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Review of the performance of residential PV systems in Belgium
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The main objective of this paper is to review the state of the art of residential PV systems in Belgium by the analysis of the operational data of 993 installations. For that, three main questions are posed: how much energy do they produce? What level of performance is associated to their production? Which are the key parameters that most influence their quality? This work brings answers to these questions. A middling commercial PV system, optimally oriented, produces a mean annual energy of 892kWh/kWp. As a whole, the orientation of PV generators causes energy productions to be some 6% inferior to optimally oriented PV systems. The mean performance ratio is 78% and the mean performance index is 85%. That is to say, the energy produced by a typical PV system in Belgium is 15% inferior to the energy produced by a very high quality PV system. Finally, on average, the real power of the PV modules falls 5% below its corresponding nominal power announced on the manufacturer's datasheet. Differences between real and nominal power of up to 16% have been detected.
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... Shading Shading PV modules reduces PV output with losses as low as 1% with good system designs and a reasonable ground cover ratio [12]. Shading losses were estimated at 2% for residential systems in France and Belgium [89,90] and 5.99% for polycrystalline modules partially shaded by an electrical cable [91]. In this study, it was assumed that PV systems would be set up in flat terrain, that they would be isolated from the shading of vegetation and buildings and that systems would be optimized to reduce the impact of shading. ...
Small island developing states (SIDS) are the lowest emitters of greenhouse gases yet are the most vulnerable to the impacts of global climate warming. Many islands, such as the Caribbean islands, identified solar photovoltaics as a technology for reducing greenhouse gas emissions from their electricity sector. However, prefeasibility economic studies for photovoltaics are challenging as operational photovoltaic system data are nonexistent, and the measured solar radiation datasets are limited. Thus, a prefeasibility PV tool that uses ground-measured global horizontal irradiation and a supplementary photovoltaic derating factor model is proposed for use in tropical SIDS. In addition, the bias of a modelled irradiation dataset was quantified with limited solar radiation data for a tropical Caribbean SIDS, Trinidad and Tobago. For this SIDS, the tool estimates the annual energy output of a 50 MW photovoltaic system to be 57,890 MWh and the levelized cost of electricity to be USD 0.12/kWh. The performance of the proposed tool was comparable with two existing prefeasibility models, RETScreen and SAM, which use past ground measurements and modelled data, respectively. The biases in the annual irradiation data for RETScreen and SAM were determined to be 6% and 25%, respectively, against the solar irradiance dataset used. The proposed tool may be useful for first approximation prefeasibility photovoltaic studies in similar regions with limited climatic data.
... It has been shown in paper [11] that the average value of the performance ratio of 993 residential PV systems in Belgium was found to be 78%. In Island, the performance ratio (PR) of a photovoltaic park, with a peak power of 171.36 kWp, ranged from 58 to 73%, giving an annual PR of 67.36% [12]. ...
In this work, a performance study of a grid-connected PV station under Fkih Ben Salah weather conditions was conducted using PVsyst software. The studied PV system is consisted of polycrystalline silicon (Pc-Si) solar cell technology. The results show that the total annual energy injected into grid was found to be around 779.8 MWh. The performance analysis depicted an annual average value of PR ratio with this technology of nearly 85.2%.KeywordsPV systemPc-SiPerformance analysisPVSyst
The growth of photovoltaic (PV) in developing countries remains a major challenge due to a lack of clarity on the performance of the grid-connected PV system. This paper illustrates some of the key features of the operating performance of the 81.9 kWp PV system installed on the roof of academic buildings. Real-time data was monitored over 12 months to evaluate the performance ratio, energy yield, efficiency, and losses associated with the system. The performance evaluation was done by PVsyst and was validated using the experimental data generated from the PV grid-connected system. The experimental result shows that the maximum final yield of 4.5 kWh/kW/day was obtained during April and the minimum of 2.4 kWh/kW/day was obtained during November. The annual average array and system efficiency was 13.1 % and 12.8 %, with July reported maximum efficiency of 13.4 % and 13.1 % respectively. The effect of high temperature and solar irradiance was observed in May, resulting in the lowest array efficiency of 12.6 %. System performance is seen to have seasonal implications, this was verified through simulation studies, and it was found that to overcome energy shortages, especially during winter seasons, PVsyst analysis predicts such shortcomings more accurately.
