Simple estimation of PV modules loss resistances for low error modelling

For practical purposes it can be assumed that the power delivered by a photovoltaic generator that is connected to an MPPT is always maximal. When studying the behaviour of a PV generator working in this way, the most interesting aspect is the evolution of the point of maximum power. So, the analysis of the I-V characteristic must be centred in the area of high voltages. In this situation the five parameter model is very appropriate for characterizing the PV generator.On the other hand, in the case of photovoltaic modules the information currently provided by manufacturers is insufficient to do modelling. Thus, to evaluate the loss resistances it is necessary to use any of the different methods that currently exist.The purpose of this paper is to present a new procedure, based on simplified equations, which allows the estimation of the loss resistances of any PV crystalline silicon module. By simulating the modules with the loss resistances calculated in this way highly accurate results are obtained. Especially in the surrounding of the maximum power point the error is always less than 0.5%.     

Capacitive load based on IGBTs for on-site characterization of PV arrays

This paper describes the practical design of a portable capacitive load based on insulated gate bipolar transistors (IGBTs), which is used to measure the I–V characteristics of PV arrays with short-circuit currents up to 80 A and open circuit voltages up to 800 V. Such measurement allows on-site characterization of PV arrays under real operating conditions and also provides information for the detection of potential array anomalies, such as broken cells or defective connections. The presented I–V load is easy to reproduce and low-cost, characteristics that are within the reach of small-scale organizations involved in PV electrification projects.     

太阳能光伏发电系统光伏阵列保护用熔断器的选择分析

光伏发电系统是由能把太阳光能直接转换为电能的部件和子系统构成。其中的光伏阵列是将入射的太阳辐射能直接转换为直流电能的单元,太阳电池板组成的阵列与光伏阵列连接箱连接,电流经连接箱汇流后输出到逆变器或直接应用环节。太阳电池板组成的光伏阵列约占光伏发电系统总成本的70%,如何保护光伏阵列和充分提高     

AB based solar cells and concentrating optical elements for space PV modules

This paper presents briefly the results of the development of , and GaSb cells manufactured for tandem solar cells, as well as tandems designed for point and line-focus concentrator modules. The maximum efficiency 23–23.8% (25°C, AM0) under 20–100 suns has been reached in the infrared transparent cells with prismatic cover. The efficiency 27.5% under AM1.5, 140 suns conditions has been reached as well. The bottom cells are based on lattice-matched or GaSb homo-junction Zn-diffused structures. The summation of the highest efficiencies measured in the top and bottom cells gave the values 28.8%–29.4% (AM0, 20–70 suns, 25°C) and 33.2% (AM1.5, 100 suns, 30°C). Two types of concentrator photovoltaic modules employing the reflective optical elements have been developed. The first type is based on compound parabolic concentrators, the second one on line-focus parabolic troughs. The estimated specific parameters of these modules with single-junction solar cells are the following: 230–240 W · m⁻² (AM0) and 3 kg · m⁻². The usage of tandem cells will allow to increase specific power of these modules on the value of 20–25%.     

晶体硅光伏组件的检测

我国有丰富的太阳能资源，太阳能光伏发电已不再仅仅用于小功率电源系统，而且广泛用于通信、交通、石油、农村电气化、民用产品等各个领域。1998年我国生产的太阳能光伏发电系统的主要部件——光伏组件产量只有2MW。左右，仅相当于世界总产量的1．3％，到2002年产量已达到100MW。左右，截至到2003年底在我国使用光伏组件装机的太阳能电站达到55MWp。保证太阳能光伏发电系统的质量不仅取决于系统的设计，还取决于构成系统各部件产品的质量。光伏组件作为太阳能光伏发电系统的主要部件，其产品的质量就显得尤为重要。为保证该产品的质量，国家制定了相关的检测标准．本文就光伏组件产品质量的检测作一介绍．     

A power-rating model for crystalline silicon PV modules

A model for the performance of generic crystalline silicon photovoltaic (PV) modules is proposed. The model represents the output power of the module as a function of module temperature and in-plane irradiance, with a number of coefficients to be determined by fitting to measured performance data from indoor or outdoor measurements. The model has been validated using data from 3 different modules characterized through extensive measurements in outdoor conditions over several seasons. The model was then applied to indoor measurement data for 18 different PV modules to investigate the variability in modeled output from different module types. It was found that for a Central European climate the modeled output of the 18 modules varies with a standard deviation (SD) of 1.22%, but that the between-module variation is higher at low irradiance (SD of 3.8%). The variability between modules of different types is thus smaller than the uncertainty normally found in the total solar irradiation per year for a given site. We conclude that the model can therefore be used for generalized estimates of PV performance with only a relatively small impact on the overall uncertainty of such estimates resulting from different module types.     

