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.     

Non-destructive degradation analysis of encapsulants in PV modules by Raman Spectroscopy

Raman Probe Spectroscopy as a powerful tool for analyzing the degradation behavior of encapsulants in c-Si based PV modules is reported. A non-destructive and quick testing method is needed in order to follow material changes during the aging of PV modules. Two types of c-Si PV modules with ethylene vinyl acetate (EVA) encapsulation have been aged indoors under damp-heat conditions (85% r.h./85 °C) and under combined UV/moisture conditions, respectively. The aged modules as well as a non-aged reference module for each type were analyzed by Raman Spectroscopy. The degradation of the encapsulant was observed, resulting in an increasing fluorescence background, as well as changing intensities of EVA Raman peaks. A lateral non-uniformity of the fluorescence intensity of and the EVA CH stretching vibration intensity ratios, depending on the position above the cell as well as from the aging condition, could be observed and it might be an indicator for the diffusion of water in the encapsulant.     

Application and validation of algebraic methods to predict the behaviour of crystalline silicon PV modules in Mediterranean climates

Predicting both PV module and generator performances under natural sunlight is a key issue for designers and installers. Five simple algebraic methods addressed to predict this behaviour in Mediterranean climates have been empirically validated. Firstly, the calibration in STC of all significant electrical parameters of both a monocrystalline and a polycrystalline silicon PV modules was entrusted to an accredited independent laboratory. Then, a 12-month test and measurement campaign carried out on these modules in the city of Jaén (Spain, latitude 38°N, longitude 3°W) has provided the necessary experimental data. Results show that (a) crystalline silicon PV module outdoors performance may be described with sufficient accuracy – for PV engineering purposes – only taking into account incident global irradiance, cell temperature, and using any one of two simple algebraic methods tried in this paper and (b) regardless the used method, poor results may be achieved if the PV specimens under study are not electrically characterised in STC prior to analysing their outdoors performance. Even so, the methods recommended in (a) perform best.     

Conceptual considerations on PV systems composed of AC modules

AC module technology has become popular and a number of AC module types are commercially available. Although their specifications are clear, it seems that their technological meaning has not yet been well developed. Therefore, the authors tried to create the total concepts of PV systems composed of AC modules. They are abbreviated AC module-composed PV system or ACM-PV. In the paper, the possible structural configurations of simple AC modules and battery integrated ones are classified in principle. System categories are also classified to show their total concept. Necessary electrical terminals and interfaces, voltage matching method between inverter and PV part, and AC module testing methods are also discussed.     

Comparative study of performance degradation in poly- and mono-crystalline-Si solar PV modules deployed in different applications

Data on long-term performance and degradation of field-aged solar photovoltaic modules is widely recognized as necessary for continued technological improvement and market confidence. It is also important that such research should cover various geographical regions of the globe. This paper presents a study on twenty-nine (29) crystalline silicon modules deployed in grid-connected, battery-charging and water-pumping applications. The modules, installed at six different locations in Ghana were aged between 6 and 32 years. Peak power (P_max) losses ranged from 0.8%/year – 6.5%/year. The P_max losses were dominated by losses in fill factor (FF) and short-circuit current (I_sc). Visually observable defects are also reported.     

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.     

Outdoor performance of amorphous silicon and polycrystalline silicon PV modules

The daily watt-hour efficiency (η_Wh) and daily integrated output power (P_Wh) of the a-Si and poly-Si module have been used to examine the performances of both modules on the basis of two years' data accumulated at outdoor conditions. Results from the analysis of experimental data taken under incident solar energy higher than 3.0 kWh/m² per day show that the annual average of η_Wh of the a-Si module is about 95% and 92.5% of its efficiency at STC condition at the first and second year, respectively, while the values are nearly unchanged at about 89% for the poly-Si module. During a one year period, the average P_Wh of the a-Si and poly-Si module was about 60% and 56%, respectively, of their calculated output power at STC condition, so that the P_Wh for each watt-peak (W_p) of the maximum power of a-Si module is about 11% higher than that of the poly-Si module.     

