应用于高原山地光伏电站的平单轴光伏发电跟踪系统的优化

对应用于高原山地光伏电站的平单轴光伏发电跟踪系统进行了优化研究.高原山地光伏电站因采用平单轴光伏发电跟踪系统时,清晨和傍晚太阳高度角较低时前、后排光伏组串会相互产生阴影遮挡,由此现象入手,从反阴影遮挡跟踪策略、平单轴光伏发电跟踪系统对其基础的破坏、平单轴光伏发电跟踪系统可靠性等方面分析了目前采用的常规平单轴光伏发电跟踪...     

光伏支架成本及选型分析

以长沙地区为例，对采用不同类型光伏支架时光伏电站的占地面积、发电量、运行成本、平准化度电成本(LCOE)进行了分析，并分析了不同场景下适用的光伏支架类型。分析结果显示：1)从发电量差异系数来看，双轴跟踪式光伏支架的发电量差异系数最高，单轴跟踪式光伏支架的次之，固定式光伏支架的最低。2) LCOE从低到高依次为：水平单轴跟踪式光伏支架<固定式光伏支架<垂直单轴跟踪式光伏支架<斜单轴跟踪式光伏支架<双轴跟踪式光伏支架。3)当光伏电站项目以经济性最优为考量标准时，建议选择平单轴跟踪式光伏支架。4)当光伏电站项目以装机容量最大为考量标准时，建议选择固定式光伏支架。本研究方法适用于中国各个地区光伏电站的光伏支架成本及选型分析。     

跟踪式光伏发电系统研究

根据某地实测的太阳辐射数据,仿真比较了配备有单轴跟踪和双轴跟踪等4种跟踪控制的光伏发电系统与固定式光伏发电系统的太阳辐射利用率。并在此基础上对4种跟踪系统的跟踪角控制规律及跟踪控制方式进行了详细的分析,得出倾纬度角单轴跟踪系统控制规律最为简单,算法实施更为实用的结论。同时,也在理论上证明了采用步进式控制方式的跟踪系统能够在保持较高太阳辐射利用率情况下简化控制系统设计,有利于工程设计及应用。     

天文算法与倾角传感器反馈相结合的光伏跟踪系统设计

将光伏组件和平单轴跟踪光伏支架相结合,通过相应操作可实现光伏组件的追日跟踪。在利用GPS提供的数据的基础上,提出了一种将天文算法和倾角传感器反馈相结合的光伏跟踪系统。该系统采用闭环控制方式,在正跟踪模式的基础上引入了逆跟踪模式,还包括固定模式及手动模式,其会根据不同的状况采用不同的工作模式,并能根据不同地理位置、日期、天气来调整平单轴跟踪光伏支架的工作状态;其在正跟踪阶段时的跟踪角度误差在±1°以内,在早晨、傍晚及极端天气时能够避免阴影遮挡光伏组件,有助于提高光伏电站的整体经济效益。     

基于光敏二极管传感器三维阵列的光伏跟踪误差检测研究

光伏跟踪系统可提高光伏发电系统的发电效率,但由于光伏跟踪系统的运行机构及运动控制算法等存在不稳定性,常会导致其运行效果不理想,跟踪精度难以保障。为实现光伏跟踪系统跟踪误差的现场检测,设计了一种基于光敏二极管传感器三维阵列的光伏跟踪误差检测装置,该装置主要包括1个由多个光敏二极管传感器以三维阵列规则镶嵌构造的圆球体和主控制系统等;并设计了基于激光水平仪的传感器标定方案,实现传感器初始值偏差校正,提升检测装置一致性,实现对单轴或双轴光伏跟踪系统跟踪误差的自动检测。经设备试制及测试验证,结果表明：该检测装置可满足光伏跟踪系统跟踪误差检测精度需求,能够准确在线检测单轴、双轴光伏跟踪系统在不同情况下的跟踪误差。     