一种光伏组件寿命的测量方法

给出了组件日发电量和太阳日辐射量的测量方法,采用具有最大功率点跟踪的发电量测试仪测试被测组件和参考组件,通过比较它们日发电量之比与日期的关系,判断被测组件的稳定性,并评估组件的寿命。     

Dual model oriented modeling of monocrystalline PV modules based on artificial neuronal networks

The deep insight into the different elements that compose photovoltaic (PV) systems is capital to boost the optimization of each one of them and consequently, increment of the overall performance of the whole PV systems. In this paper we address the open problem of obtaining empirical accurate models of monocrystalline PV modules in a systematic and unattended fashion. In order to tackle this issue, we used a dual model oriented modeling approach based on artificial neural networks (ANN) due to their advantages, being the generalization capability the most outstanding one. We tried two different model approaches with different input/outputs specifications to learn the electrical behavior of a monocrystalline PV module Atersa A-55 placed on the roof of the Faculty of Engineering of Vitoria-Gasteiz (Basque Country University, Spain). Following these approaches we found two season oriented models of I_PV with a RMSE accuracy of 0.20 mA and 0.26 mA respectively, which is better than the precision of the measurement devices. After comparing these results with the state-of-art ones, we conclude that we have outperformed the previously existing results.     

Enhanced heat dissipation of V-trough PV modules for better performance

A concentrator photovoltaic (PV) module, in which solar cells are integrated in V-troughs, is designed for better heat dissipation. All channels in the V-trough channels are made using thin single Al metal sheet to achieve better heat dissipation from the cells under concentration. Six PV module strips each containing single row of 6 mono-crystalline Si cells are fabricated and mounted in 6 V-trough channels to get concentrator V-trough PV module of 36 cells with maximum power point under standard test condition (STC) of 44.5 W. The V-trough walls are used for light concentration as well as heat dissipation from the cells which provides 4 times higher heat dissipation area than the case when V-trough walls are not used for cooling. The cell temperature in the V-trough module remains nearly same as that in a flat plate PV module, despite light concentration. The controlled temperature and increased current density in concentrator V-trough cells results in higher V_oc of the module.     

Reflection and absorption characteristics of electromagnetic waves for PV modules

In this paper, the authors investigated the reflection and absorption characteristics of a general photovoltaic (PV) module. As a result, the electromagnetic waves could be attenuated only 6 dB in typical PV module. However, if the PV module is installed in the outer wall of buildings, electromagnetic interference is caused by the surroundings. To reduce this electromagnetic interference, the authors suggested a method to absorb electromagnetic wave using multiple PV modules that have deference impedance, and simulation was performed. As a result, it was confirmed that using a typical PV module and the PV module including electronic device, the reflection waves of those PV modules could be attenuated up to 12 dB.     

A novel on-line MPP search algorithm for PV arrays

A novel maximum power point (MPP) search algorithm for photovoltaic (PV) array power systems is introduced. The proposed algorithm determines the maximum power point of a PV array for any temperature and solar irradiation level using an online procedure. The method needs only the online values of the PV array output voltage and current, which can be obtained easily by using just current and voltage transducers. The algorithm requires neither the measurement of temperature and solar irradiation level nor a PV array model that is mostly used in look-up table based algorithms. Satisfactory results were obtained with the proposed algorithm in a laboratory prototype implementation scheme consisting of a PV array computer emulation model, a chopper controlled permanent magnet DC motor, and a DT2827 data acquisition board with the ATLAB software drivers for interfacing     

Development of bifacial PV cells for new applications of flat-plate modules

Bifacial cells have been developed for use in flat-plate static-concentrator modules and bifacial photovoltaic modules. All but one of the fabrication processes are conventional mass production processes, making it possible to produce these cells at low cost. By using 12.5×12.5 cm SOG wafers, bifacial cells with about 15% front- and 10.5% rear-illumination efficiencies have already been developed, and cells achieving higher efficiencies for both surfaces are being developed now. By applying these cells, a bifacial-cell-type flat-plate static-concentrator module showed 82% optical-collection efficiency for normal-incident light with a 2.0 concentration ratio. We have also applied bifacial cells for non-concentrating bifacial modules and developed a new application that reduces the limitations on PV module installation.     

Self-shading losses of fixed free-standing PV arrays

The energy yield of a photovoltaic (PV) system with fixed free-standing PV arrays is affected also by the self-shading effects. The rows of PV modules in arrays may partially shade the PV modules in the rows behind. In this paper the effects of the row distance on the PV system’s energy yield are evaluated. The estimation of the self-shading losses by the irradiation losses simply overestimates the losses; therefore we developed a simulation model to simulate the real energy loss due to shading of the preceding row in a PV system. The model demonstrates that the self-shading energy losses are at commonly used distances between rows from 20 to 40% lower than the irradiation losses at the modules’ bottom considering the shading conditions. The self-shading energy loss is studied in the case of Ljubljana, Slovenia which may refer to the whole Central Europe. To estimate the self-shading losses a technology-and with parameter modifications also location-independent empirical equation based on module-to-cell width ratio was derived and validated.     

