Carbon nanotube net as a conductive and transparent film for solar energy conversion

Vertically aligned silicon nanowires arrays have been grown through a metal-assisted chemical etching method, giving a heavily absorbing surface. Over this surface, a transparent and conductive net of carbon nanotubes has been formed by chemical vapour deposition. The optical characterisation of the net has been performed by the study of its hemispherical reflectance, and the electrical properties have been obtained by four-point probe method. A high transmittance of the net (over 99%) in the 300-900 nm range is reported. Also, a good sheet resistance value has been obtained (around 3 kΩ/□) for such a thin carbon nanotube netThis work was supported by MINECO research Project ENE2014-57977-C2-1-

Low-cost irradiance sensors for irradiation assessments inside tree canopies.

The solar irradiation that a crop receives is directly related to the physical and biological processes that affect the crop. However, the assessment of solar irradiation poses certain problems when it must be measured through fruit inside the canopy of a tree. In such cases, it is necessary to check many test points, which usually requires an expensive data acquisition system. The use of conventional irradiance sensors increases the cost of the experiment, making them unsuitable. Nevertheless, it is still possible to perform a precise irradiance test with a reduced price by using low-cost sensors based on the photovoltaic effect. The aim of this work is to develop a low-cost sensor that permits the measurement of the irradiance inside the tree canopy. Two different technologies of solar cells were analyzed for their use in the measurement of solar irradiation levels inside tree canopies. Two data acquisition system setups were also tested and compared. Experiments were performed in Ademuz (Valencia, Spain) in September 2011 and September 2012 to check the validity of low-cost sensors based on solar cells and their associated data acquisition systems. The observed difference between solar irradiation at high and low positions was of 18.5% ± 2.58% at a 95% confidence interval. Large differences were observed between the operations of the two tested sensors. In the case of a-Si cells based mini-modules, an effect of partial shadowing was detected due to the larger size of the devices, the use of individual c-Si cells is recommended over a-Si cells based mini-modules

Influencia de diferentes temperaturas de sustrato y concentraciones de ácido indolbutírico en el esquejado de Coriaria myrtifolia

Se estudia Coriaria myrtifolia Linn., especie autóctona de interés ecológico (fijadora de N), medicinal (coriamirtina en los frutos) y ornamental (uso en reforestación de zonas pobres en N y como verde de complemento en floristería y en jardinería). Se pretende mejorar su multiplicación por esqueje, mediante uso de ácido indolbutírico (AIB) como hormona favorecedora del enraizamiento que ya ha mostrado su efectividad en numerosas especies, entre ellas Nerium oleander (Kose, 2000), también autóctona del Mediterráneo.Trabajo financiado por los proyectos: MCYT-FEDER AGL2001-2249-C03-01 y AGL2000-052 CICYT-FEDER. Expresamos nuestro agradecimiento a la Dir. Gral. de Investigación y Transf. Tecnológica de la Consejería de Agricultura, Agua y Medio Ambiente de la Región de Murcia por su colaboración para la ejecución de este trabaj

Silicon PV module customization using laser technology for new BIPV applications

It is well known that lasers have helped to increase efficiency and to reduce production costs in the photovoltaic (PV) sector in the last two decades, appearing in most cases as the ideal tool to solve some of the critical bottlenecks of production both in thin film (TF) and crystalline silicon (c-Si) technologies. The accumulated experience in these fields has brought as a consequence the possibility of using laser technology to produce new Building Integrated Photovoltaics (BIPV) products with a high degree of customization. However, to produce efficiently these personalized products it is necessary the development of optimized laser processes able to transform standard products in customized items oriented to the BIPV market. In particular, the production of semitransparencies and/or freeform geometries in TF a-Si modules and standard c-Si modules is an application of great interest in this market. In this work we present results of customization of both TF a-Si modules and standard monocrystalline (m-Si) and policrystalline silicon (pc-Si) modules using laser ablation and laser cutting processes. A discussion about the laser processes parameterization to guarantee the functionality of the device is included. Finally some examples of final devices are presented with a full discussion of the process approach used in their fabrication

Caracterización de radiómetros absolutos de cavidad como patrones primarios de irradiancia solar

