Early degradation of PV modules and guaranty conditions

CIEMAT PVLabDER has largely increased its demand on testing and characterizing PV plants, according to the fast growth of PV installed capacity in Spain. One of the topics in which manufacturers, promoters, and owners of the plants are more interested in, is the possible degradation of PV modules and its relationship to guarantee contracts, as it is related to subsidies. This paper presents some findings in campaigns of PV plants evaluation carried out during last years. This evaluation usually consists of visual inspection, I-V curve measurement in the fields (the whole plant or selected areas), thermal evaluation by IR imaging, and, in some cases, measurement of the I-V characteristic and thermal behaviour of selected modules in the plant, chosen by the laboratory. It must be noticed that new defects that grow when the module is into operation may appear in modules initially free of them (named as hidden manufacturing defects). Usually some of these hidden defects that only appear in normal operation are not detected in reliability tests (EN61215 or EN 61646) [4][5] due to the different operational conditions of the module in the standard tests and in the field (serial-parallel connection of many PV modules, power inverter influence, over voltage on wires, etc.

Early degradation of PV modules and guaranty conditions

CIEMAT PVLabDER has largely increased its demand on testing and characterizing PV plants, according to the fast growth of PV installed capacity in Spain. One of the topics in which manufacturers, promoters, and owners of the plants are more interested in, is the possible degradation of PV modules and its relationship to guarantee contracts, as it is related to subsidies. This paper presents some findings in campaigns of PV plants evaluation carried out during last years. This evaluation usually consists of visual inspection, I-V curve measurement in the fields (the whole plant or selected areas), thermal evaluation by IR imaging, and, in some cases, measurement of the I-V characteristic and thermal behaviour of selected modules in the plant, chosen by the laboratory. It must be noticed that new defects that grow when the module is into operation may appear in modules initially free of them (named as hidden manufacturing defects). Usually some of these hidden defects that only appear in normal operation are not detected in reliability tests (EN61215 or EN 61646) [4][5] due to the different operational conditions of the module in the standard tests and in the field (serial-parallel connection of many PV modules, power inverter influence, over voltage on wires, etc.

Influence of initial power stabilization over crystalline-Si photovoltaic modules maximum power

Measurements that suppliers offer in specification sheets are not always close to the actual power measured in independent laboratories such as CIEMAT. Independent measurements tend to be lower than those printed on the label sometimes even lower than the allowed tolerance indicated by the manufacturer on the same label. Furthermore, a potentially significant power reduction has been reported when Standard EN50380 (which requires photovoltaic (PV) modules to be exposed to more than 20 kWh/m2 of sunlight prior to taking the measurements that appear on the label) is followed. This is the initial power stabilization and this work studies the power stabilization that tends to appear in crystalline PV modules. Crystalline PV modules usually decrease in power around 1%, but decreases >4% have also been reported. These power losses are only detected after the mentioned power stabilizatio

Analysis of air mass dependence of three photovoltaic arrays

The solar spectrum, which is also could be described by air mass factor, has a significant relationship with the performance of photovoltaic modules. The air mass dependence has been investigated by a theoretical method as well as an actual case of three different photovoltaic arrays: polycrystalline silicon, amorphous silicon and cadmium telluride, at the EUIT Agrícola-UPM (Madrid, Spain, 40.4426oN, 3.7295oW). The calculating results show that: AM dependence of poly-Si array is positive because an elevating AM-value indicates a red shift and poly-Si module is more red sensitive; On the contrary, as a-Si module and CdTe module are more blue sensitive, their AM dependences are negative. Furthermore, the outdoor AM dependences of three arrays are corresponding to the calculating results although the thermal annealing effect could be superimposed on spectral effect in the case of a-Si. Keywords: PV system, spectral response, polycrystalline silicon, a-Si, CdT

Evaluación del uso de paneles solares como elemento de sombreo en invernaderos

El objetivo principal de este trabajo experimental, es evaluar el uso de paneles solares como opción de elemento de sombreo en viveros, tanto de gran escala como de pequeña superficie. Esta opción podría elegirse tanto en el caso de no disponer de red de suministro eléctrico cercano así como en el caso de preferir no depender de una fuente de energía eléctrica exterior. Como hecho novedoso, se ha elegido paneles solares flexibles de capa fina y poco peso, que serían situados en la cubierta del invernadero. Dicha elección permite que los paneles se adapten a la forma de la cubierta, sea cual fuere