The IoT services composition is a complex task, where the necessary services choice and the handsets in the proper order as an integrated composite service is the main challenge in a highly constrained environment. The services composition has been the subject of research in several academic works where the authors try to find the best way to combine and compose the services in an optimal way. In this paper we examine the composition mechanism of IoT services, by focusing on QoS-aware approaches, by a comparative study of some proposed approaches in the literature.KeywordsServices compositionIoTInternet of ThingsQuality of serviceQoS
Current Security Information and Event Management (SIEM) systems use traditional information retrieval methods that produce heavy processing power, and then allocate their local resources to normalize collected logs for advanced correlation. Recently, a Mobile Agent-based SIEM was introduced that uses mobile agents for event collection and normalization at the source device in near real time. In this work, we introduce parallelization to MA-SIEM by comparing two approaches of normalization, the first approach is the multi-thread approach that is used by current SIEM systems, and the second one is the multi-agent approach that is used by MA-SIEM. Our results showed a promising performance gain if we combine both normalization approaches.KeywordsSIEMNormalizationMobile agentsMulti-threading
Photovoltaics (PVs) hold the promise of sustainable electricity production. However, PV output is significantly influenced by variations in terrestrial solar radiation and other weather factors, causing problems in unit commitment, economic power dispatch and reliable electricity distribution from grid-connected, hybrid and off-grid PV plants. Thus, accurate and consistent PV output prediction is crucial for utilities companies and researchers. Current initiatives enlist a plethora of forecasting techniques, including: statistical models, physical models, artificial neural networks and deep learning algorithms. Nevertheless, most of these approaches suffer from computational costs, complex models and uncertainties. Hence, this research employed an ensemble-based Long Short-Term Memory (LSTM) algorithm comprising 10 component LSTM models. The method compares the effects of different data segmentations (three-months to one-day) and is based on varying time-horizons (14-days to 5-mins) in order to compare the effects of seasonal and periodic variations on time-series data and PV output forecast. The comparison is then used to minimise uncertainty by implementing grid search technique. Subsequently, the model’s performance was evaluated using MAPE analysis for two cases involving erratic weather conditions and PV output in two specific days of the year 2020. From the evaluation, the best prediction was found to be for the two-week dataset with MAPE of 6.02. This approach combined with online data acquisition from the Yulara Solar System power plant in central Australia leads to a more practical, computationally economical and robust PV power generation forecasting technique.
Operators of photovoltaic (PV) systems, especially the small ones, monitor only the produced energy output, since they are not equipped with a meteorological station, or there is none in the neighbourhood. When evaluating a large number of PV systems across a region or country, access to the data due to privacy restrictions is usually very limited. To resolve both aspects, we report on a methodology to evaluate the performance of photovoltaic systems where only produced energy data and rated power of the PV system are available and all other data, including orientation and inclination angles, and the exact location are missing. We developed a novel algorithm for automatic detection of orientation/inclination angles and used the recently developed Typical Daily Profiles (TDP) methodology for a fast and accurate evaluation of PV systems. TDPs are representative hourly profiles of the observed parameter (e.g., power, irradiance and temperature) on a monthly basis. For the PV system degradation rate extraction, year-to-year TDPs are used. The case study of 957 PV systems in Slovenia in the period 2015-2019 reveals an average PV system performance ratio exceeding 85% and an average PV system rated power degradation rate of − 0.7% per year.
(In English Below)
Obtener un sistema energético que contribuya a asegurar la estabilidad climática del planeta es uno de los desafíos más importantes de la primera mitad del siglo XXI. Con el propósito de contribuir en la búsqueda de vías que permitan superar la crisis climática global, pero desde acciones locales, y apelando a que la tecnología fotovoltaica (FV) cuenta con excelentes características para habilitar la transición energética que se necesita, esta tesis doctoral tiene como principal objetivo analizar, desde un enfoque global y local, el rol que la energía solar FV descentralizada podría jugar en la transición energética sostenible de un país y territorio específico. Para esto, se emplea como caso de estudio a Chile y particularmente, una de las regiones que lo conforma: la región de Aysén. Tanto Chile como la región de Aysén tienen aspectos que son un reflejo de la crisis global del Antropoceno, pero también cuentan con una gran oportunidad para implementar soluciones ejemplares basadas en sus enormes potenciales de energía renovable (ER). Para realizar dicho análisis se han considerado todos los sectores consumidores de energía y se utilizó una herramienta desarrollada por la Lappeenranta University of Technology (LUT), con la que se modelaron escenarios de transición energética hacia un sistema 100 % basado en ER para Chile, desde un enfoque global y local, donde, en el enfoque local se incluyó a la región de Aysén.
Los resultados revelan que, tanto en Chile como en la región de Aysén, lograr un sistema energético 100% renovable para el año 2050 es técnicamente factible y económicamente viable. En ese año, dependiendo del enfoque y escala territorial, la contribución a la generación eléctrica por parte de la tecnología FV en su conjunto varía entre 39–86 % y, la contribución de la FV descentralizada varía entre 9–12 %; no obstante, la FV descentralizada aporta entre un 27–52 % de la electricidad final que es mayormente consumida en las ciudades por los sectores eléctrico, térmico y transporte. A su vez, la energía solar FV descentralizada crearía en Chile entre el 9–15 % de los empleos anuales directos durante el periodo de transición. Es decir, entre los años 2020 y 2050, el sector de la FV descentralizada crearía 174.274 empleos directos. Además, los resultados también revelan que Chile puede alcanzar la neutralidad en emisiones de carbono en el año 2030 y, se puede convertir en un país emisor negativo de gases de efecto invernadero a partir del año 2035. Todo esto sería posible utilizando menos del 10 % del potencial tecno-económico de ER disponible en este país.
Tras los resultados del trabajo de investigación realizado en esta tesis doctoral, se concluye que la energía solar FV es un elemento vital en la transición energética sostenible, así como también, alcanzar un sistema energético totalmente desfosilizado es más importante que lograr la neutralidad en las emisiones de carbono. Esto último se debe a que una transición a nivel país hacia un sistema energético 100 % renovable implicaría beneficios socio-ambientales y socioeconómicos locales, con impactos globales positivos que se necesitan con urgencia. Si Chile implementara una vía de transición hacia un sistema energético 100 % renovable, no solo podría convertirse en un caso ejemplar en el avance hacia una economía post-combustibles fósiles, si no que también podría contribuir a la transición energética global: a través de la extracción limpia de materias primas clave (como lo son el cobre y el litio), y a través de la producción de combustibles y químicos basados en ER. En resumen, la tecnología FV puede contribuir en la mitigación del cambio climático y la reducción de los niveles de contaminación del aire en las ciudades, al tiempo que impulsa el crecimiento económico local; todo esto, de una manera más descentralizada y participativa.
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Obtaining an energy system that will help to ensure the climactic stability of the planet is one of the most important challenges of the first half of the 21st century. In order to contribute to the search for ways to overcome the global climate crisis, from local activities, and appealing to the fact that photovoltaic (PV) technology has excellent characteristics which could enable the energy transition that is needed, this doctoral thesis has as its main objective the analysis, from a global and local approach, the role that decentralized solar PV could play in the sustainable energy transition of a specific country and territory. For this purpose, Chile and one of its regions (the Aysén region) are used as a case study. Both Chile and the Aysén region have aspects that reflect the global crisis of the Anthropocene, but they also present a great opportunity to implement exemplary solutions, based on their enormous renewable energy (RE) potentials. To carry out this analysis, all energy-consuming sectors were considered. A tool developed by the Lappeenranta University of Technology (LUT) was used, with which energy transition scenarios were modelled towards a 100% RE-based system for Chile, from a global and local approach. The Aysén region was included in the local approach.
The results reveal that, both in Chile and in the Aysén region, achieving a 100% RE system by 2050 is technically feasible and economically viable. In that year, depending on the approach and territorial scale, the contribution to electricity generation by PV technology as a whole would vary between 39–86%. The contribution of decentralized PV would be between 9–12%. However, decentralized PV would contribute 27–52% of the final electricity that is mostly consumed in cities by the power, heat and transport sectors. In turn, decentralized solar PV would create between 9–15% of annual direct jobs in Chile during the transition period. In other words, between 2020 and 2050, the decentralized PV sector would create 174,274 direct jobs. In addition, the results also reveal that Chile could achieve carbon neutrality in 2030 and could become a negative greenhouse gas emitter by 2035. All of this would be possible by using less than 10% of the techno-economic potential of RE available in this country.
From the results of the research work carried out in this doctoral thesis, it is concluded that solar PV is a vital element in the sustainable energy transition. We also find that achieving a fully defossilized energy system is more important than achieving carbon neutrality. The latter is due to the fact that a transition at the country level towards a 100% RE system would imply local socio-environmental and socio-economic benefits, with positive urgently needed global impacts. If Chile implements a transition path towards a 100% RE system, it could not only become an exemplary case in moving towards a post-fossil fuel economy, but could also contribute to the global energy transition through the clean extraction of key raw materials (such as copper and lithium), and through the production of RE-based fuels and chemicals. In summary, PV technology can contribute to mitigating climate change and reducing air pollution levels in cities, while boosting local economic growth, doing all of this in a more decentralized and participatory way.
