limited mobility of the receiver. This is accomplished by using a first polar axis and a second axis that is aligned with the normal to the ecliptic plane. The new design features limited motion of the receiver, with inclination changing only within ±23.45°; off-axis reflector to eliminate shading; constant rotation speed in both axes; and constant flux distribution on the receiver.     

Feasibility of solar tracking systems for PV panels in hot and cold regions

Solar tracking systems would probably increase the efficiency of a PV module, but when and where. There are many factors that affect the performance of PV panels, especially crystalline silicon panels, e.g. overheating due to excessive exposure to solar irradiance in a hot climate as in Sunbelt countries. So, it could be the case that a tracking system is not necessary for a Sunbelt country. The objective of this research is to determine mathematically the performance of a PV panel as a function of tracking the sun and the operating conditions. The used mathematical model is validated experimentally and then applied for several environments, i.e. hot as well as cold regions. It has been found that the gain in electrical energy from tracking the sun is about 39% in case of a cold city as Berlin, Germany. While the gain in energy does not exceed 8% in case of a hot city as Aswan, Egypt, due to overheating of the PV panels. However, if the energy needed for running the tracking system, which ranges from 5% to 10% of the energy generated, is included in this analysis then tracking the sun will not be feasible in hot countries.     

基于复合控制的塔式太阳能跟踪控制装置设计

针对塔式太阳能热发电站中定日镜跟踪装置的跟踪精度不高、构建成本较大等问题,提出采用将遗传算法的选择机制与吸热塔能量变化的反馈机制相结合的方式对光热电站的太阳能跟踪控制系统进行改进.在光热电站的少数几台定日镜上配备光电检测元件,并以其控制角度为基准控制其他定日镜的角度调整.采用DSP(digital signal processing)为控制核心,完成了跟踪控制器的通讯框架及控制系统的硬件电路设计.实验表明,该方案在保证光热电站整体控制精度的基础上,减少了光电检测元件安装数量和电站构建成本,并保证了视日轨迹跟踪控制时的自动调整能力.     

A computer tracking system of solar dish with two-axis degree freedoms based on picture processing of bar shadow

The sun tracking system of a solar dish based on computer image processing of a bar shadow is investigated. This is done by using a camera to obtain the optimized picture of a bar shadow on a screen by solar dish displacements. This system is independent respect to geographical location of the solar dish and periodical alignments such as daily or monthly regulations. Furthermore, the operation of the system is independent respect to the initial configuration and the start time situation.     

Design,modeling and testing of a standalone single axis active solar tracker using MATLAB/Simulink

This paper presents the design, modeling and testing of an active single axis solar tracker. The compactness of the proposed solar tracker enables it to be mounted onto the wall. The solar irradiance is detected by two light-dependent resistor (LDR) sensors that are located on the surface of the photovoltaic (PV) panel. The smart tracker system operates at different modes to provide flexibility to accommodate different weather conditions and preference for different users. The PV panel rotates automatically based on the sun irradiance during the day while at night; the system is in ‘sleep’ mode in order to reduce the energy consumption. A computer model of the standalone solar tracker system is first modeled using MATLAB?/Simulink?. The efficiency over the fixed solar panel, the power generated and the types of PV systems to achieve the required level of efficiency can be determined before actual implementation. The experimental testing shows some agreement with the simulation results.     

Review on Development of Small Point-Focusing Solar Concentrators

The technology of small point-focusing concentrator of solar energy has been developing rapidly in recent years owing to its compact structure and high collecting efficiency. This report presents important developments of small point-focusing concentrator in the past decade. This kind of solar concentrator refers to the parabolic dish concentrator, the point-focusing Fresnel lens, and the Scheffler reflector. Technological advances of these concentrators and the related performances have been presented. There are three main mirror fabrication technologies for dish concentrator, which are high polishing metal, silver-glass mirror and vacuum-membrane. Polymethyl methacrylate is widely used as material in Fresnel lens. Many scholars have proposed new lens shape to improve the uniformity of focusing. The Scheffler reflector has a characteristic of fixed focus, but its design parameters are not perfect so current research focuses on the theoretical calculation of the mirror. In addition, typical applications of the small point-focusing concentrator in photovoltaic system, solar thermal system, solar chemical system, and day-lighting system are summarized. Upon listing the important publications in open literature, a category of main applications of such kind of solar collector is provided based on the working characteristics of the system.     

Concentrating solar module with horizontal reflectors

A non-sun-tracking concentrating solar module is described that is designed to achieve photovoltaic (PV) systems with higher generation power density. The proposed concentrating module consists of a solar panel having a higher tilt angle than that of a conventional one and with a solar reflector placed in front of the solar panel on a downward inclination angle towards the panel. As a result of this configuration, the solar panel receives reflected as well as direct sunlight so that maximum irradiance and short-circuit current were increased. This configuration is expected to reduce the area required for solar panels, resulting in lower cost PV system.     