关于不同单轴跟踪方式的对比分析

针对4种太阳能单轴跟踪方式,即传统的东西轴向方式、南北轴向方式以及偏离角轴向方式和倾斜角轴向方式,提出了通过计算新参数(瞬时利用系数和日利用系数)来分析对比各种单轴跟踪方式的方法,该方法以太阳光的入射余角为参变量,并考虑了端部损失面积的影响。以南京地区一项关于槽式集热系统的设计为例,根据所建模型进行了相应计算,分析了该系统采用各种单轴跟踪方式时所呈现出的特点。该文所建模型可用来指导实际设计中,在各种地区条件下按需求选择最为合适的单轴跟踪方式。     

不同安装方式时双面光伏组件发电系统的理论建模分析

基于PVsyst仿真软件,以青海格尔木市为模拟地点,考虑了场景反射率、组件前后间距、安装方式与高度、逆变器匹配设计等因素,在固定倾角式、平单轴跟踪两种安装方式下,分析对比了双面光伏组件与常规光伏组件的辐射接收量、发电量、系统效率和度电成本,并研究了场景反射率对双面光伏组件发电量的影响和此类光伏发电系统逆变器的限光损失。仿真结果表明,在固定倾角安装或平单轴跟踪的安装方式下,采用双面光伏组件的发电系统比采用常规光伏组件的发电系统的发电量理论上平均可提升10%以上,且随着场景反射率的增加而增加;当场景反射率为60%时,度电成本可降低14%,具有较高的经济效益,在降本增效方面具有较大的技术价值。     

各类光伏方阵面辐照度的计算

光伏方阵有多种运行方式,如固定安装、单轴太阳跟踪、双轴太阳跟踪等,正确计算光伏方阵面任意时刻的辐照度,从而正确计算光伏方阵面上的辐射量始终是困扰光伏系统设计人员的课题。本文从太阳和地球的运行规律及基本的球面三角关系推导出了不同光伏方阵运行方式下的数学模型,为正确计算不同运行方式下光伏方阵面(包括背表面)的辐照度提供了理论依据,使光伏系统的设计者能够正确、方便地计算不同光伏方阵面的辐射量和光伏系统的发电量。     

双轴跟踪和单轴南北向跟踪CPV/T系统的热电性能研究

分别搭建了采用双轴跟踪和单轴南北向跟踪这2种跟踪方式的聚光光伏光热(CPV/T)系统实验平台,并对不同跟踪方式下的系统的热、电性能进行了测试.在实验条件基本相同的情况下进行了多次测试,结果表明,双轴跟踪C P V/T系统的平均光电转换效率和平均光热转换效率分别为13.0％和52.6％,均高于单轴南北向跟踪C P V/T...     

东北地区固定式与单轴跟踪式光伏发电量对比

以吉林省乾安县光伏试验电站为例,基于近1年每3min发电量数据,统计了固定式、单轴跟踪式、单晶硅电池、多晶硅电池的发电量,在剔除缺测和不合理数据的基础上,对比了不同方式、不同材料下的光伏发电效率,并分析了固定式与单轴跟踪式的优劣与性价比。结果表明,单轴跟踪式光伏发电效率较高,多晶硅效率比单晶硅高,单轴式多晶硅系统性价比最高。     

A multipurpose dual-axis solar tracker with two tracking strategies

This paper deals with a multipurpose dual-axis solar tracker that can be applied to solar power systems. This tracker employs a declination-clock mounting system that locates the primary axis in east-west direction. Based on this mounting system, normal tracking strategy and daily adjustment strategy are developed for flat Photovoltaic (PV) systems and Concentrating Solar Power (CSP) systems respectively. While the former strategy keeps the tracking errors smaller than the pre-specified values, the latter one simplifies the tracking process by adjusting the primary axis once a day and driving the secondary axis to rotate at a constant speed of 15°/h. Results of the accuracy test indicate that the tracking error of the normal tracking strategy is within 0.15°. The other strategy may have greater tracking errors, but its annual average cosine loss for flat PV systems is estimated to be below 1.3%. Furthermore, in the test on the output of the PV modules, it is found that the average energy efficiency of the normal tracking PV, compared with the fixed PV, is more than 23.6%. And the average energy efficiency of the daily adjusted PV is more than 31.8%. Results of the experiment show that the two tracking strategies are both feasible for the developed tracker.     