Thim Films Modules Characterization Under Standard Test Conditions

Photovoltaic modules based on the relatively new thin film technology are gaining importance in the photovoltaic market. Some of these modules are made of silicon, consisting of layers of amorphous silicon or microcrystalline silicon. Other thin film PV modules are made of CIS, Cadmium Telluride (CdTe) or less frequently organic compounds. The materials used in thin film technologies pose problems in terms of measuring how much power is generated under standard test conditions (STC). This is due to the fact that the modules´ power rates could vary depending both on the amount of time they have been exposed to the sun and on their history of sunlight exposure. So it is necessary to know the previous periods of sunlight exposure in order to know the current state of the module. It is necessary to determine an easily accomplishable testing method that ensures the repeatability of the measurements of the power generated. This is essential because in order to have a reliable sample of the PV module population of a large PV plant, a huge number of modules must be measured. This paper shows different tests performed on different commercial thin film PV modules in order to find the best way to obtain measurements. A correlation was tested between sun exposure and power measured. A method for obtaining indoor measurements of these technologies that takes periods of sunlight exposure into account is proposed. Additionally, temperature and irradiance coefficients were also determined for different technologies in order to obtain accurate measurements

Practical issues for testing thin film PV modules at standard test conditions.

Thin film photovoltaic (TF) modules have gained importance in the photovoltaic (PV) market. New PV plants increasingly use TF technologies. In order to have a reliable sample of a PV module population, a huge number of modules must be measured. There is a big variety of materials used in TF technology. Some of these modules are made of amorphous or microcrystalline silicon. Other are made of CIS or CdTe. Not all these materials respond the same under standard test conditions (STC) of power measurement. Power rates of the modules may vary depending on both the extent and the history of sunlight exposure. Thus, it is necessary a testing method adapted to each TF technology. This test must guarantee repeatability of measurements of generated power. This paper shows responses of different commercial TF PV modules to sunlight exposure. Several test procedures were performed in order to find the best methodology to obtain measurements of TF PV modules at STC in the easiest way. A methodology for indoor measurements adapted to these technologies is described

Electrochemical and bioelectrocatalytical properties of novel block-copolymers containing interacting ferrocenyl units

The electrochemical characterization of three different polystyrene-b-polybutadiene block copolymers functionalized with ferrocenyl units electronically communicated, PSm-PBn(HSiMeFc2)p where m=615, n=53, p=39 (1), m=375, n=92, p=76 (2) and m=455, n=204, p=170 (3), has been carried out both in solution and electrochemically deposited onto platinum electrodes. The bioelectrocatalytical properties of electrodes modified with the polymers in the nicotinamide dinucleotide (NADH) and glucose oxidase (GOx) oxidations have been investigated as a function of the constitution and structure of the polymers. The analytical properties of electrodes modified with these polymers as sensors of NADH and GOx are described. In addition, an amperometric biosensor for glucose, prepared by electrostatic immobilization of glucose oxidase onto a platinum electrode modified with one of the ferrocenyl block copolymers as an example, has been developed. The results confirm that electrodes modified with the examined copolymers act as efficient redox mediators for the electrocatalytic oxidation of both reduced nicotinamide dinucleotide cofactor and glucose oxidase. The reaction with NADH proceeds via formation of a charge-transfer intermediate before yielding the reaction products. This is a novel example of electrodes modified with ferrocene derivatives that can be applied to the determination of NADH without the use of diaphorase. The redox copolymers co-immobilized with glucose-oxidase have been successfully used as amperometric biosensors for glucose determinations. As expected these compounds allow using lower working potentials. The sensitivities and detection limits obtained are comparable or even better than those of other ferrocene-modified polymers mediator electrodes

Transcriptomic Profiles of Senegalese Sole Infected With Nervous Necrosis Virus Reassortants Presenting Different Degree of Virulence