Outdoor testing of PV module temperature and performance under different mounting and operational conditions

Outdoor performance of photovoltaic (PV) modules primarily depends on the instantaneous plane-of-array irradiance (G_poa) and PV module temperature (T_pv). T_pv can be estimated from the ambient temperature (T_amb) and the G_poa as T_pv=T_amb+k_TG_poa. The coefficient k_T depends strongly on the way the PV module is mounted (open rack, ventilated or unventilated roof mounting, etc.), wind speed and also on the module type. In the presented paper, open rack mounted and unventilated roof integrated cases of PV module installation are experimentally and theoretically examined. Linear relationship with k_T is upgraded with a nonlinear one based on the energy balance model and measured data. Nevertheless, T_pv is also affected by the module’s regime of operation. The T_pv dependency on different regime of operation (open-circuit and maximum power point tracking) for two types of PV modules in two regimes is reported. Differences are discussed in light of energy balance equation within thermal management, where impact of the PV module conversion efficiency on T_pv is also shown.     

The risk of power loss in crystalline silicon based photovoltaic modules due to micro-cracks

Micro-cracks in wafer based silicon solar cell modules are nowadays identified by a human observer with the electroluminescence (EL) method. However, the essential question of how the micro-cracks affect the PV module performance has yet to be answered. We experimentally analyze the direct impact of micro-cracks on the module power and the consequences after artificial aging. We show that the immediate effect of micro-cracks on the module power is small, whereas the presence of micro-cracks is potentially crucial for the performance of the module after artificial ageing. This confirms the necessity to develop the means of quantifying the risk of power loss in PV modules with cracked solar cells in their lifetime, in order to enable manufacturers to discard defective modules with high risk of failure while keeping modules with uncritical micro-cracks. As a first step towards risk estimation we develop an upper bound for the potential power loss of PV modules due to micro-cracks in the solar cells. This is done by simulating the impact of inactive solar cell fragments on the power of a common PV module type and PV array. We show that the largest inactive cell area of a double string protected by a bypass diode is most relevant for the power loss of the PV module. A solar cell with micro-cracks, which separate a part of less than 8% of the cell area, results in no power loss in a PV module or a PV module array for all practical cases. In between approximately 12 and 50% of inactive area of a single cell in the PV module the power loss increases nearly linearly from zero to the power of one double string.     

光伏组件测试的复现性详解

随着IEC 61215:2005标准的换版,依据此标准进行的光伏组件测试时的组件功率判定方法也出现了较大变化,其中一处的变化就是在最终功率判定(即Gate No.2判定)时引入了复现性的概念,针对复现性的定义、重要性及算法进行了推演和阐述.     

Mapping the performance of PV modules, effects of module type and data averaging

A method is presented for estimating the energy yield of photovoltaic (PV) modules at arbitrary locations in a large geographical area. The method applies a mathematical model for the energy performance of PV modules as a function of in-plane irradiance and module temperature and combines this with solar irradiation estimates from satellite data and ambient temperature values from ground station measurements. The method is applied to three different PV technologies: crystalline silicon, CuInSe₂ and CdTe based thin-film technology in order to map their performance in fixed installations across most of Europe and to identify and quantify regional performance factors. It is found that there is a clear technology dependence of the geographical variation in PV performance. It is also shown that using long-term average values of irradiance and temperature leads to a systematic positive bias in the results of up to 3%. It is suggested to use joint probability density functions of temperature and irradiance to overcome this bias.     

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.     