Experimental evaluation of V-trough (2 suns) PV concentrator system using commercial PV modules

V-trough photovoltaic (PV) concentrator systems along with conventional 1-sun PV module is designed and fabricated to assess PV electricity cost ($/W) reduction. V-trough concentrator (2-sun) system is developed for different types of tracking modes: seasonal, one axis north–south and two axes tracking. Three design models based on these tracking modes are used to develop the V-trough for a 2-sun concentration. Commercially available PV modules of different make and types were evaluated for their usability under 2-sun concentration. The V-trough concentrator system with geometric concentration ratio of 2 (2-sun) increases the output power by 44% as compared to PV flat-plate system for passively cooled modules. Design models with lower trough angles gave higher output power because of higher glass transmittivity. PV modules with lower series resistance gave higher gain in output power. The unit cost ($/W) for a V-trough concentrator, based on different design models, is compared with that of a PV flat plate system inclined at latitude angle (Mumbai, φ=19.12°).     

Simulation model for sizing of stand-alone solar PV system with interconnected array

Solar PV arrays made of interconnected modules are comparatively less susceptible to shadow problem and power degradation resulting from the aging of solar cells. This paper presents a simulation model for the sizing of stand-alone solar PV systems with interconnected arrays. It considers the electricity generation in the array and its storage in the battery bank serving the fluctuating load demand. The loss of power supply probability (LPSP) is used to connote the risk of not satisfying the load demand. The non-tracking (e.g., fixed and tilted) and single-axis tracking aperture arrays having cross-connected modules of single crystalline silicon solar cells in a (6×6) modular configuration are considered. The simulation results are illustrated with the help of a numerical example wherein the load demand is assumed to follow uniform probabilistic distribution. For a given load, the numbers of solar PV modules and batteries corresponding to zero values of LPSP on diurnal basis during the year round cycle of operation are presented. The results corresponding to the surplus and deficit of energy as a function of LPSP are also presented and discussed to assess the engineering design trade offs in the system components.Furthermore, a simple cost analysis has also been carried out, which indicates that for Delhi the stand-alone solar PV systems with fixed and tilted aperture arrays are better option than those with single-axis tracking aperture (with north–south oriented tracking axis) arrays.     

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.     

Analysis of the yield and production cost of large-scale electrolytic hydrogen from different solar technologies and under several Moroccan climate zones

The objective of this paper is to conduct an analysis of the green hydrogen production by the mean of water electrolysis from different solar energy systems and under different climate conditions in Morocco. To this end, simulation of four solar power plants configurations -with a nominal capacity of 100 MW_e from different technologies (fixed PV, 1 axis tracking PV, 2 axis tracking PV, and Stirling Dish) coupled with a PEM electrolyzer has been done. For the sake of precision, 3 years average of high quality meteorological data measured in-situ and at 5 different locations were used as simulation inputs. To have an idea about the potential of Morocco in the green hydrogen production market, we benchmarked the simulation results against the ones from Almeria, Spain and Stellenbosch, South Africa. Results show that for almost all sites, the 1 axis tracking PV system is the optimal technology -from techno-economic aspect-for green Hydrogen production in Morocco, even though the 2 axis tracking PV systems can generate the highest amounts of hydrogen (~4500 Tons/year), the fixed PV has the lowest LCOH₂ (5.8 $/Kg) and the Stirling Dish is the most efficient one (~12%). Besides, Morocco can be considered as a very competitive country for green hydrogen production (especially for PV technology) with an LCO_H2 of 5.57 $/Kg, against 5,96$/Kg in Southern Spain and 6,51$/Kg for south Africa.     

