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  • 1.
    Afzali Gorouh, Hossein
    et al.
    Shahid Bahonar University of Kerman, Iran.
    Salmanzadeh, Mazyar
    Shahid Bahonar University of Kerman, Iran.
    Nasseriyan, Pouriya
    Shahid Bahonar University of Kerman, Iran.
    Hayati, Abolfazl
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Cabral, Diogo
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Karlsson, Björn
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Thermal modelling and experimental evaluation of a novel concentrating photovoltaic thermal collector (CPVT) with parabolic concentrator2022In: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 181, p. 535-553Article in journal (Refereed)
    Abstract [en]

    In the present study, a zero-dimensional thermal model has been developed to analyze a novel low concentration photovoltaic-thermal (CPVT) collector. The model has been developed by driving heat transfer and energy balance equations for each part of the collector and then solving all the equations simultaneously. Moreover, a Monte-Carlo ray-tracing software has been used for optical stimulations of the parabolic trough solar collector. The novel CPVT collector has been experimentally tested at Gävle University (Sweden) and the model has been validated against the experimental results. The primary energy saving equivalent to the thermal-electrical power cogeneration of the CPVT collector has been determined. The effect of glass cover removal, heat transfer fluid (HTF) inlet temperature and mass flow rate on the collector performance has been investigated. The optimum HTF mass flow rates of the collector for maximum electrical yield and overall primary energy saving were determined under specified operating conditions by considering the pump consumption. The effect of mean fluid temperature on the thermal and electrical efficiencies has been studied and the characteristic equation of the thermal efficiency has been obtained. The thermal and electrical peak efficiencies of the collector have been found to be 69.6% and 6.1%, respectively.

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  • 2. Bernardo, Ricardo
    et al.
    Davidsson, Henrik
    Gentile, Niko
    Gomes, João
    Solarus Sunpower AB.
    Gruffman, Christian
    Chea, Luis
    Chabu, Mumba
    Karlsson, Björn
    Mälardalens högskola.
    Measurements of the Electrical Incidence Angle Modifiers of an Asymmetrical Photovoltaic/Thermal Compound Parabolic Concentrating-Collector2013In: Engineering, ISSN 1947-3931, E-ISSN 1947-394X, Vol. 5, p. 37-43Article in journal (Refereed)
    Abstract [en]

    Reflector edges, sharp acceptance angles and by-pass diodes introduce large variations in the electrical performance of asymmetrical concentrating photovoltaic/thermal modules over a short incidence angle interval. It is therefore important to quantify these impacts precisely. The impact on the electrical performance of the optical properties of an asymmet-rical photovoltaic/thermal CPC-collector was measured in Maputo, Mozambique. The measurements were carried out with the focus on attaining a high resolution incidence angle modifier in both the longitudinal and transversal directions, since large variations were expected over small angle intervals. A detailed analysis of the contribution of the diffuse radiation to the total output was also carried out. The solar cells have an electrical efficiency of 18% while the maxi-mum measured electrical efficiency of the collector was 13.9 % per active glazed area and 20.9 % per active cell area, at 25 °C. Such data make it possible to quantify not only the electrical performance for different climatic and operating conditions but also to determine potential improvements to the collector design. The electrical output can be increased by a number of different measures, e.g. removing the outermost cells, turning the edge cells 90°, dividing each receiver side into three or four parts and directing the tracking, when used, along a north-south axis.

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  • 3.
    Cabral, Diogo
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Costeira, João
    Department of Earth Sciences, University of Minho, Portugal.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Electrical and thermal performance evaluation of a district heating system composed of asymmetric low concentration PVT solar collector prototypes2018In: PROCEEDINGS OF THE ISES EUROSUN 2018 CONFERENCE - 12TH INTERNATIONAL CONFERENCE ON SOLAR ENERGY FOR BUILDINGS AND INDUSTRY / [ed] Haberle, A., INTL SOLAR ENERGY SOC , 2018, p. 755-763Conference paper (Refereed)
    Abstract [en]

    Photovoltaic-Thermal (PVT) solar collectors generate electricity and heat from the same gross area. The annual electrical and thermal yields of these systems are dependent on the PVT collector technology, as well as the climate and the type of solar thermal system implemented. This review presents an evaluation of a district heating system composed of 20 asymmetric hybrid low concentrator PVT (C-PVT) solar collector prototypes. The system is installed in a South wall facade in order to maximise the available space (with a tilt of 20 degrees and an orientation of 5 degrees W). The thermal system is connected to the district heating network, thus heating the University buildings. On the other hand, the electrical system is grid-connected, where it feeds the grid directly. Real measurement data has been collected and compared with a thermal (through ScenoCalc tool) and electrical performance models. The annual thermal and electrical yield achieved 86% and 89% of the simulated thermal and electrical yield, respectively.

  • 4.
    Cabral, Diogo
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. Solarus Sunpower Sweden AB, Gävle, Sweden.
    Dostie-Guindon, Paul-Antoine
    Ecole Polytechnique Montréal, Montréal, Canada.
    Karlsson, Björn O.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Ray tracing simulations of a novel low concentrator PVT solar collector for low latitudes2017In: ISES Solar World Congress 2017 - IEA SHC International Conference on Solar Heating and Cooling for Buildings and Industry 2017, Proceedings, International Solar Energy Society , 2017, p. 1068-1079Conference paper (Refereed)
    Abstract [en]

    One way to reduce solar collector's production costs is to use concentrators that increase the output per photovoltaic cell. Concentrating collectors re-direct solar radiation that passes through an aperture into an absorber. The current study evaluates electrical performance of symmetric C-PVT solar collectors with a vertical bifacial receiver, through a numerical ray tracing model software, Tonatiuh. Several designs have been analysed, such as the Pure Parabola (PP) and MaReCo CPC geometries, both symmetric. Parameters such as concentration factor, electrical performance, transversal and longitudinal IAM (Incidence Angle Modifier), the influence of optical elements and influence of the length of the reflector in the shadow effect have been studied for different geometries. The simulations were performed for Mogadishu, Somalia and showed good results for the Pure Parabola collector (PPc) annual received energy, 379 and 317 kWh/m2/year for a focal length of 15 e 30 mm, respectively. A symmetrical double MaReCo CPC collector has been simulated with the annual received energy of 315 kWh/m2/year. The addition of the optical elements will decrease the annual received energy of the PPc by around 11.5%, where the optical properties (7.1%) and glass (4.1%) have the biggest impact in the annual received energy. Overall, symmetric geometries proved to be the most suitable geometries for low latitudes applications, being the geometry f1 (focal length of 15 mm) the best one. 

  • 5.
    Cabral, Diogo
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology. MG Sustainable Engineering AB.
    Hayati, Abolfazl
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Karlsson, Björn O.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Experimental investigation of a CPVT collector coupled with a wedge PVT receiver2021In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 215, p. 335-345Article in journal (Refereed)
    Abstract [en]

    This paper presents an experimental investigation of a photovoltaic-thermal solar collector (commonly known as PVT) that generates both electricity and heat from the same gross area. PVT solar collectors, in theory, achieve higher combined electrical and heat yields. Additionally, PVT enables a thermal coupling between PV cells and a heat transfer cooling medium. Electrical and thermal outdoor testing measurements have been performed on alow concentration PVT solar collector based on a parabolic reflector geometry with a wedge PVT receiver. Several outdoor experiments have been carried out and presented, such as daily instantaneous electrical and thermal performance efficiency diagrams, as well as optical efficiency charts. Moreover, an electrical IncidenceAngle Modifier (for both transversal and longitudinal directions) assessment has been performed and presented. Furthermore, an overall heat loss coefficient of 4.1 W/m2.◦C has been attained. A measured thermal optical and electrical efficiency of 59% and 8% have been achieved, respectively. Additionally, the placement of the wedge receiver shown to be very sensitive to high incidence angles, as the electrical transversal Incidence AngleModifier factor decreases significantly after reaching its electrical peak efficiency at 10◦.

