Browsing by Author "Zubillaga, Oihana"
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Item Broadband antireflective coating stack based on mesoporous silica by acid-catalyzed sol-gel method for concentrated photovoltaic application(2018-11) Agustín-Sáenz, Cecilia; Sánchez-García, José Ángel; Machado, Maider; Brizuela, Marta; Zubillaga, Oihana; Tercjak, Agnieszka; Tecnalia Research & Innovation; VALORIZACIÓN DE RESIDUOS; INGENIERÍA DE SUPERFICIES; SISTEMAS FOTOVOLTAICOSSilica multi-layer stacks have been designed with the aim to provide broadband antireflective (AR) properties for glass components in concentrated photovoltaic (CPV) application. Silica porous coatings were grown by combining acid-catalyzed sol-gel route and evaporation induced self-assembly (EISA) method with four types of organic/inorganic systems. Sols were prepared using tetraethylorthosilicate (TEOS) as inorganic precursor assembled with two di-block copolymers, one tri-block copolymer and one cationic surfactant as organic templates. Optical properties were characterized by ellipsometry and spectrophotometry while the material structure was analyzed by environmental ellipsometric porosimetry (EEP) and atomic force microscopy (AFM). The concentration of inorganic and organic phases was optimized and a broadband AR bi-layer stack was obtained providing a 7.2% (under the reference AM1.5 solar spectral irradiance) increase in transmittance over bare glass in the wavelength range 300–2000 nm when coated on both sides.Item Changes of solar cell parameters during damp-heat exposure(2016-10-01) Zhu, Jiang; Koehl, Michael; Hoffmann, Stephan; Berger, Karl Anton; Zamini, Shokufeh; Bennett, Ian; Gerritsen, Eric; Malbranche, Philippe; Pugliatti, Paola; Di Stefano, Agnese; Aleo, Francesco; Bertani, Dario; Paletta, Fabrizio; Roca, Francesco; Graditi, Giorgio; Pellegrino, Michele; Zubillaga, Oihana; Cano, F.J.; Pozza, Alberto; Sample, Tony; Gottschalg, Ralph; Iranzo, F. J.Cano; SISTEMAS FOTOVOLTAICOS; SGThe electrical ageing of photovoltaic modules during extended damp-heat tests at different stress levels is investigated for three types of crystalline silicon photovoltaic modules with different backsheets, encapsulants and cell types. Deploying different stress levels allows determination of an equivalent stress dose function, which is a first step towards a lifetime prediction of devices. The derived humidity dose is used to characterise the degradation of power as well as that of the solar cell's equivalent circuit parameters calculated from measured current–voltage characteristics. An application of this to the samples demonstrates different modes in the degradation and thus enables better understanding of the module's underlying ageing mechanisms. The analysis of changes in the solar cell equivalent circuit parameters identified the primary contributors to the power degradation and distinguished the potential ageing mechanism for each types of module investigated in this paper. © 2016 The Authors. Progress in Photovoltaics: Research and Applications published by John Wiley & Sons Ltd. © 2016 The Authors. Progress in Photovoltaics: Research and Applications published by John Wiley & Sons Ltd.Item Composite material incorporating protective coatings for photovoltaic cell encapsulation(2022-09-15) Yurrita, Naiara; Aizpurua, Jon; Cambarau, Werther; Imbuluzqueta, Gorka; Hernández, Juan M.; Cano, Francisco J.; Huerta, Irene; Rico, Elena; Caño, Teodosio del; Wölper, Sarah; Haacke, Florian; Zubillaga, Oihana; Tecnalia Research & Innovation; SISTEMAS FOTOVOLTAICOS; SGPhotovoltaic modules consisting of one back-contact cell were manufactured by vacuum resin infusion process using glass reinforced epoxy composite as encapsulant where the cells are embedded. Incorporation of three coatings onto the composite surface was studied with the aim to improve the electrical performance stability of the modules under ultraviolet (UV), thermal cycling and damp-heat environmental weathering. Photovoltaic and aging performance were examined through the short-circuit current density values and colour change of the composite. Decrease in the initial photovoltaic performance of the modules was caused by the coating deposition. The highest drop in the initial values was observed for the varnish type coating, showing a decrease of 2.6% in short-circuit current. Regarding the performance stability, the decrease was more pronounced in the damp-heat test, presenting the varnish type coating the minimum loss of 1.4% in short-circuit current and a variation of 87% in b* chromatic parameter after 1000 h exposure at 85 °C and 85% relative humidity. The study concluded that the protective coating should be selected to provide the composite modules with an optimal trade-off between the initial electrical performance and the desired stability, with further research work targeted to improve moisture barrier properties.Item Composite material with enhanced ultraviolet performance stability for photovoltaic modules(2019-09-15) Imbuluzqueta, Gorka; Yurrita, Naiara; Aizpurua, Jon; Cano, Francisco J.; Zubillaga, Oihana; SISTEMAS FOTOVOLTAICOS; SGThe present work aims encapsulating photovoltaic cells in glass reinforced epoxy composite by vacuum resin infusion, incorporating additives directed to enhance the performance stability of the manufactured photovoltaic modules under ultraviolet (UV) exposure. UV absorber (UVA) and hindered amine light stabilizer (HALS) additives were incorporated in the resin system in different content. Photovoltaic performance and stability under UV radiation exposure were studied through external quantum efficiency (EQE) spectra, chromatic coordinates and short-circuit current values. Decrease in current values and increase in yellowness were observed in the presence of UVA and HALS. However, an enhanced performance stability was observed when additives are incorporated, improving the stability when increasing the additive amount. The most stable module, with cells embedded in 2% additive containing composite, showed a 2.7% short-circuit current loss after UV aging exposure.Item Development of a resistivity standard for polymeric materials used in photovoltaic modules(SPIE, 2015) Kempe, Michael D.; Miller, David C.; Nobles, Dylan L.; Sakurai, Keiichiro; Tucker, John; Bokria, Jayesh G.; Shioda, Tsuyoshi; Nanjundiah, Kumar; Yoshihara, Toshio; Birchmier, Jeff; Zubillaga, Oihana; Wohlgemuth, John H.; Dhere, Neelkanth G.; Jones-Albertus, Rebecca; Wohlgemuth, John H.; SISTEMAS FOTOVOLTAICOSPhotovoltaic (PV) modules, operate at high voltages and elevated temperatures, and are known to degrade because of leakage current to ground. Related degradation processes may include: electric/ionic corrosion, electrochemical deposition, electromigration, and/or charge build-up in thin layers. The use of polymeric materials with a high resistivity is known to reduce the rate of potential induced degradation processes. Because of this, PV materials suppliers are placing increased importance on the encapsulant bulk resistivity, but there is no universally accepted method for making this measurement. The development of a resistivity test standard is described in this paper. We have performed a number of exploratory and round-robin tests to establish a representative and reproducible method for determining the bulk resistivity of polymeric materials, including encapsulation, backsheet, edge seals, and adhesives. The duration of measurement has been shown to greatly affect the results, e.g., an increase as great as 100X was seen for different measurement times. The standard has been developed using measurements alternating between an on and off voltage state with a weighted averaging function and cycle times of an hour.Item Hydrophobic and spectrally broadband antireflective methyl-silylated silica coatings with high performance stability for concentrated solar applications(2019-09-15) Agustín-Sáenz, Cecilia; Machado, Maider; Zubillaga, Oihana; Tercjak, Agnieszka; Tecnalia Research & Innovation; VALORIZACIÓN DE RESIDUOS; SISTEMAS FOTOVOLTAICOSAn efficient and environment-friendly process, consisting of acid-catalyzed sol-gel process combined with evaporation induced self-assembly, was conducted to build antireflective (AR) layer stacks for concentrated solar applications. Considering the external factors that may