Experimental investigation of effect of variation of mass flow rate on performance of parabolic dish water heater with non-coated receiver

Concentrated solar collectors have high efficiency. Therefore, when concentrating collectors are used for water heating application, the system yields higher efficiency. From a hot climate perspective, there is a huge potential available for low-cost solar water heating systems. With the system described in this paper, the needs of hot water in the domestic sector can be fulfilled instantly. Authors used the parabolic dish collector for instant water heating. This paper describes the effect of variation of mass flow rate on performance of the parabolic dish water heater prototype. Design of the solar parabolic dish collector consists of a novel truncated cone-shaped helical coiled receiver made up of copper at focal point. This prototype was evaluated for its performance during the month of April and May 2010.     

采用微功耗控制器提高光伏效率

该文从理论上分析了采用太阳自动跟踪控制装置可提高太阳转换效率的空间；并阐述了采用不同于传感器方式的定时跟踪法的电路实现原理。这种电路不仅省去传感器和相关电路的能耗，更重要的是在该电路中可以实现最省电的休眠工作模式，使采用太阳自动跟踪控制装置后提高转换电能成为现实。该文还对比了固定安置的太阳电池板和采用了太阳自动跟踪控制装置的太阳电池板在相同条件下的转换效率。结果得出采用定时太阳自动跟踪装置的光伏发电系统能大幅度提高转换效率。     

Application of one-axis sun tracking system

This paper introduces design and application of a novel one-axis sun tracking system which follows the position of the sun and allows investigating effects of one-axis tracking system on the solar energy in Turkey. The tracking system includes a serial communication interface based on RS 485 to monitor whole processes on a computer screen and to plot data as graphic. In addition, system parameters such as the current, the voltage and the panel position have been observed by means of a microcontroller. The energy collected is measured and compared with a fixed solar system for the same solar panel. The results show that the solar energy collected on the tracking system is considerably much efficient than the fixed system. The tracking system developed in this study provides easy installation, simple mechanism and less maintenance.     

A comprehensive simulator for assessing the reliability of a photovoltaic panel peak power tracking system

When designing a maximum power point tracking (MPPT) algorithm, it is often difficult to correctly predict, before field testing, the behavior of this MPPT under varying solar irradiation on photovoltaic (PV) panels. A solution to this problem is to design a maximum power point trackers simulator of a PV system used to test MPPT algorithms. This simulator must have the same role as the MPPT card of the PV panel and thus will fully emulate the response of a real MPPT card of the PV panel. Therefore, it is a good substitute to help to test the peak power trackers of the PV system in the laboratory. This paper describes a simple peak power trackers simulator of the PV system which has a short response time thus, can be used to test MPPT algorithms under very rapid variation condition. The obtained results and the theoretical operation confirm the reliability and the superior performance of the proposed model.     

Design of a new three-degree of freedom spherical motor for photovoltaic-tracking systems

Photovoltaic (PV) panels directly convert the solar energy to electrical energy. The amount of electrical energy converted by PV panels mainly depends on incident solar radiation. Sun tracking systems can be used to maximize energy production since they ensure keeping the photovoltaic panels perpendicular to the incoming solar radiation. Spherical motors, which have the linear and circular movement ability in three independent dimensions, can be used for precisely tracking the sun as a solution. In this study, a spherical motor controlled by a micro-controller is designed for a PV-tracking system with the ability to move on two axes. Performance of PV-tracking system over a fixed tilted one is evaluated for the climate condition of Denizli, Turkey. The designed sun tracking system is observed to be improving this performance apparently using the output voltages obtained for one day.     

Performance improvement study of an integrated photovoltaic system for offshore power production

Sustainable energy is one of the main options for resolving energy problems and climate change issues. Solar energy is one of the main promising renewable energy sources, which can be captured and converted to electrical energy through photovoltaic (PV) panels. In the open literature, it is shown that having two PV panels integrated into a back‐to‐back configuration placed on naturally reflective surfaces provides the potential of doubling the total power produced by a single‐faced PV panel with the appropriate location and orientation. This paper presents a case study of two‐PV panel systems for offshore power production. The relevance to offshore has the water surface as the reflective surface to produce power from the back facing panel. The city of Ottawa in Canada is selected as the location for a case study. Various conditions and operating parameters are considered in assessing the performance of the proposed system, including solar radiation intensity, system orientation, time of year in terms of months, and the variations in parameters throughout the day. The assessment of the proposed system is carried out through modeling and simulating the proposed double PV panels in the COMSOL Multiphysics software. It is found that the minimum improvement in the total power production over the single face conventional PV is 38% in January for the east‐facing PV front face. For the two PV systems, the optimal overall power production for the various time conditions and orientations, at the specified location, is found to be the north orientation of the PV panel. In this case, the power it produces is 89% of that of the east orientation. A similar trend is observed for the single‐faced PV panel, where the north‐facing PV provides 62% of what it could produce in the east‐facing orientation.