Search

8th World Conference on Photovoltaic Energy Conversion; 577-579, In the race of ultra-high performance modules and the integration of novel cell architectures for bifacial configuration, many efforts are required in order to ensure module reliability and maintain low BOM cost, leading to research of new material families and configuration among PV module backsheet. Although, PVF and PET based backsheets are in use since several decades with well-established testing methods [1], new materials, surface treatments and manufacturing methods, such as co-extrusion, are rapidly emerging in the PV backsheets field. Therefore, the new backsheet samples require new testing methods and characterization strategy since their structure and physical properties differ from the commonly used backsheets in PV industry. In this paper, we present a three-stage investigation strategy on nine commercial backsheets intended to be integrated in heterojunction (SHJ) PV modules manufactured by 3SUN [2]. We characterize three different groups of backsheets: first group containing a coextruded PP backsheet, the second group covers PET based backsheets containing aluminum laminated layer and the third group about laminated PET based backsheets without aluminum layer. First stage is material level testing (optical, mechanical, adhesion, water absorption and tensile strength) enabling rapid ranking based on backsheet intrinsic properties. Second stage is accelerated aging testing in mini-module configuration while third stage is full-sized module testing. The material characterization allowed the conclusion that adhesion properties seem to have the most influence on final module behavior while we need to highlight that only the WVTR of backsheet material cannot predict the PV module behavior predictions in DH testing and adhesion strength plays a critical role.

37th European Photovoltaic Solar Energy Conference and Exhibition; 994-996, In this study, Light and Elevated Temperature Induced Degradation (LETID) and Potentially Induced Degradation (PID) of heterojunction (HJT) modules and cells sensitivity are tested. LeTID is known to affect PERC modules and some evidences of LeTID in HJT modules have recently been reported. Carrier Induced Degradation and Light Induced Degradation are two different methods to test LeTID sensitivity. Both tests were carried out on modules with PERC and HJT cells. A small loss of 2.5% is pointed out for some PERC modules whereas the HJT modules tested presented no LeTID. Similarly, PID test for 96h shows no loss for HJT modules.

37th European Photovoltaic Solar Energy Conference and Exhibition; 890-893, A premium photovoltaic module technology with high efficiency, high reliability, and low LCOE has been industrialized in Europe by Enel Green Power through the AMPERE project. An innovative full-scale automated 200MWp/y production line of SHJ bifacial cells and modules has been started up in 2019 at the Enel Green Power 3SUN Fab in Catania (Italy). In this paper, we report the investigations performed on two low interconnection solutions meeting the low temperature requirements of HJT technology that have been investigated in terms of performance, production costs and reliability: the BusBar/ribbons interconnection technology with Electrical Conductive Adhesive (ECA) and the SmartWire Contacting Technology (SWCT) developed by Meyer Burger. First, the cell metallization and the interconnection designs have been optimized. Then results have then been validated for full-size (72 cells) modules by IEC61215 certification and extended Damp Heat (DH, 85°C, 85%RH) and Thermal Cycling (TC, -40°C + 85°C) tests, leading to complete certifications of both approaches.

36th European Photovoltaic Solar Energy Conference and Exhibition; 224-228, Silicon heterojunction solar cells are bifacial by nature and their bifaciality coefficient can be easily tuned, from almost 0 for mono-facial cells to typically 90% for bifacial cells, and even 100% but at the expense of the conversion efficiency. For operation in outdoor conditions offering extra light at the backside (BIFI >0), the effective performance of bifacial systems was estimated from the trade off between the cell efficiency and bifaciality. The efficiency of rear-emitter cell decreases with bifaciality and strongly drops for very high bifaciality, because of the use of limiting amorphous layers, especially too thin at backside, and the use of too resistive or too shading metal grids. Thus, an optimum can be found for a given BIFI. Varying cell bifaciality by screen printed grid dissymmetry, the system output in a large range of BIFI is maximum for cell bifaciality ranging from 85% to 90%, typically corresponding to front side metal grid pitch around 2mm and backside pitch from 0.6 to 0.9mm. For a given backside to front side dissymmetry of cell efficiency related to deposited thin layers, the use of optimal metal grid can offer 0.5% relative energy production gain. Considering specific applications where symmetrical print is preferred, the optimal grid pitch is around 1.5mm. For mono-facial systems, it was found that the use of bifacial cells gives a benefit thanks to embedded reflection in glass-back-sheet modules. The optimization of cell bifaciality pointed out in this work must also be considered with silver paste costs: saving when moving to higher bifaciality or a balance between extra cost and higher performances when dense grid for low bifaciality is preferred.

