Search

The Spanish government is a strong advocate of reducing CO2 emissions and has made a clear commitment to the implementation of renewable energies. As reflected in Spain's National Energy and Climate Plan (NECP), its objective is to double the current capacity of pumped hydropower storage (PHS) plants by 2030. Therefore, the study presented here is both current and forward-looking. This paper presents the results of the analysis of the technical potential of installing floating photovoltaic (FPV) plants at 25 PHS plants in Spain, i.e., the total capacity of Spanish hydropower plants. The study was conducted using various assessment indicators: the global horizontal irradiance ratio, electrical efficiency ratio, area required ratio, pumping area ratio, volume ratio of water pumped per day, and achievable power ratio. In summary, the following conclusions can be drawn: (i) The global horizontal irradiance ratio indicates whether a FPV plant is economically viable. From this point of view, the Aguayo PHS plant and the Tanes PHS plant are not suitable, as this ratio is very low; (ii) the compliance with the electrical efficiency ratio is flexible, and all hydropower plants meet this criterion; (iii) maximising the use of the assigned grid connection capacity is one of the goals sought by electrical companies when implementing FPV plants at existing PHS plants. The following hydropower plants are not suitable for the implementation of an FPV plant in view of the following: La Muela I, La Muela II, Aguayo, Sallente, Aldeadavila II, Moralets, Guillena, Bolarque II, Montamara, and IP; (iv) if the aim is energy storage, the following hydropower plants are not suitable for the implementation of an FPV plant: the La Muela I, La Muela II, Tajo de la Encantada, Aguayo, Sallente, Aldeadavila II, Conso, Moralets, Guillena, Bolarque II, Tanes, Montamara, Soutelo, Bao-Puente Bibey, Santiago de Jares, IP, and Urdiceto; (v) if the aim is to expand an FPV plant already installed at a PHS plant, the following hydropower plants do not meet this criterion: the La Muela I, La Muela II, Aguayo, Sallente, Aldeadavila, Moralets, Guillena, Bolarque II, Montamara, and IP. There are only eight hydropower plants that meet conditions (i), (iii) and (iv): the Villarino, Torrejon, Valparaiso, Gabriel y Galan, Guijo de Granadilla, Pintado, and Gobantes. [ABSTRACT FROM AUTHOR]

Copyright of Crónica Tributaria is the property of Instituto de Estudios Fiscales, Ministerio de Hacienda y Funcion Publica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Soiling of PV modules is an issue causing non-negligible losses on PV power plants, between 3 and 4% of the total energy production. Cleaning is the most common way to mitigate soiling. The impact of the cleaning activity can be significant, both in terms of cost and resources consumption. For these reasons, it is important to monitor and predict soiling profiles and establish an optimal cleaning schedule. Especially in locations where raining is irregular or where desert winds carry a high concentration of particles, it is also important to know how precipitation and dust events affect the soiling ratio. This paper presents a new model based on environmental conditions that helps the decision-making process of the cleaning schedule. The model was validated by the analysis of five large grid-connected PV plants in Spain over two years of operation, with a total power of 200 MW. The comparison between the model and soiling sensors at the five locations was included. Excellent results were achieved, the mean difference between sensors and model being 0.71%. [ABSTRACT FROM AUTHOR]

In recent years, important regulatory changes have been introduced in Spain in the fields of self-consumption and energy tariffs. In addition, electricity prices have risen sharply, reaching record highs in the last year. This evidences the need to conduct new research studies in order to provide an accurate picture of the profitability of battery energy storage systems and photovoltaic systems. This paper proposes a complex simulation tool developed to assist in the optimal design of these kinds of facilities. The tool is used in this study to analyze the benefits of including batteries in PV systems under different self-consumption models, different consumer profiles and different locations across the country. The research results indicate that at current electricity prices, the use of batteries is less profitable than selling excess energy to the grid, unless the price of batteries drops drastically by more than 50% in all the cases analyzed. However, at current battery prices, they become a valuable resource in facilities that do not feed energy surplus into the grid. [ABSTRACT FROM AUTHOR]

In this paper, the main objective is the simulation of the electric supply for homes in remote areas located in Morocco (Oujda and Ouarzazate), Spain (Granada), and Algeria (Bechar). This simulation study is divided into two ideas, the first one is to optimize the hybrid system under a varied number of houses and the second part is to fix it in chosen values. This work relied on the particle swarm optimization (PSO) method to optimize and analyze the proposed stand-alone photovoltaic/wind/diesel/battery hybrid system. MATLAB software is used to run the simulations and to carry out the optimal solutions of the optimized system using a developed PSO algorithm. The PSO approach contains five principal operator axes, which are problem definition, PSO initial parameters, initialization, PSO main loop, and then run of the algorithm. Optimizing the system component sizes and reaching the minimum cost of energy (COE) were the function objectives of this optimization study. Moreover, calculation of the hydrogen production from the generated energy by PV and wind systems is performed. [ABSTRACT FROM AUTHOR]