CIES2020 - XVII Congresso Ibérico e XIII Congresso Ibero-americano de Energia SolarRESUMEN: Los radiómetros absolutos de cavidad (ACR) son los instrumentos de mayor nivel metrológico para la medida de la irradiancia solar directa (DNI), que trabajan según el principio de sustitución eléctrica. Para asegurar su trazabilidad, se comparan (cada 5 años) contra el grupo de patrones WSG que materializan la referencia radiométrica mundial WRR en el PMOD/WRC (Davos, Suiza). Sin embargo, también pueden caracterizarse de forma absoluta mediante la calibración, el modelado y cálculo numérico de todos sus componentes, en base a una ecuación o función de medida, para obtener su incertidumbre total de medida. Este artículo describe distintas tareas realizadas en la caracterización de dos ACR y los resultados preliminares encontrados. En el caso del Eppley AHF, se han calibrado las magnitudes eléctricas y el área de la apertura de precisión, se han determinado la absortancia y el factor de no-equivalencia, así como la dependencia de la corriente en el circuito calefactor de la cavidad con la temperatura. Con estos resultados se esperan alcanzar los objetivos de una incertidumbre inferior a 1000 ppm en DNI y la trazabilidad directa al SI.ABSTRACT: Absolute Cavity Radiometers (ACR) are the instruments, working under the principle of electrical substitution, of the highest metrological level for measuring Direct Normal Irradiance (DNI). To ensure their traceability, they are compared every 5 years in PMOD/WRC (Davos, Switzerland) to the group of standards WSG realizing the World Radiometeric Reference WRR. However, they can also be characterized in an absolute way through the calibration, modelling and numeric simulation of all their components, based on a measurement function, and obtaining their total measurement uncertainty. This paper describes different labors carried out in the characterization of two ACRs and the preliminary results obtained. In the case of the Eppley Labs’ AHF radiometer, the electrical magnitudes and the precision aperture area have been calibrated, effective absorptance and non-equivalence factor have been determined, as well as the dependence on temperature of the electrical current in the heater of the ACR cavity. With these results, the objectives of an uncertainty below 1000 ppm in DNI and the direct traceability to SI can be achieved.info:eu-repo/semantics/publishedVersio

Interlaboratory comparison of methodologies for measuring the angle of incidence dependence of solar cells

The aim of this work is to compare angle of incidence (AOI) measurement setups for solar cells between laboratories with such capability. For the first time, we compare relative light transmission measurements among eight laboratories, whose measurement techniques include indoor and outdoor methods. We present the relative transmission measurements on three 156 mm x 156 mm crystalline-Si (c-Si) samples with different surface textures. The measurements are compared using the expanded uncertainties provided by each laboratory. Five of the eight labs showed an agreement better than ±2% to the weighted mean between AOIs from -75° to 70°. At AOIs of ±80° and ±85°, the same five labs showed a worst case deviation to the weighted mean of -3% to 5% and 0% to 18%, respectively. When measurement uncertainty is considered, the results show that measurements at the highest incidence angle of ±85° are problematic, as measurements from four out of the six labs reporting uncertainty were found non-comparable within their stated uncertainties. At 85° AOI a high to low range of up to 75% was observed between all eight laboratories

A European proficiency test on thin film tandem photovoltaic devices

A round robin proficiency test RR PT on thin film multi junction MJ photovoltaic PV cells was run between 13 laboratories within the European project CHEETAH. Five encapsulated PV cells were circulated to participants for being tested at Standard Test Conditions STC . Three cells were a Si amp; 956;c Si tandem PV devices, each of which had a different short circuit current ratio between the top junction and the bottom one; the remaining two cells were single junction PV devices made with material representative of the individual junctions in the MJ cells. The RR PT s main purpose was to assess the capability of the participating laboratories, in terms of employed facilities and procedures, to test MJ PV devices. Therefore, participant

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Pabellón Administrativo. Universidad de Huelva

Uncertainty in the Calibration Transfer of Solar Irradiance Scale: From Absolute Cavity Radiometers to Standard Pyrheliometers

In this work, the method for calculation of uncertainty of pyrheliometers’ responsivity during their outdoor calibration process in the laboratory is exposed. It is applied first for calibration of standard pyrheliometers by comparison to cavity radiometers, and after for calibration of an end-user pyrheliometer against that standard pyrheliometer. The dissemination of the WRR irradiance scale is illustrated in practice and the increasing uncertainty in the traceability chain is quantified. The way of getting traceability to both WRR scale and to SI units in the current situation, where the shift between these radiometric scales is pending to be solved, is also explained. However, the impact of this gap between scales seems to be more important for calibrations of reference Class A pyrheliometers than in the final determination of DNI irradiance, because in this case, the cumulative uncertainty is large enough as to not significantly be affected for the difference. The way to take into account different correction terms in the measurement model function, and how to compute the corresponding uncertainty, is explained too. The influence of temperature of some pyrheliometers during calibration process and the potential impact on the DNI irradiance calculated with these instruments is exemplified