一种阴影情况下光伏组件输出特性的计算方法

提出了一种计算阴影遮挡情况下组件输出特性的方法。该方法首先根据流经组件的电流对被遮挡电池及其所在电池串的输出特性进行分析,在此基础上对旁路二极管的伏安特性进行理论分析,进而判定旁路二极管导通状态,从而计算出光伏组件在阴影遮挡情况下的多峰特性。经试验验证,此种方法可精确地模拟复杂遮挡情况下光伏组件的输出特性,对于各种阴影遮挡情况下的峰值点的最大误差在3%以内。该方法较传统的失配情况下基于一个电池单元并联一个保护旁路二极管的计算方法更符合实际,具有较强的实用价值。     

Calculation of the PV modules angular losses under field conditions by means of an analytical model

Photovoltaic (PV) modules in real operation present angular losses in reference to their behaviour in standard test conditions, due to the angle of incidence of the incident radiation and the surface soil. Although these losses are not always negligible, they are commonly not taken into account when correcting the electrical characteristics of the PV module or estimating the energy production of PV systems. The main reason of this approximation is the lack of easy-to-use mathematical expressions for the angular losses calculation. This paper analyses these losses on PV modules and presents an analytical model based on theoretical and experimental results. The proposed model fits monocrystalline as well as polycrystalline and amorphous silicon PV modules, and contemplates the existence of superficial dust. With it angular losses integrated over time periods of interest can be easily calculated. Monthly and annual losses have been calculated for 10 different European sites, having diverse climates and latitudes (ranging from 32° to 52°), and considering different module tilt angles.     

Experimental investigation of wind effects on a standalone photovoltaic (PV) module

The pressure field on the upper and lower surfaces of a photovoltaic (PV) module comprised of 24 individual PV panels was studied experimentally in a wind tunnel for four different wind directions. The results show that the pressure distribution on the module surface is symmetric about its mid-plane for head-on wind (0° and 180°) and asymmetric at other wind directions. The inter-panel gap (which is essential in large PV modules) is found to influence module's surface pressure field. Pressure magnitudes on the module surface were increased with the module inclination angle, as expected. It is also observed that the mean pressure magnitudes on the PV module under smooth wind exposure are higher than those under open terrain wind exposure.     

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，     

一种光伏用POE胶膜交联度的测试方法

提出了一种光伏用POE胶膜交联度的测试方法,即低温溶剂萃取法,萃取时间为7～10 h,萃取温度为40～80℃,烘干温度设置为140℃,真空度≥0.08 MPa,烘干时间为2～5 h。研究表明,采用该方法能快速且准确的测量出POE胶膜共聚物的含量,可为光伏行业中光伏组件封装用POE胶膜的交联度或交联水平的测试提供一种科学实用的测试方法。     

Evaluation of efficiency and degradation of mono- and polycrystalline PV modules under outdoor conditions

This paper presents the experimental results carried out over a period of years of several photovoltaic modules of two basic types, e.g. monocrystalline and polycrystalline, obtained from various sources. These panels were exposed outdoors under the climatic conditions of Bahrain. Our observations show that two of the “first generation” monocrystalline panels completely failed and severe corrosion developed. The rest of the panels show a degradation in efficiency, however polycrystalline modules show a greater drop in output.     

Theoretical analysis and experimental verification of PV modules

This paper introduces a theoretical analysis of the performance of photovoltaic modules under different meteorological conditions and design parameters. Based on the analysis, A FORTRAN computer sub-program has been constructed and connected to TRNSYS simulation program. The present sub-program is executed within the TRNSYS program to compute the different parameters of PV modules. These parameters include short circuit current, open circuit voltage, maximum output power, I-V and P-V characteristics, and efficiency. To verify the present sub-program, an experimental set up has been installed. It includes a group of identical PV modules mounted at different tilt angles and orientations, an electronic load, a weather station, a data acquisition system, and a computer. The comparison between the experimental and theoretical results shows good agreement at different meteorological conditions, tilt angles, and orientations.     

不同技术类型光伏组件的户外发电性能及衰减分析

对在广东省顺德地区(属于亚热带季风气候)运行的异质结(HIT)光伏组件、铜铟镓硒(CIGS)薄膜光伏组件、碲化镉(CdTe)薄膜光伏组件这3种不同技术类型的光伏组件的户外发电性能进行了比较,并对这3种光伏组件的功率衰减情况进行了定量分析.截至2019年12月,上述3种光伏组件的户外累计运行时间长达12年,其室内I-V特...