36th European Photovoltaic Solar Energy Conference and Exhibition; 235-238, We report on recent results obtained within the HETNA project, a collaboration between CEA-INES and Enel Green Power for the deployment of silicon heterojunctions solar cells and modules technologies in the production lines at 3SUN 2.0 site. SHJ cells and modules produced on the CEA-INES pilot lines show narrow efficiency distributions and good response with material and process variations: cells average efficiency ranges from 21.2% to 21.8% with the four busbars design while module peak power ranges between 366W to 374W. Increasing number of busbars from 4 to 5 enabled fill factor (FF) improvement by 0.7% abs. at both cells and modules levels without affecting the module reliability after thermal cycling. Finally, we present best cell and module (72 cells, bifacial) results obtained in 2018 reaching 23.9% and 388.4W respectively.

31st European Photovoltaic Solar Energy Conference and Exhibition; 1984-1988, The Laboratory of Solar Energy and Energy Saving located in a hot climate area and the Laboratory of Photovoltaic Modules in a temperate climate zone, lead a common research program on the behavior of PV modules and the energy production according to the climate. For these purposes, the same outdoor characterization facilities have been mounted in the two laboratories. Then, the same silicon modules of different technologies have been installed on both platforms where the I-V curves as well as climatic parameters are continuously measured. Furthermore, electrical models are developed to analyze the data and each technology performance according to the environmental conditions. In the end, we expect that this facility helps us, on one hand to model the behavior of a given technology in a zone where a characterization tool is not available, and on other hand to choose the suitable technology for a given climate. For example, our first results show that the HIT modules give the highest yields in Burkina Faso, a hot environment.

31st European Photovoltaic Solar Energy Conference and Exhibition; 2534-2537, Apollon Solar’s NICE (New Industrial Solar Cell Encapsulation) module technology has been developed among other objectives to provide a long term stable encapsulation for solar cells against environmental impact, such as heat, humidity, UV exposure and mechanical stress. Standard state of the art modules that feature EVA (Ethylene vinyl acetate) encapsulation and a polymer backsheet often show degradation modes after long-term outdoor exposure or accelerated laboratory degradation tests according to the IEC Standard 61215 for module certification, such as the Damp heat test (exposure to 85°C and 85% rH during 1000 hours), or the UV preconditioning test. The NICE module technology overcomes these degradation modes in that it has a glass sheet on the rear instead of a polymer foil and no lamination by polymer materials such as EVA. Instead the module volume is filled by a neutral gas and the environmental protection provided by an edge seal composed of a 10mm wide polyisobuthylene (PIB) ribbon and a secondary silicone based sealing. In this work results from a 9000 hour Damp heat test (9x the requirements of the IEC Standard) on a NICE test module with heterojunction solar cells, carried out by CEA-INES, will be shown. During 9000 hours module power and fill factor have not shown any serious degradation, fluctuations of both parameters within a margin of -2.0% to +2.0% have been observed, some of which can be attributed to test conditions (recalibration of flash tester). Also shown are results from an outdoor installation of industrial size NICE modules on the rooftop of CEA-INES after 3-year exposure. Over this period the module power degradation including Light Induced Degradation (the modules were made from p-type multi-c Silicon solar cells) was in average from 0.4%/y to 0.5%/y.

28th European Photovoltaic Solar Energy Conference and Exhibition; 2935-2938, Usual software and Meteo datasets do not predict with a high accuracy the energy yield of a given photovoltaic module technology at a given site. Then it is not possible to choose clearly between several module types for a specific site nor to decide which site is the better for a given module type. For this reason CEA developed in 2007 the MotherPV method to determine with a high accuracy the productivity of photovoltaic modules. Since 2013, CEA characterizes the modules indoors within a few hours with a slightly adapted procedure described in the part one of the IEC 61853 standard, the standard under development about photovoltaic module energy rating. Regarding Meteo datasets, named Photovoltaic Potential datasets in the MotherPV method, CEA improved its measurement procedure in a common work with the French Radiometric Centre of the World Meteorological Organization. Now, the MotherPV energy rating of modules in summarized in two final Module Performance Panels, one panel for power rating and one panel for energy production. The article describes presents the two panels and the procedures to fill them. The procedure for the Meteo datasets measurement and some of the measured datasets could be included as an alternative in the IEC 61853 standard.

27th European Photovoltaic Solar Energy Conference and Exhibition; 3302-3305, PV modules of identical power do not produce the same energy. Cause is the different sensivity of each technology on temperature, solar spectrum, incident angle, and overall value of the solar irradiance. However, system installers need information in order to choose the best module technology. A simple method has been developed to compute the energy production of PV modules specific to any site. This method is being transferred to CERTISOLIS, which, beside the standard measurements required for module certification, will also be able to offer their clients a prediction of module productivity. This method is applied to commercial sample modules. The irradiance effect and the temperature effect are clearly separated, and the overall productivity of these modules is ranked. For two sample modules, a difference of 5% has been found in yearly energy productivity.

27th European Photovoltaic Solar Energy Conference and Exhibition; 3219-3224, The lifetime energy production of photovoltaic modules depends on their aging behaviour. Aim of the subproject 5 of the EU-PERFORMANCE project is the identification and modelling of long term aging mechanisms. For this purpose, eight different PV module technologies are exposed outdoors at the Solar Outdoor Measurement Platform in Cadarache (South of France) since August 2008. This paper shows the power variations of four PV technologies over 3.85 years (p-Si: -1.1%, CIGS: -7.5%, a-Si: -9.6% and CdTe: -10%) and describes how to link the observed power variations and the ones of the equivalent circuit parameters determined with the Variable Illumination Measurements (VIM). VIM is a simple tool revealing rich information about PV modules. This allowed for a clear separation of the aging of technological key issues determining the performance of the modules: the rectifying capacity, the second diode, the contact resistance, and ohmic leakage currents. The CdTe module shows a degradation of the junction diode parameters indicating an ageing of the active material itself, and a heavy increase of leakage currents. The a-Si module has a problem with the contacts resulting in a high and unstable series resistance. This module and the CIGS module present an initial degradation of the second diode meaning an increase of the leakage currents. The parameters of the p-Si module are almost stable.

26th European Photovoltaic Solar Energy Conference and Exhibition; 3491-3494, This work focuses on the performance analysis of polycrystalline silicon modules which have spent almost two years at La Réunion Island, France, close to Madagascar, compared to modules taken from the same series and exposed outdoor at the National Institute for Solar Energy (INES, Chambéry, France) under continental climate. In this paper, methods used during this work will be described. Based on the two-diode model, comparison of the electrical equivalent circuit parameters will be realized between the tropical and continental exposed modules. Tropical exposed modules showed power degradation of around 10% in 18 months, even if they successfully passed the IEC 61215 certification test and were guaranteed to produce 90% of their initial power for at least ten years. Degradation of EEC parameters is more severe for modules exposed in the tropics than on the continent.

24th European Photovoltaic Solar Energy Conference, 21-25 September 2009, Hamburg, Germany; 4076-4079, The rapid growth of photovoltaic production connected to the network will lead in the coming years to a high penetration rate of this intermittent energy in some distribution networks, especially islands. It is the intermittent and random nature of this type of production which is very demanding for the grid. It is therefore important to accurately predict the global photovoltaic production in a given territory, which can be considered in the planning of the network operator. It is in this context that we have developed a forecasting tool based on physical models and weather forecasts. This tool automatically retrieves weather forecasts, and then refines it in time and space. Taking into account the main features of the plant (location, power, orientation, tilt, ...), the algorithm then calculates the PV production at all times. A second tool performs learning function in order to improve, day by day, the accuracy of forecasting. Our prediction system has been tested during one year on two locations: one in the French Alps and another in the south of France in a very sunny place. The mean absolute error, calculated on an half-hour basis, is less than 10%.