alter the optical properties of the system when operating outdoors, such as soiling, harsh climate conditions and alkali ions diffusion from glass, several stack configurations were proposed. Particularly, the effect of a methyl-silylating post-treatment, the presence of the inner layer and the optimization of sintering temperature have been devised in order to minimize soiling adherence and alkali diffusion from the glass substrate and to assure the required robustness to comply with the durability requirements. The assessment consisted of (i) an analysis of the optical transmittance, reflectance and refractive index and (ii) hydrophobicity and effect of water absorption on the external porous coatings in relation to the results of accelerated aging tests following photovoltaics standards. The main goal was to achieve the most rational design, based on a proper trade-off between cost efficiency, processability, optical properties and reliability during real life operation.Item Photovoltaic modules encapsulated in composite material modified with ultraviolet additives(2021-09-15) Yurrita, Naiara; Aizpurua, Jon; Cambarau, Werther; Imbuluzqueta, Gorka; Hernández, Juan María; Cano, Francisco J.; Zubillaga, Oihana; Tecnalia Research & Innovation; SISTEMAS FOTOVOLTAICOS; SGPhotovoltaic modules were manufactured by vacuum resin infusion process using glass reinforced epoxy composite as encapsulant where the cells are embedded. Incorporation of ultraviolet absorber (UVA) and hindered amine light stabilizer (HALS) additives to the epoxy resin was studied, given their potential to enhance the performance stability of the modules under ultraviolet (UV) radiation exposure. Photovoltaic and aging performance were examined through the evolution of external quantum efficiency (EQE) spectra, short-circuit current values and colour change. Decrease in the initial photovoltaic performance of the modules was observed, as evidenced in the short-circuit losses when additives are incorporated. Regarding the performance stability, increasing the content of both, UVA and HALS, leaded to improved results with lower short-circuit current loss and yellowness observed due to UV radiation. The most stable module, with cells embedded in 1% UVA and 1% HALS containing composite, showed a 2.8% short-circuit current loss after an UV exposure of 15.4 KWh/m2. UV protection enhancement was obtained in trade-off with initial photovoltaic performance, which should be considered when defining the additives and the amount to be used.Item Round robin performance testing of organic photovoltaic devices(2014-03) Gevorgyan, Suren A.; Zubillaga, Oihana; Vega de Seoane, José María; Machado, Maider; Parlak, Elif Alturk; Tore, Nesrin; Voroshazi, Eszter; Aernouts, Tom; Müllejans, Harald; Bardizza, Giorgio; Taylor, Nigel; Verhees, Wiljan; Kroon, Jan M.; Morvillo, Pasquale; Minarini, Carla; Roca, Francesco; Castro, Fernando A.; Cros, Stéphane; Lechêne, Balthazar; Trigo, Juan F.; Guillén, Cecilia; Herrero, José; Zimmermann, Birger; Sapkota, Subarna Babu; Veit, Clemens; Würfel, Uli; Tuladhar, Pabitra S.; Durrant, James R.; Winter, Stefan; Rousu, Sanna; Välimäki, Marja; Hinrichs, Volker; Cowan, Sarah R.; Olson, Dana C.; Sommer-Larsen, Peter; Krebs, Frederik C.; SISTEMAS FOTOVOLTAICOS; Tecnalia Research & InnovationThis study addresses the issue of poor intercomparability of measurements of organic photovoltaic (OPV) devices among different laboratories. We present a round robin performance testing of novel OPV devices among 16 laboratories, organized within the framework of European Research Infrastructure Project (SOPHIA) and European Energy Research Alliance (EERA). Three types of OPVs with different structures, dimensions and encapsulations are studied and compared with reference Si solar cells certified by accredited laboratories. The agreement of the measurements of these among different laboratories is analyzed by focusing on testing procedures, testing equipment and sample designs. A number of deviations and pitfalls are revealed and based on the analyses, a set of recommendations are suggested for improving the agreement among the measurements of such OPV technologies.