• Pioneer Spain: first country to include in grid code the synthetic inertia capability. • Synthetic inertial response of a PV inverter studied based on the Spanish grid code. • Analyzed the role of power plant controller in the dynamic response of the facility. • PV system able to contribute to frequency control providing an inertial response. As the large-scale integration of renewable energy grows, inertia in power systems is reduced, which causes the rate of change of frequency to increase and worsens the frequency nadir during disturbances. There is, therefore, an urgent need to accelerate the development of international standards and regulations that require solar PV systems and other renewable installations to also contribute to stability in the network by emulating inertia. Spain is a pioneer in this field: it is currently the only country that includes the synthetic inertia technical requirement in its grid code. In this context, the present paper analyzes the synthetic inertial response of a PV system model that forms part of an actual PV power plant in Spain under two scenarios, according to its grid code: i) when measurements are conducted at the power conversion PV system level and hence only its control algorithms are executed; and ii) when measurements are conducted at the power plant level and the power plant controller also influences the response of the entire installation. Among its aims, this paper seeks to thoroughly assess the response of an actual PV power conversion system that has the capability of actively contributing to frequency regulation in a network and to critically analyze the suitability of having a power plant controller when the PV facility contributes to power-frequency control by means of an inertial response. The results reveal, at the power conversion PV system level, that the inertia emulation module significantly reduces the response times of the installation to changes in frequency -by more than 68% in the worst case under frequency increases, and by 73% under frequency decreases, thus contributing to more rapid power-frequency regulation in the network. However, at the power plant level, the power plant controller disturbs the PV power conversion system's behavior and causes the opposite effect: response times increase -up to more than 7% in the most unfavorable case when the inertia module is enabled. [ABSTRACT FROM AUTHOR]

Due to high competitiveness in the PV sector, despite the low degradation rate of crystalline silicon PV modules (below 0.5%/year), it is still important for utilities to know its actual value due to its impact on energy yield and hence, profitability, over the lifetime of a PV plant. However, uncertainties related to both the influence of downtime periods due to problems that may appear under normal operation of a commercial PV plant and to the measurement of degradation rates at PV plant level make this a challenging task. In order to obtain a significant value, in this paper, three measuring methods with different uncertainty sources are used for 82 MWp of PV modules on different locations in Spain and Portugal over 10 years. According to the different methods used and PV plants analyzed, excluding PV plants with problems, a range of degradation rates between 0.01 and 0.47%/year has been found. The overall average value observed is 0.27%/year. The findings of this work have also revealed the great importance of good operation and maintenance practices in order to keep overall low degradation rates. [ABSTRACT FROM AUTHOR]

Solar cells lose efficiency as the operating temperature increases under normal operating conditions, resulting in a very significant power output reduction. This issue is most relevant in areas with the highest photovoltaic energy harvesting potential, where irradiance and ambient temperature are particularly high. A novel cooling system for commercial photovoltaic modules based on low-enthalpy geothermal cooling is proposed in this paper. Excess heat is evacuated from the solar module in a clean and efficient manner by a single-phase and close-loop cooling circuit that uses the underground as a natural heatsink. In addition, a thermoelectrical theoretical model is presented, that allows the optimization of the flowrate and the maximization of the extra power generation of the cooled module. A prototype was manufactured and tested in outdoor conditions in September 2021 in Spain. Test results are in good agreement with the theoretical model, which has been used for prediction of the performance of the system for a typical meteorological year in the region. A peak efficiency improvement of 10.7% is calculated for the month of July, with an optimal flowrate of 1.8 l/min per square meter of solar module. A yearly weighted average power gain of up to 4.9% is also calculated. [ABSTRACT FROM AUTHOR]

Fluctuations of the incoming solar irradiance impact the power generation from photovoltaic and concentrating solar thermal power plants. Accurate solar nowcasting becomes necessary to detect these sudden changes of generated power and to provide the desired information for optimal exploitation of solar systems. In the framework of the International Energy Agency's Photovoltaic Power Systems Program Task 16, a benchmarking exercise has been conducted relying on a bouquet of solar nowcasting methodologies by all-sky imagers (ASI). In this paper, four ASI systems nowcast the Global Horizontal Irradiance (GHI) with a time forecast ranging from 1 to 20 min during 28 days with variable cloud conditions spanning from September to November 2019 in southern Spain. All ASIs demonstrated their ability to accurately nowcast GHI, with RMSE ranging from 6.9% to 18.1%. Under cloudy conditions, all ASIs' nowcasts outperform the persistence models. Under clear skies, three ASIs are better than persistence. Discrepancies in the observed nowcasting performance become larger at increasing forecast horizons. The findings of this study highlight the feasibility of ASIs to reliably nowcast GHI at different sky conditions, time intervals and horizons. Such nowcasts can be used either to estimate solar power at distant times or detect sudden GHI fluctuations. • ASI-based GHI nowcasts outperform persistence model under cloudy conditions. • Under clear skies, three ASIs reveal more accurate nowcasts than persistence. • ASIs forecasts are more accurate from persistence at increasing forecast horizons. [ABSTRACT FROM AUTHOR]

Heating up of photovoltaic modules during operation results in a significant power output reduction. This effect is especially relevant in regions with the highest photovoltaic potential, where irradiance and ambient temperature are particularly high. In this paper, a novel low enthalpy geothermal cooling system that improves the efficiency of a commercial solar module is described and experimentally validated. Two heat exchangers, one attached to the backside of the module, and another introduced inside a 15 m deep borehole, are connected in a closed circuit. A water-based coolant is pumped through the system, evacuating the excess heat from the module, and dissipating it underground in a clean and efficient manner, without additional water consumption after filling the system. The performance of the cooling system was experimentally tested by implementing it, for the first time, in a single-axis solar tracking isolated photovoltaic facility. Extensive tests were carried out in Spain, between September 2021 and August 2022 under a wide variety of environmental conditions. The efficiency improvement system has demonstrated its technical feasibility over a one-year period, showing a peak net efficiency improvement up to 13.4 %. Moreover, a positive net efficiency improvement has been demonstrated all year long, even during the winter months. [ABSTRACT FROM AUTHOR]

