• Energy Research

The spectral distribution of the solar irradiance incident on photovoltaic (PV) modules is a key variable controlling their power production. It is required to properly simulate the production and performance of PV plants based on technologies with different spectral characteristics. Spectroradiometers can only sense the solar spectrum within a wavelength range that is usually too short compared to the actual spectral response of some PV technologies. In this work, a new methodology based on the Simple Model of the Atmospheric Radiative Transfer of Sunshine (SMARTS) spectral code is proposed to extend the spectral range of measured direct irradiance spectra and to increase the spectral resolution of such experimental measurements. Satisfactory results were obtained for both clear and hazy sky conditions at a radiometric station in southern Spain. This approach constitutes the starting point of a general methodology to obtain the instantaneous spectral irradiance incident on the plane of array of PV modules and its temporal variations, while evaluating the magnitude and variability of the abundance of atmospheric constituents with the most impact on surface irradiance, most particularly aerosols and water vapor.

The performance of photovoltaic panels decreases depending on the different factors to which they are subjected daily. One of the phenomena that most affects their energy production is dust deposition. This is particularly acute in desert climates, where the level of solar radiation is extreme. In this work, the effect of dust soiling is examined on the electricity generation of an experimental photovoltaic pilot plant, installed at the Solar Energy Research Center (CIESOL) at the University of Almería. An average reduction of 5% of the power of a photovoltaic plant due to dust contamination has been obtained, this data being used to simulate the economic effect in plants of 9 kWp and 1 and 50 MWp. The economic losses have been calculated, and are capable of being higher than 150,000 €/year in industrial plants of 50 MWp. A cleaning strategy has also been presented, which represents a substantial economic outlay over the years of plant operation.

The optical characterization of different PV modules for integration in buildings (BIPV) is presented in this paper. The investigated PV modules are laminated glasses (PV laminates) suitable for integration in façades and windows. They are made of different PV cell technologies and some of them present a certain transparency degree, making possible to combine daylighting properties with solar control and electrical generation. The approach is based on spectral UV/vis/NIR reflectance and transmittance measurements of the different considered samples, both at normal incidence and as a function of the angle of incidence when it is possible. The European standard protocols are used to determine the luminous and the solar characteristics of each sample, enabling the optical assessment of these PV modules as building elements. The results indicate the good properties of PV laminates in terms of daylighting and solar control capabilities allowing a feasible efficient integration in building façades and windows. The obtained characteristic parameters can be used to simulate the influence in the energy balance of a building of different types of PV modules integrated in façade or window elements. © 2015 Elsevier B.V. All rights reserved.

Particle deposition on the surface of modules in PV systems produces energy output losses with an impact that highly depends on the meteorological and climatic conditions. This work presents the characterization of soiling losses for a suburban forest area in Madrid focused on rooftop PV systems. The soiling loss measured in the testing system can reach around 6%/day for a tilt angle of 8° during summer. Models assessment is also presented and analyzed here using two available soiling models from the well-known pvlib package. The use of the models is not straightforward and some assumptions and recommendations are also presented in this work to produce the best predictions. The applicability of physical models to suburban areas, particularly in large cities in Europe, is remarked by the availability of air quality monitoring ground stations. These results will enhance future studies on the potential impact of soiling in European cities that will help to the distributed PV systems growth and penetration. The authors would like to thank the PVCastSOIL Project (ENE2017-469 83790-C3-1, 2 and 3), which is funded by the Ministerio de Economía y Competitividad (MINECO), and co-financed by the European Regional Development Fund. The authors also acknowledge ANID/FONDAP/15110019 “Solar Energy Research Center” SERC-Chile; the Chilean Economic Development Agency (CORFO) with contract No 17PTECES-75830 under the framework of the project “AtaMoS TeC”; the generous financial support provided by GORE-Antofagasta, Chile, Project FIC-R Antofagasta 2017 BIP code 30488824-0. Ingeniería Eléctrica y Térmica, de Diseño y Proyectos

Atmospheric factors, such as clouds, wind, dust, or aerosols, play an important role in the power generation of photovoltaic (PV) plants. Among these factors, soiling has been revealed as one of the most relevant causes diminishing the PV yield, mainly in arid zones or deserts. The effect of soiling on the PV performance can be analyzed by means of I–V curves measured simultaneously on two PV panels: one soiled and the other clean. To this end, two I–V tracers, or one I–V tracer along with a multiplexer, are needed. Unfortunately, these options are usually expensive, and only one I–V tracer is typically available at the site of interest. In this work, the design of a low-cost multiplexer is described. The multiplexer is controlled by a low-cost single-board microcontroller manufactured by ArduinoTM, and is capable of managing several pairs of PV panels almost simultaneously. The multiplexer can be installed outdoors, in contrast to many commercial I–V tracers or multiplexers. This advantage allows the soiling effect to be monitored on two PV panels, by means of I–V indoor tracers. I–V curves measured by the low-cost multiplexer are also presented, and preliminary results are analyzed.