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  • 6.
    Cabral, Diogo
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Karlsson, Björn O.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Performance Evaluation of Non-Uniform Illumination on a Transverse Bifacial PVT Receiver in Combination with a CPC Geometry2019In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 194, p. 696-708Article in journal (Refereed)
    Abstract [en]

    PVT collectors co-generate electricity and heat from the same gross area, thus achieving higher combined heat and electric yields. A comprehensive evaluation has been carried out on non-uniform solar irradiation profile distributions on four symmetric low concentration CPC PVT (LCPVT) solar collector design concepts. Additionally, an electrical and thermal performance evaluation of symmetric truncated LCPVT solar collectors based on a CPC reflector geometry with a central transverse bifacial PVT receiver has been carried out, through a numerical ray-tracing model software and a multi-paradigm numerical computing environment software. A simplified thermal (quasi-dynamic testing method for liquid heating collectors described in the international standard for solar thermal collectors ISO 9806:2017) and electrical performance models were employed to evaluate the LCPVT design concepts. The evaluation was carried out for heating Domestic Hot Water (DHW) for a Single Family House (SFH) in Fayoum (Egypt), where energy yields between 351 and 391 kWh/m2/year have been achieved. The non-uniform solar irradiation assessment showed that the PV cells are exposed to high levels of radiation due to the specific reflector geometry. Furthermore, the study showed that the CPC geometries are very sensitive to the shading effect, as partial shadowing is substantial for high incidence angles.

  • 7.
    Cabral, Diogo
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Hayati, Abolfazl
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology. MG Sustainable Engineering AB, Uppsala, Sweden.
    Gorouh, Hossein Afzali
    Department of Mechanical Engineering, Shahid Bahonar University of Kerman, Kerman 76175 133, Iran.
    Nasseriyan, Pouriya
    Department of Mechanical Engineering, Shahid Bahonar University of Kerman, Kerman 76175 133, Iran.
    Salmanzadeh, Mazyar
    Department of Mechanical Engineering, Shahid Bahonar University of Kerman, Kerman 76175 133, Iran.
    Experimental Electrical Assessment Evaluation of a Vertical n-PERT Half-Size Bifacial Solar Cell String Receiver on a Parabolic Trough Solar Collector2023In: Energies, E-ISSN 1996-1073, Vol. 16, no 4Article in journal (Refereed)
    Abstract [en]

    A two-trough parabolic-shaped concentrating photovoltaic solar collector with a vertical half-size ‘phosphorus-passivated emitter rear totally diffused’ bifacial cell string receiver was designed and built for household applications, with the aim of smooth the electrical ‘duck curve’. The study consisted in testing the concentrating photovoltaic solar collector outdoors, under real weather conditions, for its daily electrical peak power and efficiency, as well as for its electrical transversal and longitudinal Incidence Angle Modifier direction. The outdoor testing measurements were conducted in a parabolic trough with low concentration coupled with a central vertical half-size ‘phosphorus-passivated emitter rear totally diffused’ bifacial cell string receiver. Furthermore, the electrical transversal Incidence Angle Modifier showed to be very delicate due to the position and outline of the receiver, which led to an electrical peak efficiency close to 10% at ±25° (i.e., for an electrical power output of around 49.3 W/m2). To validate the measured parameters, a ray-tracing software has been used, where the measured Incidence Angle Modifiers have a very good agreement with the simulated Incidence Angle Modifiers (e.g., deviation of <4%). Consequently, the concentrating solar collector met the objective of lowering the Photovoltaic cell stress and high radiation intensity, by shifting the electrical peak power at normal (e.g., at 0°) to higher incidence angles (e.g., ±25°); this aids the electrical demand peak shaving, by having the highest electrical power production displaced from the highest intensity solar radiation during the day.

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  • 8.
    Chacin, Luís
    et al.
    Loughborough University, UK.
    Rangel, Simon
    FEUP, Porto, (Portugal.
    Cabral, Diogo
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Impact study of operating temperatures and cell layout under different concentration factors in a CPC-PV solar collector in combination with a vertical glass receiver composed by bifacial cells2019In: Proceedings of the ISES Solar World Conference 2019 and the IEA SHC Solar Heating and Cooling Conference for Buildings and Industry 2019 / [ed] SWC-SHC, 2019, p. 836-847Conference paper (Refereed)
    Abstract [en]

    Solar Collectors with Compound Parabolic Concentrator (CPC) reflectors redirect solar irradiance into the receiver (placed in optimal position). The concept of such devices is to reduce the installation area and energy costs [1]. This research focuses on the behaviour and efficiency of a stationary CPC-PV solar collector. Each trough of this collector has different concentration factors (1.25 and 1.66) with vertically placed bi-facial cell receivers. An analysis of the electrical efficiency is performed in order to evaluate the viability of a CPC geometry with a vertical bifacial PV receiver. Furthermore, an investigation on bifacial cells performance due to concentration (and consequently increased cell temperature) is carried out. A numerical simulation of the yearly available radiation and the Incident Angle Modifiers (IAM) for each geometry is also conducted. Finally, a comparison between the simulations and the outdoor testing on the prototype collector is detailed. The tests took place in Gävle, Sweden (61º Latitude). The results showed that higher concentration factors led to larger operating temperatures (114ºC for a concentration factor of 1.66 and 96ºC for a concentration factor of 1.25). Although this may compromise the cell performance and shorten the device’s life cycle, it is shown that appropriate ventilation will allow manageable operating temperatures.

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  • 9.
    Contero, Francisco
    et al.
    University of Zaragoza.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Gustafsson, Mattias
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Karlsson, Björn O.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    The impact of shading in the performance of three different solar PV systems2016Conference paper (Refereed)
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  • 10.
    Costeira, João
    et al.
    University of Minho, Portugal.
    Vieira, Manuel
    University of Minho, Portugal.
    Hayati, Abolfazl
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Cabral, Diogo
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Development of a compact and didactic solar energy kit using Arduino2018In: PROCEEDINGS OF THE ISES EUROSUN 2018 CONFERENCE - 12TH INTERNATIONAL CONFERENCE ON SOLAR ENERGY FOR BUILDINGS AND INDUSTRY / [ed] Haberle, A., INTL SOLAR ENERGY SOC , 2018, p. 1663-1667Conference paper (Refereed)
    Abstract [en]

    When the sun rises, so does the key element that will shape the future of the world energy landscape. It is not an understatement to say that the solar energy industry is beginning to lead the path towards a sustainable future for all of us. However, the awareness of the potential of this amazing source of energy must begin from the most basic levels of education all the way to university. The scope of this paper is to display a new compact and didactic solar energy kit with the potential to replace current high cost and complex solar energy kits. These solutions are often too expensive and therefore unavailable for most of Europe’s public schools. As such, an equipment was developed using an open-source platform called Arduino that will enable students to conduct practical experiments in a fast, effective and simple manner and thus allow students to acquire the proper expertise in areas like energy, electronics, and programming.

  • 11. Davidsson, Henrik
    et al.
    Bernardo, Ricardo
    Gomes, João
    Solarus AB.
    Gentile, Niko
    Gruffman, Christian
    Chea, Luis
    Karlsson, Björn
    Mälardalens högskola.
    Construction of laboratories for solar energy research in developing countries2014In: Energy Procedia, ISSN 1876-6102, Vol. 57, p. 982-988Article in journal (Refereed)
    Abstract [en]

    A large number of PV-systems have been installed in developing countries around the world duringnumerous projects. The aim is often to improve the quality of life in rural areas, often lacking electricity.Many of these installations provide important services such as lighting and charging of different devices.However, when the projects are finished, there is a large risk that maintenance is not carried out properlyand that malfunctions are never repaired. This situation can leave an otherwise well functioning systemunusable. A key problem is that there are not enough trained technicians that can maintain and repair thesystem locally. One reason to this is the lack of practical education in many developing countries.Furthermore, the availability of spare parts is essential for the long term effectiveness.During 2011 a group of researchers from Lund University in Sweden built a small scale laboratory inMaputo, Mozambique, together with local researchers. The project was successful and today thelaboratory functions both as a teaching facility and as a measurement station for solar energy research forlicentiates, masters and PhD students.The main goal is now to widen the project in order to incorporate more universities in developingcountries. We are now looking for new interested partners in developing countries that believe that such alaboratory could strengthen their possibility to teach practical work and to perform research at the localuniversity. Partners for planning and executing the project are also needed.

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  • 12.
    Fernandes, C. A. F.
    et al.
    Instituto Superior Técnico, Universidade de Lisboa, Portugal .
    Torres, J. P. N.
    Instituto Superior Técnico, Universidade de Lisboa, Portugal .
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Branco, P. J. C.
    Instituto Superior Técnico, Universidade de Lisboa, Portugal .
    Nashih, S. K.
    Stationary solar concentrating photovoltaic-thermal collector - Cell string layout2016In: Proceedings - 2016 IEEE International Power Electronics and Motion Control Conference, PEMC 2016, IEEE, 2016, p. 1275-1282, article id 7752179Conference paper (Refereed)
    Abstract [en]

    The aim of this work is to design the cell string layout in stationary concentrating photovoltaic (PV) or hybrid systems (PVT) in order to minimize the effects of both the longitudinal and transversal shading inherent to concentrating collectors. In this paper it is determined the best configuration of a PV string of cells, composed by several modules, by using a simple mathematical model based on the current vs. voltage of the PV cell. The model calculates the power vs. voltage curves of different possible configurations, in order to identify the optimal one according to efficiency and reliability. The company SOLARUS manufactures PVT collectors with cell strings of 38 solar cells connected in series. Solar cells in the concentrated side of the collector are shaded due to the presence of the aluminium frame of the PVT collector. The effects of shading and non-uniform illumination are minimized by including bypass diodes. Each string has 4 modules of bridged cells, each one associated to a bypass diode. In this work, different combinations of string cells in the collector receiver have been simulated using the free circuit simulation package from Linear Technology Corporation (LTSPICE). Test results are provided by SOLARUS to validate the proposed approach. A comparative analysis is presented at the end, showing that the simulation model is an important tool to define the module configurations that achieve the best energy efficiencies of the PVT panel. 

  • 13.
    Francisco Contero, Jose
    et al.
    University of Zaragoza.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Gustafsson, Mattias
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Karlsson, Björn O.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    The impact of shading in the performance of three different solar PV systems2017In: PROCEEDINGS OF THE 11TH ISES EUROSUN 2016 CONFERENCE, INTL SOLAR ENERGY SOC , 2017, p. 1168-1179Conference paper (Refereed)
    Abstract [en]

    Partial shading decreases the performance of PV modules due to the series connection between the solar cells. In the recent years, several new technologies have emerged within the photovoltaics field to mitigate the effect of shading in the performance of the PV modules. For an accurate assessment of the performance of these devices, it is required to evaluate them comparatively in different circumstances. Three systems with six series-connected PV modules (each containing 60 cells) have been installed at the University of Gavle. System One comprises a string inverter system with 6 PV modules; System Two features a DC-DC optimizer per panel and a string inverter; System Three incorporates three micro inverters for six modules. A major conclusion of this study was that under partial shading of one (or more) modules both System Two (DC-DC optimizers) and System Three (micro inverters) perform considerably better than System One (string inverter), as long as the Impp of the shadowed module is lower than the Impp of the unshaded string It is also important that the Vmpp in the shaded module is higher than the lowest allowed voltage of the DC-DC optimizer or module inverter. The economic implications of the usage of these devices were also analyzed.

  • 14.
    Furbo, Simon
    et al.
    Technical University of Denmark, Kgs. Lyngby, Denmark.
    Perers, Bengt
    Technical University of Denmark, Kgs. Lyngby, Denmark.
    Dragsted, Janne
    Technical University of Denmark, Kgs. Lyngby, Denmark.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Gomes, Mário
    Polytechnic Institute of Tomar, Portugal.
    Coelho, Paulo
    Polytechnic Institute of Tomar, Portugal.
    Yıldızhan, Hasan
    Adana Alparslan Turkes Science and Technology University, Adana, Turkey.
    Halil Yilmaz, İbrahim
    Adana Alparslan Turkes Science and Technology University, Adana, Turkey.
    Aksay, Bilge
    Adana Alparslan Turkes Science and Technology University, Adana, Turkey.
    Bozkurt, Alper
    Adana Alparslan Turkes Science and Technology University, Adana, Turkey.
    Cabral, Diogo
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Hosouli, Sahand
    MG Sustainable Engineering AB, Uppsala.
    Hayati, Abolfazl
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Kaziukonytė, Jovita
    Panevezys University of Applied Sciences, Panevėžys, Lithuania.
    Sapeliauskas, Evaldas
    Panevezys University of Applied Sciences, Panevėžys, Lithuania.
    Kaliasas, Remigijus
    Panevezys University of Applied Sciences, Panevėžys, Lithuania.
    Best Practices for PVT Technology2021In: SWC2021 Proceedings, ISES , 2021Conference paper (Refereed)
    Abstract [en]

    The PVT technology combines solar PV and solar thermal in the same PVT panel. In this way, both electricity and heat are produced by the PVT panel. Compared to the PV technology and the solar heating technology the PVT technology is in the early market stage with only few small and weak industries active. Best practices for the PVT technology, which is still under rapid development, are summarized. Marketed systems with different PVT panel types, different PVT system types with different components for different applications are considered. The potential advantages for PVT systems and the needs for key actors in order to establish a successful sustainable future PVT market are given. Finally, recommendations for a subsidy scheme for PVT systems are given, so that a PVT market can be developed in parallel with the successful PV market.

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  • 15.
    Gallardo, Felipe
    et al.
    La Sapienza University of Rome.
    Guerreiro, Luis
    University of Évora, Portugal.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Exergoeconomic comparison of conventional molten salts versus calcium based ternary salt as direct HTF-TES in CSP parabolic troughs collectors2019In: Proceedings of the ISES Solar World Congress 2019 and IEA SHC International Conference on Solar Heating and Cooling for Buildings and Industry 2019, International Solar Energy Society , 2019, p. 1150-1157Conference paper (Refereed)
    Abstract [en]

    This paper presents an exergo-economic comparison of a Concentrated Solar Power (CSP) Parabolic Trough Collectors (PTC) loop using two alternative types of molten salts as direct Heat Transfer Fluid (HTF) and Thermal Energy Storage (TES) based on operational simulations. The plant size and configuration are inspired in the PTC loop with molten salts HTF and TES currently under deployment at University of Evora in Portugal while the molten salts assessed are conventional molten salt (Solar Salt) and a Calcium based ternary salt. The objective of this study is to establish a comparison of exergetic performance and cost contribution per component in the plant for the two types of HTF. The applied methodology allows to identify the suitability of use for the studied salts, to detect challenges in terms of cost and performance at component level and to identify the cost composition of the CSP electricity as final product, according to the exergetic efficiency, investment and operational cost per component for each case. 

  • 16. Giovinazzo, Carine
    et al.
    Bonfiglio, Luc
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Karlsson, Björn
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Ray Tracing Modelling of an Asymmetric Concentrating PVT2014In: EuroSun 2014 Proceedings, 2014Conference paper (Refereed)
    Abstract [en]

    Photovoltaic thermal (PVT) collectors are able to produce both heat and electricity from the same area. The studied PVT collector is an asymmetric Compound Parabolic Collector (CPC) which is composed two parts: a quarter of a circle and a parabola. This reflector design belongs to the MaReCo (Maximum Reflector Collector) family. The main advantages of this collector design are the reduction of material cost due to concentration and the increase cell efficiency by reducing its working temperature through active cooling.Tonatiuh is a Monte Carlo ray tracing software that is able to simulate the interaction between the sunlight and a concentrating collector. A script was written to repeat the process and simulate the course of the year. The data was processed using Matlab and the annual received radiation on both receiver sides was obtained.A collector model was drawn in Tonatiuh and its material properties were described. Incremental changes were used both to validate the models results and to assess the impact of each change. The first model had only the reflector geometry and the receiver with perfect properties while the final model had a very accurate description of the studied collector and its properties. The final model performed 21% worse than the initial with ideal properties. Additionally, the homogeneity of the solar radiation on the receiver was analyzed and the 3D effective solar radiation graph was plotted. Finally, it was found that over the year, the receiver under concentration produces 13% more energy than the flat side of the receiver, at the best tilt, for both 0º and 60º of latitudes.