Solar PV technologies have been expanding rapidly, and the installed power has increased, especially in the last decade. Their inclusion in university buildings arises as a key factor for sustainable transition in cities, since they have an important potential as case studies for urban experimentation positive effects on students and other stakeholders. This paper proposes a method to determine the availability for installing solar PV in universities' rooftops, considering simulation and cartography data, together with a final experimental validation stage. Unavailable areas for each rooftop are determined, including obstacles, the inner use of the rooftop and shadowed areas. Finally, the method verifies the technical suitability for all the proposed scenarios and applies an economic-environmental multicriteria evaluation to select the most suitable one. The methodology is validated in the Universitat Politècnica de València Vera-Campus. In total, 88913 m2 of the rooftops are suitable for solar PV incorporation, representing 48 % of the total surface. 52 % of the solar PV installable capacity takes place in surfaces which can incorporate more than 100 kW, 20.6 % between 50 and 100 kW and 27.4 % less than 50 kW. Finally, the multicriteria evaluation proved that the scenario with all the possible installations is the most suitable one. [ABSTRACT FROM AUTHOR]

The increased penetration of renewable energy sources (RESs) as an effective mechanism to reduce carbon emissions leads to an increased weather dependency for power and energy systems. This has created dynamic operation and degradation phenomena, which affect the lifetime estimation of the assets operated with RESs. For the reliable and efficient operation of RES it is crucial to monitor the health of its constituent components and feature selection is a crucial step for building robust and accurate health monitoring approaches. In this context, this paper presents a probabilistic feature selection approach, which probabilistically weights and selects features through a heuristic and iterative process for an improved asset lifetime estimation. Power transformers are key power grid assets and they are used to demonstrate the validity and impact of the proposed approach. The approach is tested on two different photovoltaic power plants operated in Spain and Australia. Results consistently show that the proposed feature-selection approach reduces the prediction error and consistently selects relevant features. The approach has been applied to transformer lifetime estimation, but it can be generally applied to assist in the lifetime estimation of other components operated in RESs. Part of the studies presented here as well as source codes are all open-source under the GitHub repository https://github.com/iramirezg/FeatureSelection. • Probabilistic feature selection approach for improved asset lifetime estimation. • Integration of environmental features for improved renewable-operated asset lifetime. • Systematic and robust feature weighting methodology. • Improved transformer lifetime estimation including sensor and environmental data. • Validated on two real photovoltaic power plant case studies. [ABSTRACT FROM AUTHOR]

The Spanish renewable energy sector has experienced phenomenal growth over the past decade due to implementation of regulatory frameworks that have encouraged the rapid deployment of some renewable energy technologies particularly solar photovoltaic (PV), wind, and biomass. But the unstable regulatory frameworks, price, and quantity caps on renewable technologies and recent initiative of temporary suspension of subsidies for any new solar, wind, cogeneration or waste incineration projects have declined the growth of production of electricity from renewable energy sources (RES-E). The aim of this paper is to provide the current situation of promotion measurers for RES-E particularly for solar PV in Spain and regulatory changes since the feed-in-tariff was put in place in Spanish solar market. The paper also provides a critical analysis of the Spanish policy instruments and regulatory frameworks that contributed in the tremendous growth of solar PV. It also analyses the new policy instruments necessary to achieve declared 2020 RES-E targets. [ABSTRACT FROM AUTHOR]

Large deployment of photovoltaic (PV) installation worldwide demands reliability assurance of the systems to maintain the confidence in the markets. With the diversity of PV applications, it is essential the detection of circumstances that can be the root of failure mechanisms, such as transportation and installation of the modules. They are one of the main sources of induced vibrations, which, in its turn, can provoke defects and damages in the PV modules. In this work, we have measured and analyzed tri-axial accelerations and mechanical vibration that photovoltaic crystalline modules withstand during transportation by road, including loading and unloading operations. We have also analyzed the natural oscillation frequencies, the resonance phenomena and the highest impacts. It is concluded that a proper fastening of the load inside the truck is necessary and that high impacts during loading and unloading should be avoided. Packing the modules to reduce vibrations is also recommendable. Several solutions to perform this are proposed. [ABSTRACT FROM AUTHOR]

The integration of a CSP tower system with a PV solar field, sharing a thermal energy storage, is modeled and discussed. The tower system uses a new-design solid particle fluidized bed receiver integrated with a thermal storage, where hot particles are directly collected to store daily energy for overnight production of electricity. The PV solar field is aimed to supply the daily energy demand; when there is a surplus of PV energy production, the electric energy is converted to heat and accumulated in the thermal storage too. The integration of the two energy systems is modeled, building efficiency functions for all the sub-components of the integrated plant (heliostat field, receiver, storage, power block, PV field). Yearly simulations are performed for two different locations, Spain and Australia, obtaining that a system with a peak power of 10 MWe CSP + 15 MWe PV can supply—with a limited curtailment—a fraction of more than 60% (respectively, 62% and 68%) of a realistic electric load with a peak demand around 10 MW, to be compared with the 45/47% of the same load obtained adopting a PV-only system with the same overall peak power. In the integrated system, PV directly supplies 40/41% of the load, the remaining 23/28% being produced by the power block (mainly fed by the CSP). [ABSTRACT FROM AUTHOR]

The decreasing costs of solar photovoltaic (PV) technology have led to an exponential growth in the use of PV self-consumption systems. This development has encouraged the consideration of battery energy storage systems (BESS) as a potential means of achieving even more independence from the fluctuating grid electricity prices. As PV technology and energy storage costs continue to decline, both technologies will likely play an increasingly important role in the renewable energy sector. The profitability of batteries in PV self-consumption systems is largely influenced by the price of consumed electricity and the price at which surplus energy is remunerated. However, strategies in PV-BESS self-consumption systems typically do not take electricity prices into consideration as a variable for decision making. This study simulates and analyzes battery operation strategies that take into account electricity prices. The simulations are performed using real industrial consumption data and real electricity prices and tariffs, they cover the entire lifespan of the batteries, and include aging and degradation due to use and cycling. A techno-economic model is used to evaluate the advantages of incorporating these battery operational strategies into an actual PV-BESS system. The results demonstrate that the proposed strategies enhance the savings that batteries can provide. [ABSTRACT FROM AUTHOR]

ABSTRACT Semprius has a novel micro-cell based approach that addresses the cost, performance and reliability requirements of high concentration photovoltaic systems. A design that has a geometric concentration ratio of >1100 suns and three-junction 0.36 mm2 micro-transfer printed cells is now complete. A module efficiency of 33.9% at a direct normal irradiance of 850 W/m2 and cell temperature of 25°C has been independently validated for this design by the Instituto de Energia Solar at the Universidad Politecnica de Madrid. This is the highest measured module efficiency for any PV module, designed for commercial use. Several research, development and demonstration (RD&D) systems have been installed with these modules to collect early on-sun data and validate the technology. This paper presents module characterization and on-sun system results from a 3.5-kWp RD&D system installed at Instituto de Sistemas Fotovoltaicos de Concentracion, Puertollano, Spain by Semprius and Siemens. In addition, results from cleaning experiments and thermal performance of the system are presented from another RD&D system in Tucson. Comparisons of the performance of the Tucson RD&D system with co-located one-axis Si and fixed-tilt Si systems are also presented. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: The present production and use of energy are causing depletion of resources and serious environmental problems. Accordingly, more and more countries are examining a whole range of new policies and technology issues to make their energy futures “sustainable,” thus increasing governmental incentives for technology providers and utility mandates to incorporate significant levels of renewable resources. Hand-in-hand with the sustainable development initiative, in recent years the concept of a “Smart Grid” for the delivery of energy to consumers has emerged. Existing distribution networks were not designed to accept extensive distributed generation (DG). The actual paradigm may change in the near future impelled by a worldwide increasing of DG penetration in distribution grids. This paper presents the status and content of Spanish legislation on DG. Fundamental considerations are first discussed, exclusively regarding the grid-interconnection requirement. This paper also analyses the relationship between that guidelines and recognized international standard in a systematic way. Major requirement areas include general specifications, safety and protection strategies, and power quality requirements. This study reveals the diversity of requirements for DG grid connection coexisting, considering both the national and the international context; this stresses the urgent need for international harmonization. It is interesting to note that in Spain (as in most of the European countries), protections for LV photovoltaic systems are defined but not for the rest of the distributed generation technologies in low voltage. Thus, one could conclude from this study that probably the most important barriers are the lack of adequate requirements and procedures. [Copyright &y& Elsevier]

Abstract: A rigorously founded assessment of the potential of renewable energies is essential for the development of energy policies and regulations. Usually, a hierarchy of potentials are calculated which gradually include restrictions for the use of a specific renewable resource. This paper deals with the estimation of the technical potential of roof-integrated photovoltaic systems. The most restrictive step when estimating this potential for large-scale territories is the estimation of the roof available area in existing buildings, for which no direct data exists. The methodology proposed in this paper allows to estimate the roof area available for solar applications and also quantify the error made in this estimation. It is based on easily accessible data (such as land uses and population and building densities) and on a statistically representative stratified-sample of vectorial GIS maps of urban areas. The main point in this sampling process is that the stratification is done based on a finite set of average building typologies which comprises every urban area in the region of study. An interesting characteristic emerging from the proposed methodology is its scalability and the possibility of being used from regional to continental scales. This methodology is applied in this work to Spain and a mean available area for photovoltaic equipment on roofs of . with a confidence level of 95% is obtained. Additionally, results are given for the technical limit of production of roof-integrated photovoltaic energy. [Copyright &y& Elsevier]

Solar photovoltaic self-consumption is an attractive approach to increase autarky and reduce emissions in the building sector. However, a successful deployment in urban rooftops requires both accurate and low-computational-cost methods to estimate the self-consumption potential and economic feasibility, which is especially scarce in the literature on net billing schemes. In the first part of this study, a bottom-up GIS-based techno-economic model has helped compare the self-consumption potential with net metering and net billing in a Mediterranean municipality of Spain, with 3734 buildings in total. The capacity was optimized according to load profiles obtained from aggregated real measurements. Multiple load profile scenarios were assessed, revealing that the potential self-sufficiency of the municipality ranges between 21.9% and 42.5%. In the second part of the study, simplified regression-based models were developed to estimate the self-sufficiency, self-consumption, economic payback and internal rate of return at a building scale, providing nRMSE values of 3.9%, 3.1%, 10.0% and 1.5%, respectively. One of the predictors with a high correlation in the regressions is a novel coefficient that measures the alignment between the load and the hours with higher irradiance. The developed correlations can be employed for any other economic or demand scenario. [ABSTRACT FROM AUTHOR]

The rapid expansion of photovoltaics within the global energy market requires increasing use of land, a limited resource where different uses compete. In this respect, photovoltaic systems that combine electricity generation with land use for crops are becoming increasingly important. This article proposes an analytical model validated in an operating bifacial photovoltaic plant during the summer months. This analytical model considers view factors and heat transfer calculations, as well as an electrical model of the photovoltaic modules. A study was carried out on a commercial solar power plant (11.24 MWp) in Seville, southern Spain, where different vegetal species were planted in two strings, and string performance was monitored. Nine crop species with different irrigation and light requirements, offering different albedo parameters and thermal characteristics. The results show advantages from the point of view of module temperature and power gain. This paper provides regressions for the characterisation of the photovoltaic agricultural plant, with R2 higher than 85%, both for module temperature and energy exported in the string with crops. [Display omitted] [ABSTRACT FROM AUTHOR]