Scale-up issues of CIGS thin film PV modules

Photovoltaics cost has been declining following a 70% learning curve. Now the challenge is to bring down the cost of solar electricity to make it competitive with conventional sources within the next decade. In the long run, the module efficiencies tend to reach 80% of the champion cell efficiencies. Using a semiempirical methodology, it has been shown earlier that while the triple junction a-Si:H thin film technology is competitive, CIGS and CdTe thin film module technologies are highly competitive and presently offer the best approach for significantly exceeding the cost/performance levels of standard and non-standard crystalline Si PV technologies. Since 2006, the production of thin film solar cell in the U.S. has surpassed that of c-Si. At present, the production of CIGS PV modules lags considerably behind that of CdTe PV modules. This is mainly because of its complexity. Scale-up issues related to various CIGS preparation technologies such as co-evaporation, metallic precursor deposition by magnetron sputtering and non-vacuum techniques such as ink-jet printing, electroplating or doctor-blade technology followed by their selenization/sulfurization are discussed so as to assist the CIGS technology to attain its full potential. Besides the welcome announcements of large volume production, it is essential to achieve the production cost below $1/Wp in the near term and attain production speeds comparable to CdTe production speeds. Comparable production speeds are expected to be achieved within the next decade. This will enable reduction of CIGS module production costs to ∼65¢/Wp that would be comparable to the CdTe module projected production cost. Additionally CIGS will have a higher efficiency premium.     

晶体硅光伏组件的检测

我国有丰富的太阳能资源，太阳能光伏发电已不再仅仅用于小功率电源系统，而且广泛用于通信、交通、石油、农村电气化、民用产品等各个领域。1998年我国生产的太阳能光伏发电系统的主要部件——光伏组件产量只有2MWp左右，仅相当于世界总产量的1．3％，到2002年产量已达到100MWp左右，截至到2003年底在我国使用光伏组件装机的太阳能电站达到55MWp。保证太阳能光伏发电系统的质量不仅取决于系统的设计，     

Study of bypass diodes configuration on PV modules

A procedure of simulation and modelling solar cells and PV modules, working partially shadowed in Pspice environment, is presented. Simulation results have been contrasted with real measured data from a commercial PV module of 209 Wp from Siliken. Some cases of study are presented as application examples of this simulation methodology, showing its potential on the design of bypass diodes configuration to include in a PV module and also on the study of PV generators working in partial shading conditions.     

Evaluation of performance parameters of PV modules deployed outdoors

This paper evaluates the performance parameters of five photovoltaic (PV) modules comprising crystalline silicon, multi-crystalline silicon and edge-defined film-fed growth (EFG) silicon technologies. This evaluation was accomplished by measuring and analysing the modules' performances during initial, intermediate and final stages of a 17-month test period. The effect of temperature and irradiance on the performance parameters was investigated. Results obtained indicate that some modules exhibited shunting behaviour and that the EFG silicon module experienced moisture ingress, which in part, resulted in 14% performance degradation. An analysis of the results revealed that the moisture ingress effectively reduced the active module area, resulting in reduced photon absorption, consequently reducing the electron-hole generation as indicated by the reduced short-circuit current. In addition, the EFG-Si module's shunt resistance appeared to decrease over the test period. The rest of the modules showed relatively stable performance, information that is crucial to the system designer and consumer.     

串联型集成光伏组件光伏系统的运行电压优化

在串联分布式光伏系统中,若母线电压为固定值,易使分布式最大功率跟踪控制(Distributed Maximum Power Point Tracking,DMPPT)失效,造成功率的损失。通过逆变器可调节母线电压,但调节能力受电网电压的限制。因此,提出了一种新型的电路结构,在光伏组件串联侧和逆变器之间添加全局功率优化器(Global Power Optimizer,GPO),构建串联运行总线,消除了逆变器对原母线电压范围的影响。并在此拓扑基础上,提出了一种变串联运行电压功率优化算法,通过对串联运行电压进行周期性调节,提升了最大功率跟踪控制的性能。仿真结果表明,在光照严重不均的情况下,系统依然快速、稳定的工作在最大功率点处。     

A single procedure for helping PV designers to select silicon PV modules and evaluate the loss resistances

When a photovoltaic system is to be sized, different PV modules are considered. The optimisation of such systems is always the goal, but the choice of the PV module with best performance should also be considered. Nevertheless, selecting a module from catalogue data has certain inconveniences. First, because those data allow only comparisons with absolute magnitudes, the conclusions about which module is the most appropriate is not easy. Second, data provided in catalogues are not sufficient to know the module behaviour under conditions different from standard. This paper deals with the normalisation of the modules data by considering a base that allows for obtaining a “per unit” representation. For modelling and studying the modules under non-standard conditions it is necessary to know series and shunt resistances, but that is not easy. Then, by simulations, it is possible to show the influence of these resistances in the module behaviour.