Betanodaviruses [nervous necrosis virus (NNV)] are the causative agent of the viral encephalopathy and retinopathy, a disease that affects cultured Senegalese sole (Solea senegalensis). NNV reassortants, combining genomic segments from redspotted grouper nervous necrosis virus (RGNNV) and striped jack nervous necrosis virus (SJNNV) genotypes, have been previously isolated from several fish species. The wild-type reassortant wSs160.03, isolated from Senegalese sole, has been proven to be more virulent to sole than the parental genotypes (RGNNV and SJNNV), causing 100% mortality. Mutations at amino acids 247 (serine to alanine) and 270 (serine to asparagine) in the wSs160.03 capsid protein have allowed us to obtain a mutant reassortant (rSs160.03247+270), which provokes a 40% mortality decrease. In this study, the RNA-Seq technology has been used to comparatively analyze Senegalese sole transcriptomes in two organs (head kidney and eye/brain) after infection with wild-type and mutant strains. A total of 633 genes were differentially expressed (DEGs) in animals infected with the wild-type isolate (with higher virulence), whereas 393 genes were differentially expressed in animals infected with the mutant strain (37.9% decrease in the number of DEGs). To study the biological functions of detected DEGs involved in NNV infection, a gene ontology (GO) enrichment analysis was performed. Different GO profiles were obtained in the following subclasses: (i) biological process; (ii) cellular component; and (iii) molecular function, for each viral strain tested. Immune response and proteolysis have been the predominant biological process after the infection with the wild-type isolate, whereas the infection with the mutant strain induces proteolysis in head kidney and inhibition of vasculogenesis in nervous tissue. Regarding the immune response, genes coding for proteins acting as mediators of type I IFN expression (DHX58, IRF3, IRF7) and IFN-stimulated genes (ISG15, Mx, PKR, Gig1, ISG12, IFI44, IFIT-1, to name a few) were upregulated in animals infected with the wild-type isolate, whereas no-differential expression of these genes was observed in samples inoculated with the mutant strain. The different transcriptomic profiles obtained could help to better understand the NNV pathogenesis in Senegalese sole, setting up the importance as virulence determinants of amino acids at positions 247 and 270 within the RNA2 segment

Gilthead seabream (Sparus aurata) Mx proteins show positive and negative synergy in their antiviral activity

Due to their direct antiviral activity, Mx proteins play a main role in the response mediated by the type I interferon against viral infections. The study of the farmed fish gilthead seabream Mx genes is specially interesting, since this species displays an unusually high natural resistance to viral diseases, becoming a potential asymptomatic carrier and/or reservoir for several viruses pathogenic to other fish species. Gilthead seabream has three Mx proteins (Mx1, Mx2 and Mx3) that, separately, display antiviral activity against a wide range of viruses, showing interesting differences in their antiviral specificities. In this work, the possible synergy between the three Mx isoforms has been studied using in vitro systems, consisting of permanently transfected CHSE-214 cells expressing two or the three gilthead seabream Mx proteins. The antiviral activity of these Mx combinations has been tested against the infection by the Infectious Pancreatic Necrosis Virus (IPNV), the Viral Haemorrhagic Septicaemia Virus (VHSV) and the European Sheatfish Virus (ESV) in cells inoculated at 0.1 and 0.01 multiplicity of infection (MOI). The antiviral effect was evaluated by viral titration (TCID50 method). Interestingly, a positive synergistic effect in the antiviral activity against ESV was observed when Mx2 and Mx3 were combined, and this effect was intensified when the three isoforms were present in these cells. In contrast, the presence of more than one Mx isoform interfered with the antiviral activity against IPNV and VHSV showed by the Mx proteins expressed separately. Furthermore, Mx2 combined with Mx3, and the combination of the three Mx proteins exerted a negative synergistic effect against IPNV infection. Specifically, the viral titres were significantly higher in Mx expressing cells than in control cells. In the same way, in Mx1 and Mx2 expressing cells infected with VHSV the viral replication was alsoincreased. These results suggest the interaction between Mx isoforms, in which the expression level of each isoform might be an important factor, and support the idea of finely tuned mechanisms controlling the antiviral activity of Mx proteins. The authors want to thank Dr. C. P. Dopazo (University of Santiago de Compostela, Spain) and Dr. K. Way (CEFAS, Weymouth lab, UK) for supplying the viruses VHSV and ESV, respectively, used in this work.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech