Seasonal variation analysis of the outdoor performance of amorphous Si photovoltaic modules using the contour map

The effects of module temperature (T_mod) and spectral irradiance distribution on the outdoor performance of amorphous Si (a-Si) photovoltaic (PV) modules were investigated using contour maps. Compared to PV modules based on crystalline Si, such as single-crystalline Si (sc-Si) and multicrystalline Si, a-Si PV modules exhibit complex behavior with seasonal variation. In this study, we statistically analyzed the outdoor performance of a-Si and sc-Si PV modules. The influence of environmental factors on outdoor performance of a-Si PV modules was analyzed for two seasons, spring and autumn, in which the data periods had nearly the same average T_mod and integrated irradiation. The outdoor performance of the a-Si PV module depends on both temperature history and light-induced degradation.     

Ten years outdoor operation of silicon based photovoltaic modules at central latitude of Japan

For the estimation of energy output from photovoltaic (PV) modules, considering the impact of degradation is essential. In this study, the longtime outdoor performance of various types of silicon-based PV modules [single crystalline Si (sc-Si), multi crystalline Si (mc-Si), amorphous Si (a-Si), a-Si/micro crystalline Si tandem, and a-Si/a-SiGe/a-SiGe three-stack (3-stack)] which were installed at the same outdoor exposure condition in Shiga Prefecture, Japan were investigated using Performance Ratio (PR) as an index of performance of PV modules for ten years from 2000 to 2009. Yearly PR and monthly PR were analyzed and degradation rates (DR) were calculated. The DR was different on the kinds of PV modules from 0.404 to 3.51%/year. The a-Si PV module showed the largest DR and the 3-stack PV module had the least trend to degrade. The analysis of the monthly DR indicated that the high DR of the a-Si PV module was due to the quite large DR in summer, whereas the monthly DR of sc-Si and mc-Si PV modules did not differ much from each other throughout the years.     

Impact of environment factors on solar cell parameters of a-Si∥μc-Si photovoltaic modules

The behavior of amorphous silicon∥micro crystalline silicon (a-Si∥μc-Si) tandem-type photovoltaic (PV) module is complex because the output current is limited by the lower current component cell. Also, the outdoor behaviors are not fully understood. The impact of environment factors on solar cell parameters of a-Si∥μc-Si PV module was quantitatively analyzed and the module was compared with other silicon-based PV modules (single crystalline silicon (sc-Si) and amorphous silicon (a-Si)). The contour maps of solar cell parameters were constructed as a function of irradiance and module temperature. The contour map of a-Si∥μc-Si PV modules is similar to that of a-Si modules. The results imply that output characteristics of a-Si∥μc-Si PV modules are mainly influenced by the a-Si top cell. Furthermore, the efficiency of a-Si∥μc-Si PV modules was compared other solar cell parameters and the contour map of efficiency is similar to that of fill factor.     

Impact of spectral irradiance distribution and temperature on the outdoor performance of amorphous Si photovoltaic modules

Performance of photovoltaic (PV) modules is evaluated under the standard test condition, which rarely meets actual outdoor conditions. Environmental conditions greatly affect the output energy of PV modules. The impact of environmental factors, especially solar spectrum distribution and module temperature, on the outdoor performance of amorphous Si (a-Si) and multicrystalline Si (mc-Si) PV modules is characterized. The results show that the output energy of a-Si modules mainly depends on spectrum distribution and is higher under blue-rich spectrum. In contrast, the output energy of mc-Si module is sensitive to module temperature but not to spectrum distribution.     

Difference in the outdoor performance of bulk and thin-film silicon-based photovoltaic modules

Differences in the outdoor performances of bulk (multi- and single-crystalline Si) and thin-film (amorphous Si(a-Si), a-Si/micro-crystalline Si and a-Si/a-SiGe/a-SiGe) photovoltaic (PV) modules are analyzed. The influence of module temperature and solar spectrum distribution on the PV output is clarified. The PV outputs almost only depend on module temperature in bulk-type Si PV modules while that depend both module temperature and spectrum distribution in thin-film ones. Also, the PV outputs of the bulk-type Si PV modules at most frequent condition at outdoor are lower than that at the standard test condition; in contrast, it was the other way round for thin-film ones.     

Estimation of irradiance and outdoor performance of photovoltaic modules by meteorological data

Three environmental factors of irradiance, solar spectral distribution and module temperature greatly affect the performances of photovoltaic (PV) modules. If the environmental factors can be estimated by basic meteorological data (BMD) announced by an official organization in various areas, the performances of PV modules can be estimated easily. In this study, a relationship between the environmental factors and the BMD was analyzed. The performances of Si-based (crystalline Si and thin-film Si) PV modules were estimated by the relationship. As a result, errors between the estimation and actual performances in the crystalline Si and thin-film PV modules were within 1.88% and 0.58% in Kusatsu city, Japan (34°58′N, 135°57′E). This methodology can be useful for rating the performance of PV modules at various areas.     

Investigation of the degradation of a thin-film hydrogenated amorphous silicon photovoltaic module

The degradation of a thin-film hydrogenated single-junction amorphous silicon (a-Si:H) photovoltaic (PV) module has been studied. We investigated the different modes of electrical and physical degradation of a-Si:H PV modules by employing a degradation and failure assessment procedure used in conjunction with analytical techniques, including, scanning electron microscopy (SEM) and thermogravimetry. This paper reveals that due to their thickness, thin films are very sensitive to the type of degradation observed. Moreover, this paper deals with the problems associated with the module encapsulant, poly(ethylene-co-vinylacetate) (EVA). The main objective of this study was to establish the influence of outdoor environmental conditions on the performance of a thin-film PV module comprising a-Si:H single-junction cells.     

Performance of Si-based PV rooftop systems operated under distinct four seasons

We have investigated the electrical energy yield of hydrogenated amorphous silicon (a-Si:H) single-junction and crystalline (c-Si) photovoltaic (PV) rooftop systems operated under distinct four seasons. The impact of the module type and installed tilt angle on the annual electrical energy yield has been monitored and then compared with the data predicted by the computer simulation. Despite a good temperature coefficient and less shading effect of a-Si:H single-junction modules, the energy output gain of the a-Si:H single-junction PV generator is only 2.7% compared to the c-Si PV generator installed using c-Si PV modules. It is inferred that a nominal rated power of the a-Si:H single-junction modules determined by an indoor light soaking test is not suitable for the design of PV systems operated under distinct four seasons. Thus, the nominal rated power of the a-Si:H single-junction PV modules should be determined through a proper outdoor exposure test considering thermal annealing and light soaking effects under various seasonal weather conditions. In addition, it is found that the performance of the Si-based PV rooftop systems operated under distinct four seasons could be improved by simply toggling the tilt angle considering the plane-of-array irradiance and snowfall effect.     

Tilt angle dependence of output power in an 80 kWp hybrid PV system installed at Shiga in Japan

One-year field experience of an 80 kW PV system on a rooftop of the ROHM Memorial VLSI Research Center at the Ritsumeikan University is reported. All kinds of live technology available materials, c-Si, poly Si and a-Si solar cells are installed on the three tilt angles of 26.5° south, horizontal and north 26.5°. Systematic PV performances have been measured from the beginning of June 2000 to the end of May 2001. Measurements were made mainly on DC output power from four kinds of PV arrays; c-Si south side, a-Si of horizontal and poly Si, a-Si north side. It has been shown from analyses of monthly data on each material that almost 70% of with that in the south side in the annual average. In summer a-Si module yields the maximum output power normalized to 1 kWp. On the contrary c-Si module shows larger output in winter. Some other unique results are demonstrated and discussed.     

Flat roof integration of a-Si triple junction modules laminated together with flexible polyolefin membranes

In BIPV design (Building Integrated PV) with crystalline silicon (c-Si) solar cells, ventilation is important in order to keep cells as cool as possible. To allow good ventilation it is therefore generally preferable to mount the modules separated from the existing roof. In the case of sloped roofs, the modules are superimposed onto the existing roof and for flat roofs separated tilted mounting structures designed to withstand wind loads are used instead, but both are not real building integrations.In this paper we analyse the behaviour and the energy yield of a 15.36 kWp PV system based on flexible triple junction amorphous silicon modules laminated together with a single ply roofing system.The PV plant has been integrated on a flat roof of a professional school located south of Switzerland. A significant part of the data analysis is done in comparison with three small open-rack plants (reference plants) installed near the integrated plant.An important result was that the thermally insulated nearly horizontal modules showed temperatures higher than for modules mounted on an open-rack structure, especially for sunny days. This created higher power losses due to negative temperature coefficients. On the other hand, the higher temperature reached the level where the main degradation mechanism of a-Si modules could be reversed and better thermal annealing could be observed. This conclusion was arrived at after a direct performance comparison of the thermally insulated plant and the open-rack a-Si reference plant, which has the same module and orientation as the main plant.In order to better understand the thermally insulated nearly horizontal plant behaviour, we analysed and quantified the irradiation difference and optical losses with respect to a 20° tilted open-rack c-Si power plant. Optical losses for nearly horizontal modules were significant during the winter, partially affecting their low performance.As a main result, the final energy yield of the thermally insulated a-Si plant was almost comparable to a 20° tilted open-rack c-Si power plant, despite the lower irradiance and higher reflection losses with respect to the latter.Accordingly, compared to c-Si modules, the a-Si technology represents a better choice for thermal insulated BIPV.     

Outdoor exposure tests of photovoltaic modules in Japan and overseas

In order to evaluate the reliability and performances of photovoltaic (PV) modules, it is of importance to reveal the characteristics of PV modules in actual use conditions. Outdoor exposure tests of PV modules have been conducted at some sites in Japan and Australia. The purpose of these tests are to evaluate the effects of the starting month of exposure, long term degradation, and heat insulator on the performances of the module efficiencies. Some important results were obtained, for example, the efficiencies of a-Si modules after one year of exposure showed similar tendencies regardless of the starting month of the year. The efficiencies of a-Si modules showed no long term (for six years) degradation. Heat insulator had the effects on the increase of the module temperature and the corrected (by irradiance and temperature) output power. For the outdoor exposure tests with much more severe conditions, the climate conditions of Oman were examined and found to be a suitable place due to its high solar irradiance, temperature, and humidity.     

单面和双面单晶硅光伏组件的发电性能实证

针对p型PERC单面单晶硅光伏组件和n型双面单晶硅光伏组件,利用光伏组件户外实证测试系统,分析了2016年12月15日~2018年7月20日期间,上海市嘉定区某屋顶的地面采用白板背景时双面和单面组件,以及水泥背景时双面组件的等效发电时长,并对白板背景和水泥背景时双面组件较单面组件的发电量增益情况进行了分析;计算了组件的PR值;分析了阴天和晴天时组件最大输出功率与组件背板温度、太阳辐照度和环境温度的关系;最后对比了单面和双面组件运行13个月后的衰减值。该实证结果为单面和双面组件的户外实证发电性能提供了数据支撑,并对双面组件较单面组件的发电量增益情况进行了有效证明。     

A life-cycle analysis on thin-film CdS/CdTe PV modules

Authors have evaluated the life cycle of a thin-film CdS/CdTe PV module to estimate the energy payback time (EPT) and the life-cycle CO₂ emissions of a residential rooftop PV system using the CdS/CdTe PV modules. The primary energy requirement for producing 1 m² of the CdS/CdTe PV module was similar to a-Si PV module at annual production scale of 100 MW. EPT was calculated at 1.7–1.1 yr, which was much shorter than the lifetime of the PV system and similar to that of a-Si PV modules. The life-cycle CO₂ emissions were also estimated at 14–9 g-C/kWh, which was less than that of electricity generated by utility companies.     

Energy matrices analyses of hybrid photovoltaic thermal (HPVT) water collector with different PV technology

In this paper, an attempt has been made to evaluate and compare the energy matrices of a hybrid photovoltaic thermal (HPVT) water collector under constant collection temperature mode with five different types of PV modules namely c-Si, p-Si, a-Si (thin film), CdTe and CIGS. The analysis is based on overall thermal energy and exergy outputs from HPVT water collector. The temperature dependent electrical efficiency has also been calculated under composite climate of New Delhi, India.It is observed that c-Si PV module is best alternative for production of electrical power. Maximum annual overall thermal energy and exergy is obtained for c-Si PV module. The maximum and minimum EPBT of 1.01 and 0.66 years on energy basis is obtained for c-Si and CIGS respectively, whereas on exergy basis maximum EPBT of 5.72 years is obtained for a-Si and minimum of 3.44 in obtained for CIGS PV module. EPF and LCCE increase with increasing the life time of the system.     

Characterisation of PV CIS module by artificial neural networks. A comparative study with other methods

The presence of PV modules made with new technologies and materials is increasing in PV market, in special Thin Film Solar Modules (TFSM). They are ready to make a substantial contribution to the world's electricity generation. Although Si wafer-based cells account for the most of increase, technologies of thin film have been those of the major growth in last three years. During 2007 they grew 133%.On the other hand, manufacturers provide ratings for PV modules for conditions referred to as Standard Test Conditions (STC). However, these conditions rarely occur outdoors, so the usefulness and applicability of the indoors characterisation in standard test conditions of PV modules is a controversial issue. Therefore, to carry out a correct photovoltaic engineering, a suitable characterisation of PV module electrical behaviour is necessary. The IDEA Research Group from Jaén University has developed a method based on artificial neural networks (ANNs) to electrical characterisation of PV modules. An ANN was able to generate V–I curves of si-crystalline PV modules for any irradiance and module cell temperature. The results show that the proposed ANN introduces a good accurate prediction for si-crystalline PV modules performance when compared with the measured values. Now, this method is going to be applied for electrical characterisation of PV CIS modules. Finally, a comparative study with other methods, of electrical characterisation, is done.     

Uniqueness verification of solar spectrum index of average photon energy for evaluating outdoor performance of photovoltaic modules

To analyze the effect of a spectral irradiance distribution of solar spectra on the outdoor performance of photovoltaic (PV) modules, an index for the spectral distribution is needed. Average photon energy (APE) which represents the average energy per photons included in a spectrum is one of these. In this study, the uniqueness of APE to the spectral irradiance distribution was statistically analyzed to assure that an APE value uniquely yields the shape of a solar spectrum. The similar methodology adopted in International Electrotechnical Commission to rate the spectral matching of a solar simulator was used for the analysis. The results showed that an APE value yielded a spectral irradiance distribution with quite small standard deviation. The analysis using APE showed that the outdoor performance of crystalline Si PV modules depended almost only on a module temperature, while that of amorphous Si ones mainly depended on APE. The behaviors were reasonable considering from the operation mechanisms of the PV modules. These results demonstrate that APE is a reasonable and useful index to describe the spectral irradiance distribution for evaluating the outdoor performance of PV modules.     

Fabrication technology for large-area a-Si solar cells

The fabrication process technology for large-area a-Si photovoltaic (PV) modules and their performance are reviewed. Our present technology enables us to provide 10% efficient large-area submodules with a stabilized efficiency of 8.5%. To study the practicability of the a-Si solar panels, we carried out an outdoor test for our a-Si modules. The results show that the a-Si solar PV modules generate power very efficiently in outdoor systems. The advantage of the a-Si modules under outdoor uses is presented and discussed.     

Performance of Silicon Heterojunction Photovoltaic modules in Qatar climatic conditions

We report on the performance of two cell technologies: Silicon Heterojunction (SHJ) and conventional diffused junction n-type mono-crystalline silicon Photovoltaic (PV) arrays, under a harsh environment condition with high temperature and dust accumulation, typical to Qatar. A comparison of the energy yield and Performance Ratio (PR) at plane of array global irradiance as well as module temperature (T_mod) of the two technologies is presented. The SHJ arrays showed a higher energy yield as compared with the conventional arrays thanks to the higher efficiency of the SHJ. The results showed also that dust accumulated on PV modules may cause a drop in the PR of up to approximately 15% if the module is not cleaned for one month. Scheduled module cleaning or raining will return the PR close to its initial value.     

Improved artificial neural network method for predicting photovoltaic output performance

To ensure the safety and stability of power grids with photovoltaic (PV) generation integration, it is necessary to predict the output performance of PV modules under varying operating conditions. In this paper, an improved artificial neural network (ANN) method is proposed to predict the electrical characteristics of a PV module by combining several neural networks under different environmental conditions. To study the dependence of the output performance on the solar irradiance and temperature, the proposed neural network model is composed of four neural networks, it called multi- neural network (MANN). Each neural network consists of three layers, in which the input is solar radiation, and the module temperature and output are five physical parameters of the single diode model. The experimental data were divided into four groups and used for training the neural networks. The electrical properties of PV modules, including I–V curves, P– V curves, and normalized root mean square error, were obtained and discussed. The effectiveness and accuracy of this method is verified by the experimental data for different types of PV modules. Compared with the traditional single-ANN (SANN) method, the proposed method shows better accuracy under different operating conditions.     

Analysis of thermal and electrical performance of semi-transparent photovoltaic (PV) module

Building-integrated PhotoVoltaic (BIPV) is one of the most fascinating PV application technologies these days. To apply PV modules in buildings, various factors should be considered, such as the installation angle and orientation of PV module, shading, and temperature. The temperature of PV modules that are attached to building surfaces especially is one of the most important factors, as it affects both the electrical efficiency of a PV module and the energy load in a building. This study investigates the electrical and thermal performance of a semi-transparent PV module that was designed as a glazing component. The study evaluates the effects of the PV module's thermal characteristics on its electrical generation performance. The experiment was performed under both Standard Test Condition (STC) and outdoor conditions. The results showed that the power decreased about 0.48% (in STC with the exception of the temperature condition) and 0.52%(in outdoor conditions, under 500 W/m²) per the 1 °C increase of the PV module temperature. It was also found that the property of the glass used for the module affected the PV module temperature followed by its electrical performance.