24th European Photovoltaic Solar Energy Conference, 21-25 September 2009, Hamburg, Germany; 3490-3493, The lifetime energy production of photovoltaic modules depends on their aging behaviour. Aim of the subproject 5 of the EU-PERFORMANCE project is the identification and modelling of long term aging mechanisms. For this purpose, eight different PV module technologies are exposed outdoor at the Solar Outdoor Measurement Platform in Cadarache (South of France). The problem is to clearly identify and determine aging effects. Due to the absence of reference cells for thin film technologies, aging of module power is hard to identify. Furthermore, fill factor or efficiency data mix up different aging processes going on in the module. However, module developers do need to know which aging processes limit the lifetime and the performance of the modules. It is therefore proposed to perform measurements which directly access the parameters of the equivalent circuit, and to monitor in-situ the aging of each parameter. This paper demonstrates how this can be done with Variable Illumination Measurements (VIM). The VIM-method is a simple tool revealing rich information about PV modules. This allowed for a clear separation of the aging of five technological key issues determining the performance of the modules: the rectifying capacity, the second diode, the recombination in the i-layer for amorphous silicon modules, the series and parallel resistances.

24th European Photovoltaic Solar Energy Conference, 21-25 September 2009, Hamburg, Germany; 3305-3309, INES/CEA has developed an accurate method, the MotherPV method, for the prediction of the performance of modules for any well known climate. The MotherPV method uses a short campaign of measurements in outdoor conditions to determine 2 module coefficients. The irradiance coefficient at 25 °C expresses the non proportionality of the power of a module as a function of its short circuit current. The irradiance coefficient value at Standard Test Conditions is 1 and is different from 1 at other irradiance levels (the temperature coefficient, depending on the irradiance level, expresses the linearity of the power as a function of the module temperature, at a given irradiance level). In the literature, several models exist to express the irradiance coefficient as a function of the irradiance. The present work compares the accuracy of the different existing models and of a new INES/CEA model, for six module technologies characterised at INES/CEA with the MotherPV method. For crystalline silicon modules, existing models give an excellent representation of the irradiance coefficient The new model gives the best accuracy for all the modules (better than 1% at a 95% confidence level), especially for thin film modules. This new model can be used in the MotherPV method or in any existing method to predict or monitor very accurately the energy production of photovoltaic modules and systems

24th European Photovoltaic Solar Energy Conference, 21-25 September 2009, Hamburg, Germany; 3451-3455, INES/CEA has developed the MotherPV method (Meteorogical, Optical and Thermal Histories for the Energy Rating of PhotoVoltaics) allowing the monitoring of the performance of photovoltaic modules and systems: to determine the power of the module at any irradiance and temperature levels, two coefficients are used in this method: the irradiance coefficient at 25 °C and the temperature coefficient. In this work, the MotherPV method has been applied for the first time to CIS modules in three European outdoor PV laboratories involved in the Performance Project: the National Institute for Solar Energy (INES/CEA - France), the Wroclaw University of Technology (WrUT - Poland) and the Centre for Solar and Hydraulic Energy (ZSW – Germany). An improvement of the method has been developed to take into account the stabilization period of CIS. The values of the irradiance coefficient and of the temperature coefficient have been compared for four CIS modules of different types. The behaviour of the studied CIS modules is different from the behaviour of other module technologies, even if one can observe discrepancies between CIS modules.

23rd European Photovoltaic Solar Energy Conference and Exhibition, 1-5 September 2008, Valencia, Spain; 2841-2845, PV-modules of identical nominal power do not perform equal. This paper examines the irradiance dependence of module performance for wafer based and thin film silicon modules. Technology factors limiting the performance are identified. For this purpose, data from variable illumination measurements (VIM) of the I/V curve are analysed using a modified two diode model. The VIM-method is a simple tool revealing rich information about PV modules. This allowed for a clear separation of five technological key issues determining the performance of the modules: the rectifying capacity, the second diode, the recombination in the i-layer for amorphous silicon modules, the series and parallel resistances.