Spain has shifted from a predominant position in the worldwide market according to the accumulated PV power installed, to an irrelevant level where it is even no longer present at the PV market survey; but not always this has been the situation. The Spanish Government have promoted renewable energy policies which have turned very rapidly from a promising scenario, especially in the 2004–2008 period, into an unstable situation not only for future investors in this technology, but also for current owners that have been witnesses of a decrease in their profitability expectations. Furthermore, although the retroactive measures that have been applied to the owners of these PV plants could be, paraphrasing the Government words, “reasonable profitable”, the problem arises when they may be unable to afford the annual liquid assets of the funding mechanism chosen for their PV investments. Therefore, in a scenario where in the last decade more than 12 laws and Royal Decrees have been promulgated in Spain, it is interesting to review the effects in the profitability and cost parameters that this legislation has had on the PV market, on the owners and also on prospective investors. In this paper a complete economic profitability and cost analysis based on the NPV, IRR and LCOE has been undertaken for the case of Spain since 1998, correlating it to the evolution of the legislative framework applicable to the photovoltaic technology. [ABSTRACT FROM AUTHOR]

Rooftop photovoltaic generation can help cities become key players in the transition to clean energy. The optimal solar photovoltaic production on rooftops depends on two angles: tilt angle and azimuth angle. It is accepted in all studies that the ideal orientation of photovoltaic modules is toward the south (north) in the northern hemisphere (south). In contrast, the determination of the optimum tilt angle is more complex, and there are different equations for its calculation. Most of these equations do not take albedo into account. In this work, 47 Spanish province capitals representing the most populated cities have been studied with different equations for the calculation of the optimum annual tilt angle (Technical report by the Spanish Institute for the Diversification and Saving of Energy (IDAE), Lorenzo's and Jacobson's equation) and different types of albedo. Accounting for the geographical and the meteorological conditions of the cities, we analyzed the optimum tilt angle through a Mathematica© optimization code. The influence that different variables have on optimum tilt angle has been quantified by means of the term relative energy harvested. The use of the equations as a function of latitude increases the annual relative energy harvested by increasing the albedo. When the albedo is 0.2, the annual relative energy harvested is very similar in all equations. Comparing to the method that maximizes the total irradiation incident on a tilted surface, the minimum and maximum value of the percentage of relative energy harvested per year were 0.01 and 2.50% for the IDAE guideline, 0.00 and 2.38% for Lorenzo's equation, 0.00 and 2.46% for Jacobson's equation. A simplified polynomial regression model to estimate optimum tilt angle as a function of latitude, altitude and albedo has been proposed as well. [ABSTRACT FROM AUTHOR]

This paper is to select the best locations to build solar photovoltaic farms (large grid-connected photovoltaic systems which have more than 100 kW p of installed capacity), with the coast of Murcia in the southeast of Spain being used as an example. In order to solve the problem, the suitable locations to implant such facilities will be identified by a Geographical Information System (GIS). To obtain the weights of the criteria which influence the proposed problem, the Analytic Hierarchy Process (AHP) will be employed. Then, the suitable locations will be evaluated and classified using two different multi-criteria decision methods, the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) and ELimination and Choice Expressing Reality (ELECTRE), in this case the version TRI. We are thus also able to establish a comparison between the two methods. This comparison demonstrates how although the results do not completely coincide, some similarity can be seen between the two methods. [ABSTRACT FROM AUTHOR]

Costs for High Concentrator Photovoltaic (HCPV) power plants dropped dramatically during 2013 and are expected to continue to fall in the next few years. Moreover, when viewed from the perspective of life cycle cost, HCPV becomes even more competitive than other renewable technologies in some geographical areas. Consequently, an analysis of the economic feasibility of the HCPV systems in future scenarios is necessary for comparison with other electricity generation technologies. One of the methods commonly used for the economic feasibility analysis in electricity generation projects is the levelised cost of electricity (LCOE). In this paper a cost analysis of electricity generation of HCPV technology in Spain by using the LCOE has been carried out. The results obtained in this LCOE analysis show that in 2020 the LCOE will be able to reach values for HCPV systems from 0.035 to 0.080 €/kW h, lower than LCOE for conventional PV systems, in some geographical areas of Spain. The results obtained in this analysis have been shown in innovative maps. [ABSTRACT FROM AUTHOR]

From mid-2007 to September 2008, the Spanish PV sector experienced an investment boom, which led to a ten-fold increase in solar PV deployment. The concern of the government about the large increase in the associated support costs through a feed-in tariff led to the implementation of several cost-containment regulations. These included a cap on the electricity generation being eligible for support, a grid access charge, a generation charge, a shortening of the support period and the updating of tariffs below the consumer price index. The aim of this paper is to analyze the impact of those cost-containment mechanisms on the profitability of solar PV plants in Spain. The results show that these measures have had a moderate impact on the profitability of those plants, which is still relatively high, with internal rates of return which are always above 7% in all the simulated cases. However, their impact is mediated by different features of the plant, including the levels of the initial investment (upfront costs), borrowing and operation and maintenance (O&M) costs. It is also mediated by policy variables (such as changes in the tariff-updating method and the level of the grid-connection charges) and by other variables, e.g., the interest rates of loans. The specific impact of each of the cost-containment measures has also been analyzed. Our findings show that the generation charge has the greatest impact, followed by the change in the tariff-updating mechanism, the generation cap, the shortening of the support period and the grid access charge. [ABSTRACT FROM AUTHOR]

