Performance of grid-tied PV facilities based on real data in Spain: Central inverter versus string system

Two complete years of operation of two grid-tied PV facilities is presented. Energetic and economic performance of both installations has been compared. Located in the same place, the installation of these facilities followed the same construction criteria – PV panels, panel support system and wiring – and the facilities are exposed to the same atmospheric temperature and solar radiation. They differ with regard to their inverter topology used: one facility uses a central inverter and the other a string inverter configuration. The performance of the facilities has been determined using a procedure based on a small number of easily obtained parameters and the knowledge of the analyzed system and its operation mode. Electrical losses have been calculated for both systems and a complete comparison between them has been carried out. The results have shown better performance for distributed system in economic and energetic terms.Spanish Government (Grant ENE2011-27511) and the Department of Culture and Education of the Regional Government of Castilla y León, Spain (Grant BU358A12-2)

Estimation of photovoltaic potential for electricity self-sufficiency: A study case of military facilities in northwest Spain

Renewable energies, including photovoltaic energy, are attracting widespread international attention, in reaction to worsening environmental problems and the diminishing long-term sustainability of fossil fuel energies. In this work, the potential benefits of installing photovoltaic panels on several buildings at the Spanish Naval Military School (Escuela Naval Militar, ENM) of Mar ın are considered. The two salient advantages are significant economic savings from the production and the sale of electricity to the Spanish Electricity Network and achieving selfsufficiency in electricity requirements. Consequently, the main objective of this work is to estimate the energy potential of photovoltaic installations on the roofs of the ENM buildings. This is the first time that a project of this nature and size is presented to the Spanish Navy. To that end, a three-dimensional geographic analysis of the buildings is performed using three freeware software: Trimble SketchUp, Skelion, and Photovoltaic Geographical Information System. An economic study is also conducted to determine the feasibility of the installations, by estimating the Net Present Value of the photovoltaic installation and the Internal Rate of Return associated with the project. Subsequently, a sensitivity analysis that considers the most important parameters for the calculation of the amortization period is reported. The results show that the installation could fulfill the ENM electrical demands and could, in addition, generate significant economic benefits. The conclusions end with a recommendation to consider the merits of the proposed solution.Regional Government of Castilla y Le on (Ref. BU034U16), under European Regional Development Fund, and the Spanish Ministry of Economy, Industry and Competitiveness under the IþD þ i state programme Challenges for the Society (Ref. ENE-2014-54601-R). One of the authors, David Gonz alez Pe~na, thanks Junta de Castilla-Le on for economic support (PIRTU Program, ORDEN EDU/301/2015

Analysis of solar direct irradiance models under clear-skies: Evaluation of the improvements for locally adapted models

Direct solar irradiance has to be determined for the design of many energy applications such as photovoltaic systems and concentration systems, and the generation of solar potential maps for energy use. Knowledge of the accurate values of radiation components in a local area will allow optimal sizing of solar energy conversion systems. The estimated values of direct solar irradiance from models are still necessary at those sites where no measurements are available. In this work, different models used for the estimation of the direct component of solar irradiance are analyzed. First, an evaluation of the performance of eight existing original models was performed from which three were selected. Second, the selected models were calibrated to adapt them to our studied geographical area, which is the important aspect of this work, and an assessment of performance improvements for locally adapted models is reported. Experimental data consisted of hourly horizontal global, direct, and diffuse solar irradiance values, provided by the National Meteorological Agency in Spain (AEMET) for Madrid. Long-term data series, corresponding to a total period of time of 32 years (1980–2011), have been used in this study. Only clear sky models were treated at present. The three selected models were adapted to the specific location of Madrid, and root mean square error (RMSE) and mean-biased error were determined. By comparing the performance in the direct horizontal irradiance estimation from existing original and the corresponding locally adapted models, it is found that the values of RMSE decreased from 9.9% to 5.7% for the Louche model, from 7.8% to 7.4% for the Robledo-Soler model, and finally from 8.8% to 6.7% for the European Solar Radiation Atlas model. Thus, significant improvements can be reached when parametric models are locally adapted. In our case, it is up to approximately 4% for the Louche model. It is expected that calibrated algorithms presented in this work will be applicable to regions of similar climatic characteristics.Spanish Government (grant ENE2011-27511) and the Department of Culture and Education of the Regional Government of Castilla y León, Spain (grant BU358A12-2

Effects of Wind Speed and Direction on Monthly Fluctuations of Cladosporium Conidia Concentration in the Air

This study determined the relationship between airborne concentration of Cladosporium spp. spores and wind speed and direction using real data (local wind measured by weather station) and modelled data (air mass flow computed with the aid of HYbrid Single Particle Lagrangian Trajectory model). Air samples containing fungal conidia were taken at an urban site (Worcester, UK) for a period of five consecutive years using a spore trap of the Hirst design. A threshold of ≥6000 s m−3 (double the clinical value) was applied in order to select high spore concentration days, when airborne transport of conidia at a regional scale was more likely to occur. Collected data were then examined using geospatial and statistical tools, including circular statistics. Obtained results showed that the greatest numbers of spore concentrations were detected in July and August, when C. herbarum, C. cladosporioides and C. macrocarpum sporulate. The circular correlation test was found to be more sensitive than Spearman’s rank test. The dominance of either local wind or the air mass on Cladosporium spore distributions varied between examined months. Source areas of this pathogen had an origin within the UK territory. Very high daily mean concentrations of Cladosporium spores were observed when daily mean local wind speed was vs ≤ 2.5 m s−1 indicating warm days with a light breeze

Evaluation of the vertical sky component without obstructions for daylighting in Burgos, Spain

Daylight availability knowledge is the first step for an energetic and visually efficient building and city design. It can be estimated with the Vertical Sky Component (VSC), which is defined as the ratio of the vertical diffuse illuminance over the unobstructed horizontal diffuse illuminance, simultaneously measured at the same point. These illuminance magnitudes are obtained from luxmeter measurements but these data are scarce. Alternatively, VSC can be obtained from prior knowledge of the sky illuminance distribution, which can be measured with a sky scanner device or by reference to the CIE (Commission Internationale de L’Éclairage) Standard classification for homogeneous skies. Both approaches are compared in this study. The coherence of the results obtained for the four cardinal orientations are analyzed by applying classical statistical parameters and luxmeter measurements as references for the results. The measurement campaign was completed between September 2016 and January 2019 in Burgos (Spain), as representative case study and specific contribution of this work. It was observed that the VSC values were higher than 100 in many cases: 21.94% for the south- and 33.6% for the east-facing vertical surfaces. The study highlights the good daylighting conditions in Burgos, mainly due to the predominance of clear skies over much of the year. This fact implies high daylight availability that, with efficient city planning and building design, could potentially lead reduction energy consumption of buildings, improvements in visual comfort, and the well-being of occupants.Junta de Castilla y León | Ref. EDU / 667/2019Ministerio de Ciencia, Innovación y Universidades | Ref. RTI2018-098900-B-I00Junta de Castilla y León | Ref. EDU / 556/201

Implementation of PV plants in Spain: A case study

The implementation process of a photovoltaic system and its connection to the national grid in Spain is examined from an economic, an administrative and a legal standpoint. In the first place, this case study describes the solar farm, and it goes on to examine the economic aspects of electricity production, its associated costs, and relevant grants and financial subsidies. Finally, problems related to the administration of the project and the issuing of permits by local and regional authorities are discussed.PV grid-connected systems PV production PV support Administrative process