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  • 17.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Assessment of the impact of stagnation temperatures in receiver prototypes of C-PVT collectors2019In: Energies, E-ISSN 1996-1073, Vol. 12, no 15, p. 2967-2967Article in journal (Refereed)
    Abstract [en]

    Concentrating Photovoltaic Thermal (C-PVT) solar collectors produce both thermal and electric power from the same area while concentrating sunlight. This paper studies a C-PVT design where strings of series-connected solar cells are encapsulated with silicone in an aluminium receiver, inside of which the heat transfer fluid flows, and presents an evaluation on structural integrity and performance, after reaching stagnation temperatures. Eight test receivers were made, in which the following properties were varied: Size of the PV cells, type of silicone used to encapsulate the cells, existence of a strain relief between the cells, size of the gap between cells, and type of cell soldering (line or point). The test receivers were placed eight times in an oven for one hour at eight different monitored temperatures. The temperature of the last round was set at 220 °C, which exceeds the highest temperature the panel design reaches. Before and after each round in the oven, the following tests were conducted to the receivers: Electroluminescence (EL) test, IV-curve tracing, diode function, and visual inspection. The test results showed that the receivers made with the transparent silicone and strain relief between cells experienced less microcracks and lower power degradation. No prototype test receiver lost more than 30% of its initial power, despite some receivers displaying a large number of cell cracks. The transparent and more elastic silicone is better at protecting the solar cells from the mechanical stress of thermal expansion than the compared silicone alternative, which was stiffer. As expected, larger cells are more prone to develop microcracks after exposure to thermal stress. Additionally, existing microcracks tend to grow in size relatively fast under thermal stress. EL imaging taken during our experiment leads us to conclude that it is far more likely for existing cracks to expand than for new cracks to appear. [ABSTRACT FROM AUTHOR]

  • 18.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Development of Concentrating Photovoltaic-Thermal Solar Collectors2021Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Fossil fuels have greatly improved human living standards and saved countless lives. However, today, their continued use threatens human survival, as CO2 levels rise at an unprecedented pace to levels never seen during human existenceon earth.

    This thesis aims at gathering knowledge on solar energy in general and photovoltaic thermal (PVT) and concentrating photovoltaic thermal (C-PVT) in particular. This thesis establishes several key research questions for PVTs and C-PVT collectors and attempts to answer them.

    A comprehensive market study of solar thermal (ST), photovoltaic (PV) and PVT was conducted to obtain prices and performance. Simulations of the energy output around the world were conducted. A ratio between ST and PV annual output was defined to serve as a tool for comparison and plotted on a world map.

    A key issue for PVT collectors is how to encapsulate the solar cells in a way that, amongst other things, protects the cell from the thermal expansion of the receiver, has a high transparency, and insulates electrically while at the same time conducts the heat to the receiver. In order to be useful, this analysis must also consider the impacts on the production processes. Several prototypes were constructed, a test methodology was created, and the analysis of the results enabled several conclusions on the validity of the different silicon encapsulations methods.

    This thesis relies heavily on collector testing with 30 different prototypes of C-PVTs being designed and constructed. Most testing was conducted using steady state method but quasi dynamic was also carried out. From this work, several guidelines were created for the design of collectors in terms of reflector geometry, cell size, string configuration, encapsulation method and several other design aspects. These analyses were complemented with thermal simulations (COMSOL & ANSYS), string layout (LT SPICE) and evaluation of existing installations. Two novel design ideas came from this thesis work, which the author will patent in the coming year. Additionally, raytracing work has been conducted and a new reflector geometry more appropriate for C-PVTs has been found to significantly improve the annual performance. Finally, the current and future position of PVTs in the global energy market is discussed.

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  • 19.
    Gomes, João
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Bastos, Sílvio
    Instituto Politécnico de Castelo Branco, Portugal.
    Henriques, Mafalda
    Instituto Politécnico de Castelo Branco, Portugal.
    Diwan, Linkesh
    Olsson, Olle
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. olle@solarus.com.
    Evaluation of the impact of stagnation temperatures in different prototypes of low concentration PVT solar panels2015In: ISES Solar World Congress 2015, Conference Proceedings, 2015, p. 993-1004Conference paper (Refereed)
    Abstract [en]

    Photovoltaic thermal (PVT) solar panels produce both thermal and electric power from the some area. This paper concerns a PVT design where the series connected strings of cells are laminated using silicone to an aluminium receiver where the heat transfer fluid flows. An evaluation of the impact of reaching high temperatures in the cell structural integrity and performance is presented. Eight small test receivers were made in which the following properties were varied: Size of the PV cells, type of silicone used to encapsulate the PV cells, existence of a strain relief between the cells, size of the gap between cells and type of cell soldering (line or point soldering). These test receivers were placed in an oven for one hour, under eight different monitored temperatures. The temperature of the last round was set at 220°C which well exceeds the highest temperature the panel design can reach. Before and after each round in the oven, the following tests were conducted to the receivers: Electroluminescence (EL) test, IV-curve, diode function, and visual inspection. The test results showed that the receivers made with the transparent silicone and strain relief between cells experienced less micro-cracks and lower degradation in maximum power. No prototype test receiver lost more than 30% of its initial power, despite the large cell breakage shown in some receivers. Prototype receivers with transparent (softer) silicone showed much far less cracks and power decrease when compared to red (harder) silicone receivers. As expected, larger cells are more prone to develop micro-cracks after exposure to thermal stress. Additionally, existing micro-cracks tend to grow in size into larger micro-cracks relatively fast with thermal stress. The EL imaging taken during our experiment leads us to observe that it seems far easier for existing cracks to expand than for new cracks to appear.

  • 20.
    Gomes, João
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Cabral, Diogo
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Karlsson, Björn O.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Defining an Annual Energy Output Ratio between Solar Thermal Collectors and Photovoltaic Modules2022In: Energies, E-ISSN 1996-1073, Vol. 15, no 15, article id 5577Article in journal (Refereed)
    Abstract [en]

    Photovoltaics (PV) and Solar Thermal (ST) collectors are sometimes competitors, as investment capacity, energy demand, and roof space are limited. Therefore, a ratio that quantifies the difference in annual energy output between ST and PV for different locations is useful. A market survey assessing the average price and performance both in 2013 and 2021 was conducted, showing a factor of 3 cell price decrease combined with a 20% efficiency increase, while ST showed negligible variation. Winsun simulations were conducted, and the results were plotted on the world map. Despite variations due to local climate, the ratio of energy production (ST/PV) increases at lower latitudes mainly due to (a) higher air temperature increasing ST output but decreasing the PV output; (b) solar radiation reducing ST efficiency to zero while having a minor impact on PV efficiency. The ratio was calculated for several ST operating temperatures. For latitudes lower than 66 degrees, the ratio of a flat plate at 50 degrees C to a PV module ranges from 1.85 to 4.46, while the ratio between a vacuum tube at 50 degrees C and a PV module ranges from 3.05 to 4.76. This ratio can support the decision between installing ST or PV while combining different factors such as energy value, system complexity, and installation cost.

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  • 21.
    Gomes, João
    et al.
    Solarus Sunpower AB.
    Davidsson, Henrik
    Gruffman, Christian
    Maston, Stefan
    Karlsson, Björn
    Mälardalens högskola.
    Testing bifacial PV cells in symmetric and asymmetric concentrating CPC collectors2013In: Engineering, ISSN 1947-3931, E-ISSN 1947-394X, Vol. 5, p. 185-190Article in journal (Refereed)
    Abstract [en]

    Bifacial PV cells have the capacity to produce solar electricity from both sides and, thus, amongst other advantages, allow a significantly increase both in peak and annual power output while utilizing the same amount of silicone. Ac-cording to the manufacturer, the bifacial cells are around 1.3 times more expensive than the single-sided cells. This way, bifacial PV cells can effectively reduce the cost of solar power for certain applications.Today, the most common application for these cells is in stationary vertical collectors which are exposed to sunlight from both sides, as the relative position of the sun changes throughout the day. Another possible application is to utilize these cells in concentrating collectors. Three test prototypes utilizing bifacial PV cells were built. The initial two proto-types were built for indoor testing and differed only in geometry of the reflector, one being asymmetric and the other symmetric. Both prototypes were evaluated in an indoor solar simulator. Both reflector designs yielded positive electri-cal performance results and similar efficiencies from both sides of the cell were achieved. However, lower fill factor than expected was achieved for both designs when compared to the single cell tests. The results are discussed and sug-gestions for further testing are presented. A third prototype was built in order to perform outdoor evaluations. This pro-totype utilized a bifacial PV cells string laminated in silicone enclosed between 2 standard glass panes and a collector box with an asymmetric CPC concentrator. The prototype peak electrical efficiency and temperature dependence were evaluated. A comparison between the performance of the bottom and top sides of the asymmetric collector is also pre-sented. Additionally, the incidence modifier angle (IAM) is also briefly discussed.

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  • 22.
    Gomes, João
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Diwan, Linkesh
    Instituto Superior Tecnico, Av. Rovisco Pais, Lisboa, Portugal .
    Bernardo, Ricardo
    Energy and Building Design, Lund University, Lund, Sweden .
    Karlsson, Björn
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Minimizing the impact of shading at oblique solar angles in a fully enclosed asymmetric concentrating PVT collector2014In: Energy Procedia, ISSN 1876-6102, Vol. 57, p. 2176-2185Article in journal (Refereed)
    Abstract [en]

    PVT collectors produce both electricity and heat from the same area. PVT collectors with low concentration factor allow both stationary and tracking configurations. For stationary or single axis tracking, the daily variation in the solar incidence angle can cause significant shading in concentrating collectors. Shading has a larger impact on PV than on thermal collectors and thus the evaluations was more focused on the electrical part. Several prototype versions of a novel design for a concentrating asymmetric PVT collector have been tested and compared. One tested improvement was replacing the reflective end gables with transparent end gables. Another improvement was to use different cell sizes. These actions were expected to minimize the impact of the shading at oblique solar incidence angles. The second action was found to be more beneficial than the first. Measurements were also performed in the solar simulator to fully understand the impact of shading in cell strings with 1/6 the size of standard cells. The latest version of the PVT was found to have, at 25 °C and 1000w/m2, a collector efficiency of 13,7%, a cell area efficiency of 20,3% and an electrical power output of 237W. Lower side of the receiver was producing 58% of the total power.

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  • 23.
    Gomes, João
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Luc, B.
    Ecole Polytechnique Universitaire de Montpellier, France .
    Carine, G.
    Ecole Polytechnique Universitaire de Montpellier, France .
    Fernandes, C. A. F.
    Instituto Superior Técnico, Universidade de Lisboa, Portugal .
    Torres, J. P. N.
    Instituto Superior Técnico, Universidade de Lisboa, Portugal .
    Olsson, Olle
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Costa Branco, P. J.
    Instituto Superior Técnico, Universidade de Lisboa, Portugal .
    Nashih, S. K.
    Analysis of different C-PVT reflector geometries2016In: Proceedings - 2016 IEEE International Power Electronics and Motion Control Conference, PEMC 2016, IEEE, 2016, p. 1248-1255, article id 7752175Conference paper (Refereed)
    Abstract [en]

    One of the main advantages of solar concentrating photovoltaic-thermal collectors (C-PVT) is that these systems are all-in-one module type. For this reason, they are associated to less area and material requirements. Nevertheless, these systems require a more complex analysis in order to improve their performances, since the two types of energy conversion are related to the different demands and their cross effects. In the overall analysis, the collector geometry and the used materials for all their components will be crucial to ensure the system reliability. This study presents preliminary work about re-designing the reflector of C-PVT collectors currently produced in the Swedish SME Solarus Sunpower AB with a comparative analysis on an annual basis of the solar radiation that reaches the collector. For the work accomplished, an open-source advanced object-oriented Monte Carlo ray tracing program (Tonatiuh) is used. For low latitudes, two reflector shapes have been selected since they ensure better performances than the current Solarus reflector. These two new designs achieve both the performance and cost-effectiveness objectives: for the same aperture area and for a thinner box, the collector is 7% to 10% more effective and 18% cheaper.

  • 24.
    Hosouli, Sahand
    et al.
    Kingston University, London, UK; MG Sustainable Engineering AB, Uppsala, Sweden.
    Bagde, Siddhi
    MG Sustainable Engineering AB, Uppsala, Sweden.
    Talha Jahangir, Muhammad
    MG Sustainable Engineering AB, Uppsala, Sweden.
    Hasnain Qamar, Shabahat
    MG Sustainable Engineering AB, Uppsala, Sweden.
    Formosa, Nathan
    Cranfield University, Cranfield, UK.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Mitigating PV cell cracking in solar photovoltaic thermal collectors with a novel H-pattern absorber design2024In: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 242, article id 122516Article in journal (Refereed)
    Abstract [en]

    This paper introduces a novel absorber design for a Solar Photovoltaic Thermal (PVT) collector, specifically addressing the persistent issue of cell cracking induced by thermal expansion. Despite considerable research efforts to advance PVT technology, cell cracking remains a critical challenge, contributing to decreased collector efficiency. In contrast to previous studies, this research adopts a unique approach. A novel PVT design is proposed, featuring an aluminium alloy structure with a distinctive 'H'-shaped pattern of expansion cavities positioned between Photovoltaic (PV) cells and the absorber. This innovative design is engineered to mitigate thermal expansion and optimize the overall performance of the collector.

    A 3-D Computational Fluid Dynamic model, simulated using ANSYS software, validates the proposed PVT design against experimental data from a reference collector. A parametric study explores various H-pattern cavity dimensions, revealing that the 2 mm H-pattern plate cavity design achieves the lowest directional expansion, minimizing the risk of breakage. Results show that the proposed design outperforms the reference collector by 10 %, 2 %, and 8 % in thermal, electrical, and overall efficiency, respectively. Furthermore, the H-pattern design reduces thermal expansion by 20 %, enhancing structural resilience and minimizing the likelihood of PV cell cracking. This study represents a significant advancement in PVT technology, providing a practical and easily implementable solution to the critical issue of cell cracking and presenting an optimal design for real-world applications.