Performance comparison of a double-axis sun tracking versus fixed PV system

In the present study, performance results of two double axis sun tracking photovoltaic (PV) systems are analyzed after one year of operation. Two identical 7.9 kWp PV systems with the same modules and inverters were installed at Mugla University campus in October 2009. Measured data of the PV systems are compared with the simulated data. The performance measurements of the PV systems were carried out first when the PV systems were in a fixed position and then the PV systems were controlled while tracking the sun in two axis (on azimuth and solar altitude angles) and the necessary measurements were performed. Annual PV electricity yield is calculated as 11.53 MW h with 1459 kW h/kWp energy rating for 28 fixed tilt angle for each system. It is calculated that 30.79% more PV electricity is obtained in the double axis sun-tracking system when compared to the latitude tilt fixed system. The annual PV electricity fed to grid is 15.07 MW h with 1908 kW h/kWp for the double axis sun-tracking PV system between April-2010 and March-2011. The difference between the simulated and measured energy values are less than 5%. The results also allow the comparison of different solutions and the calculation of the electricity output.     

Aquatic photovoltaic facility for Catalina Island

A feasibility study, design, and cost estimate have been completed for a 1 MWe photovoltaic (PV) facility which would float on an inland reservoir at Catalina Island. If built, this would be one of the largest PV operating facilities to date and also the first floating PV system. The modular installation consists of 250 floating platforms, each supporting 430 ft² of flat panel PV cells. Three tracking systems were considered; a two-axis tracking, a one-axis tracking, and a non-tracking system. The non-tracking and one-axis tracking systems were carried through the final design stage. The one-axis system was most cost effective. The total cost of the one-axis tracking system is about $4.0 million; the cost of the non-tracking system is about $3.7 million. The levelized energy costs for the two systems are about $0.37/kWh and $0.42/kWh respectively. This facility would provide 25% of Catalina's yearly peak energy demand; reducing the amount of diesel fuel used for power production. The aquatic environment provided difficult and unusual design criteria.     

A fast and low cost analog maximum power point tracking method for low power photovoltaic systems

Low power photovoltaic (PV) systems are commonly used in stand-alone applications. For these systems, a simple and cost-effective maximum power point tracking (MPPT) solution is essential. In this paper, a fast and low cost analog MPPT method for low power PV systems is proposed. By using two voltage approximation lines (VALs) to approximate the maximum power point (MPP) locus, a low-complexity analog MPPT circuit can be developed. Theoretical derivation and detailed design procedure will be provided in this paper. The proposed method boasts the advantages such as simple structure, low cost, fast tracking speed and high tracking efficiency. To validate the correctness of the proposed method, simulation and experimental results of an 87 W PV system will also be provided to demonstrate the effectiveness of the proposed technique.     

Optimal sizing of array and inverter for grid-connected photovoltaic systems

Optimum PV/inverter sizing ratios for grid-connected PV systems in selected European locations were determined in terms of total system output, system output per specific cost of a system, system output per annualised specific cost of a system, PV surface orientation, inclination, tracking system, inverter characteristics, insolation and PV/inverter cost ratio. Maximum total system output was determined for horizontal, vertical and 45° inclined surfaces for a low efficiency inverter for sizing ratios of 1.5, 1.8 and 1.3, respectively; and for a medium efficiency inverter with sizing ratios of 1.4, 1.5 and 1.2. PV surface orientation and inclination have little impact on the performance of a high efficiency inverter. For different PV tracking systems and for different inverter characteristics, the optimum sizing ratio varied from 1.1 to 1.3. The PV/inverter cost ratio and the PV and inverter lifetimes have significant impact on the optimum PV/inverter sizing ratio. A correlation relating optimum sizing ratio and PV/inverter cost ratio has been developed; the correlation coefficients were found to be functions of insolation and inverter type. The impact of PV/inverter sizing ratio on PV array performance was less when PV array has a much higher cost than the inverter. The optimum sizing ratio for PV/inverter cost ratio of 6 and low efficiency inverter system varied from 1.4 to 1.2 for low to high insolation sites. For a high efficiency inverter system, the corresponding variation was from 1.3 to 1.1.