The paper analyses and compares the merit order effects of photovoltaic and wind power on final electricity prices in the Spanish spot market and the cost of electricity tariffs. Artificial intelligence techniques are used to model the electricity auction clearing process. Several algorithms are studied before the M5P learning algorithm is finally applied to create a tree model of the spot market. Electricity tariffs for domestic consumers are also recalculated for fictional scenarios with no photovoltaic or wind power production. The conclusion is that the influence of photovoltaic and wind power is uneven. Wind power reduces final electricity prices by €9.10/MW h, generating an overall saving for the system of €364.0 million and for the average domestic consumer of €1.95 using 2012 figures; photovoltaic power reduces electricity prices by €2.18/MW h, generating an overall cost overrun for the system of €2034.1 million and for the average domestic consumer of €38.82. [ABSTRACT FROM AUTHOR]

Photovoltaics (PV) has reached high level of maturity in terms of material efficiency and low production costs. For this reason, nowadays, lot of emphasis is put on the reduction of the operation and maintenance costs. Soiling is one of the issues that most affect these costs. So, the understanding of its electrical and economic implications is essential to optimize the cleaning routines and minimize the associated costs. This paper investigates the possibility of estimating soiling directly from PV performance data, without the need of installing specific soiling monitoring equipment, which typically needs careful and regular maintenance. Five analytical methods are evaluated and applied to the data of PV modules of different technologies (m-Si, CdTe and CIS). An experimental campaign is conducted in a location in Southern Spain with low-moderate levels of soiling. The methods show promising accuracies when used to obtain the soiling losses of a module, especially during soiling-intense and long dry periods. • Soiling losses were directly extracted from the performance data of PV modules. • The goodness of five different analytical methods was assessed. • These methods allow soiling to be quantified without need for additional sensors. • Each methodology was applied to PV modules of three different technologies. • The accuracies of the methods were higher in periods with greater soiling losses. [ABSTRACT FROM AUTHOR]

Abstract: An analysis of scientific publications on solar energy was conducted to determine whether public interest in the subject is mirrored by more intense research in the area. To this end, the research published by Spain and Germany, the two EU countries with the highest installed photovoltaic capacity, was analyzed based on Web of Science data. The results show that: solar output has risen substantially; solar research has a greater impact (measured in terms of citations) than publications on other renewables such as wind power; scientific production on solar energy is high in Germany and Spain, which together account for 51% of the total in the EU-27; the pattern of topics researched in the two countries is very similar; and their international collaboration is more intense than the world average and higher than in countries such as the USA, China or Japan. Collaboration between them is likewise intense. The main conclusion is the divergence in Germany and Spain between solar energy demand/output growth, being exponential, and the growth of research papers on the subject, which is linear. [Copyright &y& Elsevier]

Copyright of DYNA - Ingeniería e Industria is the property of Publicaciones Dyna SL and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: The cut-off of any subsidy or feed-in tariff that incentives the installation of new renewable energy systems which are close to the grid parity, is a reality in most of the European countries, but in the recent years the grid parity has worsened because of the global economic crisis. In the case of Spain, in addition to the economic problems, the photovoltaic sector has been dramatically damaged through a changeable regulatory framework, an excessive bureaucracy and the inclusion of additional fees or possible back-up tolls that are very prejudicial for the deployment of this sector. Nowadays, the current Spanish legislation mentions the possibility of self-consumption (totally or partially) of the electricity generated by PV or any renewable energy systems but, up to the date of this work, the law that regulates the administrative, technical and economic conditions for the net-metering of the electrical energy produced within the consumer׳s network, is still under a draft stage. In this paper it is analyzed the case of the University of Jaen, where it has been identified and simulated several PV systems on the roofs and parking lots of the University Campus, and considering the current electrical tariffs (hourly defined for the case of high power and high voltage consumers), it has been done a cost and economic analysis. As a result, it has been obtained an average Levelised Cost of Energy around 0.125€kWh−1, a discount payback time of 17.5 years or less, a positive Net Present Value and a nominal Internal Rate of Return of 8.48% in the worst case. Beyond that, it has been carried out a sensitivity analysis of the factors that have more influence in the profitability of these systems, like the initial investment cost, the PV electricity yield, additional taxes and the variations in the electricity price market. [Copyright &y& Elsevier]

Abstract: The assessment of the technical impact of photovoltaic-distributed generation (PV-DG) units on radial distribution systems (RDSs) is complex because of the probabilistic nature of their output power and the diversity of potential sites where they can be installed. This type of evaluation thus requires a multivariate probabilistic analysis involving non-Gaussian correlated random variables. In a previous study, we applied an analytical technique to assess this technical impact for a single 10-min period. In the research presented in this paper, this technique was improved so that it could be applied during a full year, assuming 10-min intervals for PV and load profiles. This is the time period required to accurately assess the effects of stochastic PV inputs, and to determine the improvement of power quality (PQ) parameters, based on current regulations. This article describes a case study for a rural RDS located in the region of Andalusia in the south of Spain with spatially correlated PV-DG units. Our objective was to improve the analytical technique and also the accuracy of probabilistic methods. In our opinion, this can enhance the operation and planning of PV-DG in RDSs and provides a better understanding of the effects of spatial PV dependence structures. [Copyright &y& Elsevier]