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  • 25.
    Hosouli, Sahand
    et al.
    MG Sustainable Engineering AB, Uppsala.
    Cabral, Diogo
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Kosmadakis, George
    MG Sustainable Engineering AB, Uppsala.
    Mathioulakis, Emmanouil
    National Centre for Scientific Research “Demokritos”, Agia Paraskevi, Greece.
    Mohammadi, Hadi
    MG Sustainable Engineering AB, Uppsala.
    Loris, Alexander
    MG Sustainable Engineering AB, Uppsala.
    Naidoo, Adeel
    MG Sustainable Engineering AB, Uppsala.
    Performance Assessment of Concentrated Photovoltaic Thermal (CPVT) Solar Collector at Different Locations2021In: SWC2021 Proceedings, ISES , 2021Conference paper (Refereed)
    Abstract [en]

    The double MaReCo (symmetric reflector geometry) solar collector (DM-CPVT) has been designed and developed by MG Sustainable Engineering AB (MG) and the University of Gävle (HiG). Performance and overall electrical and thermal parameters of the collector have been studied and presented. The outdoor tests have been performed in both Sweden during the summer months of 2020 and Greece in September of 2020. The goal of the studied designs is to optimize the incoming solar radiation that can be collected without the need for tracking. This is possible due to the use of a symmetric reflector geometry with low concentration factor and lower collector depth. The use of a symmetric reflector geometry allows higher annual outputs worldwide. Furthermore, a low concentration factor is necessary to avoid tracking and a lower collector depth to reduce the shading, which is particularly important for the electrical production of these DM-CPVT design concepts. The testing facilities in both locations are also described in this paper. The information on the thermal performance of a collector is important for the prediction of the energy output of any solar system. The thermal properties assessment of the DM-CPVT collector followed the procedures of the ISO 9806:2017 standard and reported. The outdoor testing results have been validated with a deviation of 2.8% and 2.4% for both thermal and electrical peak efficiencies between the testing facilities, respectively. Regarding the Incidence Angle Modifier testing results, the deviation is negligible for all angles of incidence, which shows that outdoor testing procedures can be fairly accurate when tracking systems are not available. 

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  • 26.
    Hosouli, Sahand
    et al.
    MG Sustainable Engineering AB, Uppsala, Sweden.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Loris, Alexander
    MG Sustainable Engineering AB, Uppsala, Sweden.
    Pazmiño, Ivan-Acosta
    MG Sustainable Engineering AB, Uppsala, Sweden.
    Naidoo, Adeel
    MG Sustainable Engineering AB, Uppsala, Sweden.
    Lennermo, Gunnar
    MG Sustainable Engineering AB, Uppsala, Sweden.
    Mohammadi, Hadi
    MG Sustainable Engineering AB, Uppsala, Sweden.
    Evaluation of a solar photovoltaic thermal (PVT) system in a dairy farm in Germany2023In: Solar Energy Advances, ISSN 2667-1131, Vol. 3, article id 100035Article in journal (Refereed)
    Abstract [en]

    Livestock farms are a major contributor to CO2 emissions. The use of renewable energy sources (RES) is an important step to mitigate emissions from farms. This paper develops and evaluates a market-integrated, cost-effective, and case-sensitive RES solution for livestock farms. For this purpose, the dairy farm at LVAT-ATB in Germany; which includes three barns for milk production with a total area of 3950 m2, was considered. A solar PVT system is designed to most effectively use the heat recovery of the milk coolers and to use the thermal heat from the PVT system to lift the inlet temperature of an electric boiler (E-boiler) and reduce grid electricity consumption. The performance and monthly thermal output of the designed PVT system are evaluated using two different PVT collectors; Solarus (concentrated) and Dual Sun (flat plate). A preliminary analysis was performed to determine the PVT collector most suitable for the livestock farm here studied. The DualSun collector generated a higher electricity output than the Solarus C-PVT, however, the C-PVT was able to reach higher temperatures. Since the LVAT-ATB farm site included an existing heat recovery system, the integration point was carefully defined and a semi-automated system was incorporated to (1) use the heat from the heat recovery system as the inlet heat for the PVT system and (2), to use the PVT buffer tank as additional storage to store excess heat from the heat recovery system. Using this approach, a maximum amount of thermal energy can be stored. The PVT system would further raise the temperature from the heat recovery system and thus minimize the electricity consumption of the E-boiler. Furthermore, a draft layout of all the components and outdoor enclosure was presented. 24 Solarus PVT collectors running at mean temperature of 45 °C meet 16% of the annual hot water demand of the dairy farm by direct solar heat and this number of PVTs can supply up to 38% of hot water demand in summer months. The payback period for this system is less than 6 years and annual electrical energy utilization ratio and highest solar thermal fraction are 9.7 and 51.9%, respectively. Furthermore, 24 PVTs on an annual basis, generate slightly more than 4,200 kWh of electricity that can be used to offset electricity consumed by electric boilers in the LVAT farm.

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  • 27.
    Hosouli, Sahand
    et al.
    MG Sustainable Engineering AB, 75340 Uppsala, Sweden.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology. MG Sustainable Engineering AB, 75340 Uppsala, Sweden;Faculty of Engineering and Sustainable Development, University of Gävle, 80176 Gävle, Sweden.
    Talha Jahangir, Muhammad
    MG Sustainable Engineering AB, 75340 Uppsala, Sweden.
    Pius, George
    Absolicon Solar Collector AB, 87133 Härnösand, Sweden.
    Performance Evaluation of Novel Concentrating Photovoltaic Thermal Solar Collector under Quasi-Dynamic Conditions2023In: Solar, E-ISSN 2673-9941, Vol. 3, no 2, p. 195-212Article in journal (Refereed)
    Abstract [en]

    Concentrating Photovoltaic Thermal (CPVT) collectors are suitable for integration in limited roof space due to their higher solar conversion efficiency. Solar sunlight can be used more effectively by CPVT collectors in comparison to individual solar thermal collectors or PV modules. In this study, the experimental investigation of a novel CPVT collector called a PC (power collector) has been carried out in real outdoor conditions, and the test set-up has been designed based on ISO 9806:2013. A quasi-dynamic testing method has been used because of the advantages that this method can offer for collectors with a unique construction, such as the proposed collector, over the steady-state testing method. With a quasi-dynamic testing method, it is possible to characterize the collector within a wide range of incidence angles and a complex incidence angle modifier profile. The proposed novel collector has a gross area of 2.57 m2. A maximum power output per collector unit area of 1140 W is found at 0 °C reduced temperature (1000 W/m2 irradiance level), while at a higher reduced temperature (70 °C), it drops down to 510 W for the same irradiance level. The data have been fitted through a multiple linear regression method, and the obtained efficiency curve coefficients are 0.39, 0.192, 1.294, 0.023, 0.2, 0, −5929 and 0 for Kθd, b0, c1, c2, c3, c4, c5 and c6, respectively. The experimental characterization carried out on the collector proved that the output powers calculated by using the obtained parameters of the quasi-dynamic testing method are in good agreement with experimental points.

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  • 28.
    Kurdia, Ali
    et al.
    Högskolan Dalarna, Borlänge, Sweden.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Pius, George
    Ollas, Patrik
    RISE Research Institutes of Sweden, Borås, Sweden.
    Olsson, Olle
    Absolicon, Gävle, Sweden.
    Quasi-Dynamic Testing of a Novel Concentrating Photovoltaic Solar Collector According to ISO 9806:20132018In: PROCEEDINGS OF THE ISES EUROSUN 2018 CONFERENCE - 12TH INTERNATIONAL CONFERENCE ON SOLAR ENERGY FOR BUILDINGS AND INDUSTRY / [ed] Haberle, A., INTL SOLAR ENERGY SOC , 2018, p. 1262-1273Conference paper (Refereed)
    Abstract [en]

    Testing and certification of solar thermal collectors has been widely researched and improved over the years, however, many of the developments in the test standards has been focused primarily on generic flat plate collectors. In this study, the focus was on depicting the applicability of the current standard in characterizing the performance of a novel concentrating solar collector of design. The applicability of the Quasi-Dynamic Testing (QDT) method for collector certification, by the ISO 9806:2013, is studied to be used in characterizing the novel concentrating PVT collector, and to point out the weaknesses observed, and essential additions required.