This paper presents a simple mathematical model to estimate shading losses on PV arrays. The model is applied directly to power calculations, without the need to consider the whole current–voltage curve. This allows the model to be used with common yield estimation software. The model takes into account both the shaded fraction of the array area and the number of blocks (a group of solar cells protected by a bypass diode) affected by shade. The results of an experimental testing campaign on several shaded PV arrays to check the validity of model are also reported.
The objective of this work is to obtain a universal model for calculating the annual angular reflection losses (AAL) of PV modules working in real conditions, useful in the prediction or assessment of the annual performance of PV systems. Instantaneous angular losses (AL) can be calculated by using an analytical model, formerly developed by the authors, that has proved to be in good agreement with the experimental data. In this paper we have used this model to calculate AAL in an hourly basis at 79 different sites all over the world and considering ten different tilt angles, from horizontal to vertical, for south (north) oriented PV modules at north (south) hemisphere sites. From the analysis of the results, we propose an easy-to-use mathematical expression for the calculation of AAL. The model has three different versions that are to be used depending on the availability of the local radiation data. The most detailed expression of the model fits with high degree of accuracy the local AAL data, the second version consists of a global term plus a local weather-descriptive one, and the third version is a universal global model dependent only on the latitude and the PV module tilt angle. Copyright © 2004 John Wiley & Sons, Ltd.
Various practical approaches to calculating the solar irradiation for an inclined surface are reviewed. All assume that the direct and diffuse irradiation for an inclined surface are available, either as measured or calculated values. The paper distinguishes numerous categories of model on the basis of time scale of applicability (hourly or daily or longer time intervals) and on the basis of the radiant flux that is modelled (direct, diffuse or reflected irradiation). The relative performance of the various models is assessed using the results of several studies. Superior models are identified.
Within the German 1000 roof PV programme, about 2000 grid connected PV plants (1–5kWp) with a total peak power of 5 MWp were installed on the roofs of single and two family houses. In the Federal State of Lower Saxony, ISFH has been responsible for the technical inspections and the global monitoring of 172 PV plants up until now. The annual final yields range between 430 kWh/(kWp∗a) and 875 kWh/(kWp∗a) with a mean value of 680 kWh/kWp∗a). Using the annual in-plane irradiation, we determine annual performance ratios in the range 47.5%–81% (mean 66.5%). A procedure to receive standardized performance ratios is introduced using actual peak powers of the PV modules and inverter-specific efficiencies. Typical curves of monthly values of the performance ratio are recorded. PV plants with low final yields are analyzed with respect to operational failures, partly shadowing effects, and poorness in maximum power point adaptation of some inverters. Optimization potentials are also discussed.
This paper presents the Quality Control method for PV modules developed by the Instituto de Energía Solar (IES), an institution with almost 10 years of experience in the field of Quality Control of PV modules associated with supply procedures of PV projects. The method is easy and fast to implement. It consists of Technical and Contractual procedures, both closely related. Concerning the first procedure, detailed description is offered of the type of measurements performed, equipments used, data processing and steadiness control of the method. Regarding the Contractual procedure, after its detailed description an example coming from the Toledo PV plant is offered and commented. The paper then summarises the IES experience on Quality Control processes, together with additional information about time requirements and costs of the IES method. In addition, some reflections upon the possible adoption of the method by countries involved in PV Rural Electrification programmes are finally included. Copyright © 1999 John Wiley & Sons, Ltd.
The Commission of the European Communities PV Demonstration and THERMIE programmes have been managed by DG XVII, the Directorate General for Energy, since 1979. Within the programmes 125 projects, with an installed capacity of over 4.2 MWp, have been undertaken, covering applications ranging from rural electrification, to professional telecommunications and monitoring systems, to grid connected power generation.All the projects are monitored either with analytical monitoring or the simpler global monitoring. The monitoring data is sent regularly to the CEC Joint Research Centre (JRC) at Ispra in Italy for analysis. A wealth of data is now available on the performance of the systems and components. This paper examines the overall performance of different types of PV systems in terms of their energy output and examines the energy losses that can be expected in the main system components: arrays, batteries and inverters.