Abstract: Since 1998 the Spanish Government established a feed-in system where RES-E generators could choose between two alternatives: fixed feed-in tariff and premium. Nowadays, all RES-E 1 [1] RES-E: electricity from renewable energy sources. can be sold in the electricity market (getting an additional premium) except for solar photovoltaic. One important novelty established in 2007 is a cap and floor system for facilities under the premium option. The aim of this paper is to analyze and compare these two alternative options, fixed-FIT and premiums, which coexist at the same time in Spain, describe the evolution of both systems and evaluate its performance. The introduction of this support system in Spain led to very good results in terms of RES-E deployment. The main advantage of the premium option is that it is a scheme integrated in the electricity market. One disadvantage is that it can occasionally lead to overcompensation; one way to try to avoid it is to set a cap value. In order to evaluate the performance of this dual support system not only RES-E deployment has been assessed but also the policy stability, the adequacy of RES-E production to the electricity demand pattern and the changes in the investors’ behaviour. [Copyright &y& Elsevier]

Abstract: The fast growth of PV installed capacity in Spain has led to an increase in the demand for analysis of installed PV modules. One of the topics that manufacturers, promoters, and owners of the plants are more interested in is the possible degradation of PV modules. This paper presents some findings of PV plant evaluations carried out during last years. This evaluation usually consists of visual inspections, I–V curve field measurements (the whole plant or selected areas), thermal evaluations by IR imaging and, in some cases, measurements of the I–V characteristics and thermal behaviours of selected modules in the plant, chosen by the laboratory. Electroluminescence technique is also used as a method for detecting defects in PV modules. It must be noted that new defects that arise when the module is in operation may appear in modules initially defect-free (called hidden manufacturing defects). Some of these hidden defects that only appear in normal operation are rarely detected in reliability tests (IEC61215 or IEC61646) 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, overvoltage on wires, etc.). [Copyright &y& Elsevier]

Abstract: Assessing the correct operation of PV grid-connected systems (PVGCS) is paramount not only for mere energy and profitability concerns but also for safety reasons. Intended to this purpose, the IEC 62446 standard is open to some tests to be required in some circumstances, in addition to those stated in this document. Our work proposes a procedure to carry out quality checks in PVGCS complying with this standard and dealing with some tests not mentioned in it – namely, PV generator peak power measurement, inverter response and earth electrode measurement – so that the verification of the system gets more comprehensive. This procedure was carried out in six PV plants sited in different locations with a Mediterranean climate in Spain. The most remarkable results of this experimental campaign may be summarized as follows: an excellent on-site behavior of the inverters, in general very good figures for the isolation and earth electrode resistance and a scarcely relevant existence of hot spots. On the down side, some figures for the peak power of the tested PV generators well below their nominal value were found. The procedure described in this paper has proved to be a useful tool to assist in the verification of a PVGCS after installation and for subsequent re-inspection or maintenance. [Copyright &y& Elsevier]

Copyright of DYNA - Ingeniería e Industria is the property of Publicaciones Dyna SL and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: Predicting both PV module and generator performances under natural sunlight is a key issue for designers and installers. Five simple algebraic methods addressed to predict this behaviour in Mediterranean climates have been empirically validated. Firstly, the calibration in STC of all significant electrical parameters of both a monocrystalline and a polycrystalline silicon PV modules was entrusted to an accredited independent laboratory. Then, a 12-month test and measurement campaign carried out on these modules in the city of Jaén (Spain, latitude 38°N, longitude 3°W) has provided the necessary experimental data. Results show that (a) crystalline silicon PV module outdoors performance may be described with sufficient accuracy – for PV engineering purposes – only taking into account incident global irradiance, cell temperature, and using any one of two simple algebraic methods tried in this paper and (b) regardless the used method, poor results may be achieved if the PV specimens under study are not electrically characterised in STC prior to analysing their outdoors performance. Even so, the methods recommended in (a) perform best. [Copyright &y& Elsevier]

Abstract: Thermal energy collected from a PV-solar air heating system is being used to provide cooling for the Mataro Library, near Barcelona. The system is designed to utilise surplus heat available from the ventilated PV facade and PV shed elements during the summer season to provide building cooling. A desiccant cooling machine was installed on the library roof with an additional solar air collector and connected to the existing ventilated PV façade and PV sheds. The desiccant cooling cycle is a novel open heat driven system that can be used to condition the air supplied to the building interior. Cooling power is supplied to the room space within the building by evaporative cooling of the fresh air supply, and the solar heat from the PV-solar air heating system provides the necessary regeneration air temperature for the desiccant machine. This paper describes the system and gives the main technical details. The cooling performance of the solar powered desiccant cooling system is evaluated by the detailed modelling of the complete cooling process. It is shown that air temperature level of the PV-solar air heating system of 70°C or more can be efficiently used to regenerate the sorption wheel in the desiccant cooling machine. A solar fraction of 75% can be achieved by such an innovative system and the average COP of the cooling machine over the summer season is approximate 0.518. [Copyright &y& Elsevier]

Abstract: The study presented in this paper is part of a project where several companies, utilities and institutions have been working together to evaluate the limits and competitiveness of PV energy in Spain. One of the tasks carried out in this project has been dedicated to forecast possible future scenarios of grid-connected photovoltaic buildings in Spain, considering technological, economic, social and environmental aspects. To perform the study, a methodology based in PV-scenarios has been developed. This methodology allows the researcher to establish future scenarios defined by a set of parameters that will determine the overall progress in grid-connected BIPV (building integrated photovoltaics). In order to facilitate the analysis, the “ScenariosPV” software tool has been developed. This program has proved very useful to deal with PV parameters management, future scenarios analysis and detailed comparison. This methodology has been applied to estimate future PV-scenarios in Southern Spain. In an advanced scenario for the year 2020, the total grid-connected BIPV installed surface could reach 2,480,000m2, supplying as much as 1,872TJ per year, 10% of the electricity peak demand in the summertime and providing up to 25,000 jobs. [Copyright &y& Elsevier]