  • 29.
    Lanca, Miguel
    et al.
    Instituto Superior Técnico, Lisbon University, Portugal.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Hayati, Abolfazl
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Numerical Simulation of the Thermal Performance of Four Concentrating Collectors with Bifacial PV Cells2018In: PROCEEDINGS OF THE ISES EUROSUN 2018 CONFERENCE - 12TH INTERNATIONAL CONFERENCE ON SOLAR ENERGY FOR BUILDINGS AND INDUSTRY / [ed] Haberle, A., INTL SOLAR ENERGY SOC , 2018, p. 810-821Conference paper (Refereed)
    Abstract [en]

    Bifacial photovoltaic cells can produce electricity from the incoming solar radiation on both sides. Used in combination with concentrating solar technology, bifacial photovoltaic cells can see its electrical output further augmented, thus decreasing the cost per kWh. It is known, however, that the efficiency reduction when these cells are exposed to increased temperatures is a relevant factor. This can happen, for example, when they are mounted on a glassed collector or receiver. In this study, a thermal analysis is carried out on four prototypes of concentrating collectors with bifacial PV cells. Results show that, as expected, when glass and gables are removed from the collector, much better heat dissipation is achieved, thus resulting in favorable cell operation conditions.

  • 30.
    Lança, Miguel
    et al.
    Instituto Superior Técnico, Lisbon University, Portugal.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology. MG Sustainable Engineering AB, Uppsala, Sweden.
    Cabral, Diogo
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Thermal performance of three concentrating collectors with bifacial photovoltaic cells part I – Experimental and computational fluid dynamics study2024In: Proceedings of the Institution of mechanical engineers. Part A, journal of power and energy, ISSN 0957-6509, E-ISSN 2041-2967, Vol. 238, no 1, p. 140-156Article in journal (Refereed)
    Abstract [en]

    Bifacial photovoltaic cells can produce electricity from incoming solar radiation on both sides. These cells have a strong potential to reduce electricity generation costs and may play an important role in the energy system of the future. However, today, these cells are mostly deployed with one side receiving only ground reflection, which leads to a profound sub-optimal utilization of one of the sides of the bifacial cells. Concentration allows a better usage of the potential of bifacial cells, which can lead to a lower cost per kWh. However, concentration also adds complexity due to the higher temperatures reached which add the requirement of cooling in order to achieve higher outputs. This way, this paper focuses on the effectiveness of forced air circulation methods by comparing the thermal performance of three specific concentrating bi-facial collector designs. This paper developed a computational model, using ANSYS Fluent intending to assess the thermal performance of a covered concentrating collector with bifacial Photovoltaic (PV) cells. These results have then been validated by outdoor measurements. Results show that even a simple natural ventilation mechanism such as removing the side gable can effectively reduce the receiver temperature, thus resulting in favourable cell operation conditions when compared to the case of an airtight collector. Therefore, compared with a standard model, a decrease of 13.5% on the cell operating temperature was reported when the side gables are removed. However, when forced ventilation is apllied a 22.8% reduction on temperature is found compared to the standard air-tight model. The validated CFD model has proven to be a useful and robust tool for the thermal analysis of solar concentrating systems.

  • 31.
    Lança, Miguel
    et al.
    Department of Mechanical Engineering, Instituto Superior Técnico, Lisbon University, Lisboa, Portugal.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology. MG Sustainable Engineering AB, Uppsala, Sweden.
    Cabral, Diogo
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Hosouli, Sahand
    Department of Mechanical Engineering, Kingston University, London, UK.
    Thermal performance of three concentrating collectors with bifacial PV cells. Part II – parametrical study2024In: Proceedings of the Institution of mechanical engineers. Part A, journal of power and energy, ISSN 0957-6509, E-ISSN 2041-2967Article in journal (Refereed)
    Abstract [en]

    One of the problems in using PV cells to extract energy from sunlight is the temperature effect on PV cells. As the solar panel is heated, the conversion efficiency of light to electrical energy is diminished. Moreover, successive temperature elevations can cause dilatations in the array of cells which may also contribute to the degradation of the receiver. Some of the operating temperature mitigation approaches may include air-flow ventilation. In this study, data obtained by experimental and numerical simulations of a collector with bifacial PV cells is compared to the expressions found in the literature for the estimation of the heat transfer coefficient. Forced ventilation was applied to the studied collector as it accounts for much better heat dissipation. A new correlation for the estimation of the heat transfer coefficient is developed for such a geometry, for inlet velocities ranging between 3 and 8 m/s. Values of heat transfer coefficient estimated in the present work have been compared with studies of other researchers.

  • 32.
    Loris, Alexander
    et al.
    MG Sustainable Engineering AB, Uppsala.
    Hosouli, Sahand
    MG Sustainable Engineering AB, Uppsala.
    Lennermo, Gunnar
    MG Sustainable Engineering AB, Uppsala.
    Kulkarni, Manali
    MG Sustainable Engineering AB, Uppsala.
    Poursanidis, Yannis
    MG Sustainable Engineering AB, Uppsala.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Evaluation of the Use of Concentrated Solar Photovoltaic Thermal Collectors (CPVT) in a Dairy and Swine Farm in Europe2021In: SWC2021 Proceedings, ISES , 2021Conference paper (Refereed)
    Abstract [en]

    The use of CPVT collectors in combination with other renwable energy sources (RES) has been evaluated for a dairy and swine farm in view of fossil-free farming practises. Electrical and thermal heat demands have been analysed for the LVAT-ATB dairy farm in Germany, and for the ILVO swine farm in Belgium. A CPVT collector produced by Solarus has been tested and modelled the thermal and electrical performance output for each of the farms. Taking into consideration the demands of the farms, the use of the CPVT in a fossil-free energy system for the farm has been evaluated. Analysis of the swine farm suggested to use the CPVT as a heat source to improve the system efficiency for two heat pumps that would provide the final heating. A similar result was obtained in the dairy farm where the CPVT would raise the temperature of the incoming water to the heat recovery system of the milk cooler.

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  • 33.
    Mantei, Franz
    et al.
    Technische Universität, Berlin, Germany.
    Henriques, Mafalda
    University of Castelo Branco, Portugal.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Olsson, Olle
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system. Solarus Sunpower Sweden AB, Gävle, Sweden.
    Karlsson, Björn
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    The night cooling effect on a C-PVT solar collector2015In: ISES Solar World Congress 2015, Conference Proceedings, International Solar Energy Society, 2015, p. 1167-1175Conference paper (Refereed)
    Abstract [en]

    Night cooling consists in running a fluid through a solar panel during the night in order to reduce the fluid temperature which can be used for cooling applications. Radiative heat losses can allow the fluid to reach temperatures below ambient while conduction and convection works to equalize the collector with the ambient temperature. This paper analyzes the possibility of using an asymmetric concentrating photovoltaic thermal solar collector (C-PVT) for cooling applications during the night by losing heat through convection, conduction and irradiation. The cooling performance of the C-PVT collector has been measured during the night at different inlet temperatures in the interval of 13 to 38°C which corresponded to a AT (between the collector average and the ambient) from 6 to 28°C. The performance of the tested C-PVT collector has been measured at different inlet temperatures in an interval of 13 to 38°C. During all performed measurements, the radiation losses did not drive the collector temperature below ambient temperature. With high AT (between the inlet and the ambient) of 30°C, a 1,85°C temperature decrease in the fluid was obtained. For AT of 14°C, the temperature decrease was only 0,88°C. The measurements showed a night U-value for the Solarus C-PVT of 4,2 W/m2K This correlates well with previous papers showing measurements taken during the day. Heat losses seem to be dominated by convection and conduction due to the existence of the glass in the collector. Despite this, a measurable relation between heat losses and cloudiness factor exists. This shows that the irradiance losses are not negligible. Only very specific applications can be suited for night cooling with this collector design, since it is not so common to have applications that require low grade cooling during the night time or justify storing this energy. However, if the C-PVT design was made without a glass cover, the results could potentially be very different for locations with many clear nights.