Abstract: Several methods for sizing stand alone photovoltaic (pv) systems has been developed. The more simplistic are called intuitive methods. They are a useful tool for a first approach in sizing stand alone photovoltaic systems. Nevertheless they are very inaccurate. Analytical methods use equations to describe the pv system size as a function of reliability. These ones are more accurate than the previous ones but they are also not accurate enough for sizing of high reliability. In a third group there are methods which use system simulations. These ones are called numerical methods. Many of the analytical methods employ the concept of reliability of the system or the complementary term: loss of load probability (LOLP). In this paper an improvement for obtaining LOLP curves based on the neural network called Multilayer Perceptron (MLP) is presented. A unique MLP for many locations of Spain has been trained and after the training, the MLP is able to generate LOLP curves for any value and location. [Copyright &y& Elsevier]

Featured Application: Featured Application: Several commercially available and free downloadable PV modelling software tools are compared with real data for three different photovoltaic power plants in operation over the past 12 years. Both annual and monthly results are analyzed. Prediction of energy production is crucial for the design and installation of PV plants. In this study, five free and commercial software tools to predict photovoltaic energy production are evaluated: RETScreen, Solar Advisor Model (SAM), PVGIS, PVSyst, and PV*SOL. The evaluation involves a comparison of monthly and annually predicted data on energy supplied to the national grid with real field data collected from three real PV plants. All the systems, located in Castile and Leon (Spain), have three different tilting systems: fixed mounting, horizontal-axis tracking, and dual-axis tracking. The last 12 years of operating data, from 2008 to 2020, are used in the evaluation. Although the commercial software tools were easier to use and their installations could be described in detail, their results were not appreciably superior. In annual global terms, the results hid poor estimations throughout the year, where overestimations were compensated by underestimated results. This fact was reflected in the monthly results: the software yielded overestimates during the colder months, while the models showed better estimates during the warmer months. In most studies, the deviation was below 10% when the annual results were analyzed. The accuracy of the software was also reduced when the complexity of the dual-axis solar tracking systems replaced the fixed installation. [ABSTRACT FROM AUTHOR]

Solar energy is in high demand due to its environmental benefits and economic potential; however, concerns remain about the total impact it holds. In 2020, for Spain, Castilla-La Mancha was the second autonomous community with the highest photovoltaic energy production. Thus, a systematic review on 15 large-scale PV solar energy projects was carried out to assess the industry impacts, through environmental impact assessment (EIA), within the Autonomous Community of Castilla—La Mancha. An estimation of these impacts from a pre-operational approach is presented, based on primary energy needs and emissions discarded during its life cycle due to the manufacture, operation, and recycling of the photovoltaic modules. Based on both the life cycle assessment (LCA) and EIA, the approaches were compared with the results obtained. The obtained results suggest that determining the actual impacts of power plants in this region could provide justified information for the public administration and technicians in the measures for the installation and operation of PV plants and the future benefits of renewable solar technologies. Furthermore, the results indicate the possibility to recognize the relationship between the size of the plant and a high generation capacity, with a shorter time to pay for emissions from the manufacture and recycling of panels, suggesting that it is around 1.66–2.08 years for the Castilla-La Mancha region. [ABSTRACT FROM AUTHOR]

The article examines the developments in the law of feed-in tariff (FIT) for solar photovoltaic (PV) electricity generation. Policy and legal issues surrounding capacity closure and capping of FIT schemes to new entrants are analyzed. It examines the use of capacity caps in Great Britain, Czech Republic, France, Spain and Australia. It reveals that caps are a blunt tool for constraining the effect of FIT on electricity prices.

Incident solar radiation modelling has become of vital importance not only in architectural design considerations, but also in the estimation of the energy production of photovoltaic systems. This is particularly true in the case of buildings with integrated photovoltaics (PV) systems having a wide range of orientations and inclinations defined by the skin of the building. Since solar radiation data at the plane of interest is hardly ever available, this study presents the analysis of two of the most representative transposition models used to obtain the in-plane irradiance using as input data the global and diffuse irradiation on the horizontal plane, which can be obtained by satellite-based models or ground measurements. Both transposition models are validated with experimental measurements taken in Murcia (southeast of Spain) and datasets provided by the photovoltaic geographical information system (PVGIS) and the National Renewable Energy Laboratory (NREL) for vertical surfaces facing the four cardinal points. For the validation, the mean bias deviation, root mean square error and forecasted skill were used as indicators. Results show that the error rate decreases slightly for clear days. Better results are also obtained by dismissing data with low solar elevation angles so as to avoid shadowing effects from the surroundings in the early and late hours of the day, which affects mainly the performance of the transposition models for west and east surfaces. The results highlight the potential of equator-facing façades in winter time when the received irradiation can be twice as much as the one collected by the horizontal plane. It is also noteworthy that the operating conditions of all façades are mainly low irradiance and medium temperature at these locations. [ABSTRACT FROM AUTHOR]

This project studies the conditions at which the maximum power point of a photovoltaic (PV) panel is obtained. It shows that the maximum power point is very sensitive to external disturbances such as temperature and irradiation. It introduces a novel method for maximizing the output power of a PV panel when connected to a DC/DC boost converter under variable load conditions. The main contribution of this work is to predict the optimum reference voltage of the PV panel at all-weather conditions using machine learning strategies and to use it as a reference for a Proportional-Integral-Derivative controller that ensures that the DC/DC boost converter provides a stable output voltage and maximum power under different weather conditions and loads. Evaluations of the proposed system, which uses an experimental photovoltaic dataset gathered from Spain, prove that it is robust against internal and external disturbances. They also show that the system performs better when using support vector machines as the machine learning strategy compared to the case when using general regression neural networks. [ABSTRACT FROM AUTHOR]