  • 34.
    Meramveliotakis, George
    et al.
    National Centre of Scientific Research "Demokritos", Greece.
    Kosmadakis, George
    National Centre of Scientific Research "Demokritos", Greece.
    Krikas, Achileas
    National Centre of Scientific Research "Demokritos", Greece.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Pilou, Marika
    National Centre of Scientific Research "Demokritos", Greece.
    Innovative Coupling of PVT Collectors with Electric-Driven Heat Pumps for Sustainable Buildings2020In: PROCEEDINGS OF THE ISES EUROSUN 2020 CONFERENCE - 13TH INTERNATIONAL CONFERENCE ON SOLAR ENERGY FOR BUILDINGS AND INDUSTRY, 2020, p. 440-451Conference paper (Refereed)
    Abstract [en]

    An innovative renewable- energy based system is examined for covering the heating and cooling demand in residential buildings. This system adopts an alternative solar-assisted heat pump configuration, developed around its two main components: the PVT collectors and a dual-source heat pump. The heat produced by the collectors can be either used directly for covering the heating needs or stored in a buffer tank for supplying the heat pump with low-temperature heat, exploiting all solar heat and operating the heat pump with an elevated performance for a longer period during the day. Once the stored heat in the buffer tank is discharged, the heat pump is supplied by ambient heat. The same configuration can also operate at cooling mode during summer, with the heat pump reversing its operation. The current work examines the main system parameters, in order to evaluate its performance for covering a large share of the building's energy needs.

  • 35.
    Murali, Damu
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Acosta-Pazmiño, Iván P.
    MG Sustainable Engineering AB.
    Loris, Alexander
    MG Sustainable Engineering AB.
    García, Abel Climente
    MG Sustainable Engineering AB.
    Benni, Stefano
    University of Bologna, Italy.
    Tinti, Francesco
    University of Bologna, Italy.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology. MG Sustainable Engineering AB.
    Experimental assessment of a solar photovoltaic-thermal system in a livestock farm in Italy2024In: Solar Energy Advances, ISSN 2667-1131, Vol. 4, article id 100051Article in journal (Refereed)
    Abstract [en]

    This paper presents an experimental evaluation of the performance of a solar photovoltaic-thermal (PVT) system in a swine farm at Mirandola in Italy. In this project named RES4LIVE, funded by the EU’s Horizon 2020 program, a PVT system is installed to replace fossil fuel consumption in one of the barns on the farm. The electrical energy from the collectors is utilized to operate the heat pump and provide electricity to the barn, whereas the thermal energy from the collector is stored in a borehole thermal energy storage (BTES) for further use by a 35 kW heat pump. The hybrid solar field consists of 24 covered PVT flat plate collectors (7.68 kWel and 25 kWth) with a total aperture area of 39.3 m2, which can increase the temperature of the heat transfer fluid (HTF) to up to 40 °C. The PVT system is connected to a modular solar central (SC) with a standardized design that can also be used for other similar applications. The hybrid solar system complemented by energy storage is expected to save approximately 20,850 kg CO2/year . The data collected from the PVT system, SC, and BTES are rigorously analyzed to evaluate its overall performance. A comprehensive performance assessment reveals the capability of the solar system to reduce carbon emissions and effectively replace fossil fuel consumption in the agricultural sector.

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  • 36.
    Nashih, Samuel K.
    et al.
    Instituto de Telecomunicações, Lisboa, Portugal .
    Fernandes, Carlos A. F.
    Instituto de Telecomunicações, Lisboa, Portugal .
    Torres, João Paulo N.
    Instituto de Telecomunicações, Lisboa, Portugal .
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Branco, P. J. Costa
    Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal .
    Validation of a Simulation Model for Analysis of Shading Effects on Photovoltaic Panels2016In: Journal of solar energy engineering, ISSN 0199-6231, E-ISSN 1528-8986, Vol. 138, no 4, article id 044503Article in journal (Refereed)
    Abstract [en]

    Numerical simulation results and modeling on the electrical features of concentrating photovoltaic-thermal (PVT) using the free circuit simulation package from linear technology corporation (LTSPICE) are presented. The effects of partial shading of cell strings and temperature are analyzed, showing very good agreement with the results obtained experimentally in lab, at Lisbon University, and under outdoor testing using similar receivers, at the SME Solarus Sunpower AB, a Swedish company whose mission is the development, production, and marketing of concentrated solar technology to the world market. The potential of the used methodology for the design of the solar cell configuration is emphasized as an important tool to optimize PV and PVT performances in the energy conversion process. 

  • 37.
    Nasseriyan, Pouriya
    et al.
    Shahid Bahonar University of Kerman, Iran.
    Afzali Gorouh, Hossein
    Shahid Bahonar University of Kerman, Iran.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology. MG Sustainable Engineering AB.
    Cabral, Diogo
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Salmanzadeh, Mazyar
    Shahid Bahonar University of Kerman, Iran.
    Lehmann, Tiffany
    Polytech de Montpellier, France.
    Hayati, Abolfazl
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Numerical and Experimental Study of an Asymmetric CPC-PVT Solar Collector2020In: Energies, E-ISSN 1996-1073, Vol. 13, no 7, article id 1669Article in journal (Refereed)
    Abstract [en]

    Photovoltaic (PV) panels and thermal collectors are commonly known as mature technologies to capture solar energy. The efficiency of PV cells decreases as operating cell temperature increases. Photovoltaic Thermal Collectors (PVT) offer a way to mitigate this performance reduction by coupling solar cells with a thermal absorber that can actively remove the excess heat from the solar cells to the Heat Transfer Fluid (HTF). In order for PVT collectors to effectively counter the negative effects of increased operating cell temperature, it is fundamental to have an adequate heat transfer from the cells to the HTF. This paper analyzes the operating temperature of the cells in a low concentrating PVT solar collector, by means of both experimental and Computational Fluid Dynamics (CFD) simulation results on the Solarus asymmetric Compound Parabolic Concentrator (CPC) PowerCollector (PC). The PC solar collector features a Compound Parabolic Concentrator (CPC) reflector geometry called the Maximum Reflector Concentration (MaReCo) geometry. This collector is suited for applications such as Domestic Hot Water (DHW). An experimental setup was installed in the outdoor testing laboratory at G&auml;vle University (Sweden) with the ability to measure ambient, cell and HTF temperature, flow rate and solar radiation. The experimental results were validated by means of an in-house developed CFD model. Based on the validated model, the effect of collector tilt angle, HTF, insulation (on the back side of the reflector), receiver material and front glass on the collector performance were considered. The impact of tilt angle is more pronounced on the thermal production than the electrical one. Furthermore, the HTF recirculation with an average temperature of 35.1C and 2.2 L/min flow rate showed that the electrical yield can increase by 25%. On the other hand, by using insulation, the thermal yield increases up to 3% when working at a temperature of 23 C above ambient.

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  • 38.
    Panchal, Rajan
    et al.
    University of Kassel, Germany.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Cabral, Diogo
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Eleyele, Abideme
    Uppsala University.
    Lança, Miguel
    Instituto Superior Técnico, Lisboa, Portugal.
    Evaluation of Symmetric C-PVT Solar Collector Designs with Vertical Bifacial Receivers2019In: Proceedings of the ISES Solar World Congress 2019 and IEA SHC International Conference on Solar Heating and Cooling for Buildings and Industry 2019, 2019, p. 165-176Conference paper (Refereed)
    Abstract [en]

    Photovoltaic thermal (PVT) solar collectors can be an effective solution for system output improvement. Photovoltaic thermal collectors naturally have a more expensive receiver than simpler photovoltaic or thermal only collectors, therefore making concentration a more appealing solution to achieve cost reduction. However, concentrating systems need careful analysis on the design phase in order to optimize the annual output. In addition, for stationary (non-tracking) collectors, it is critical to determine the incidence angle modifier (IAM).For this reason, a reflector study was carried out to determine suitable reflector designs for a stationary concentrating PVT collector. The reflectors were simulated using a Monte Carlo raytracing software called Tonatiuh. The two selected reflectors designs were named “pure parabola” (PP) and “compound parabolic concentrator” (CPC). The concentration ratio of 1.2 and 1.6 were selected for each reflector designs, which means a total of 4 collector troughs. The next step involved the construction of the two selected C-PVT collector designs, which were built and subsequently tested by the authors. The IAM was assessed and discussed by simulation and outdoor testing in detail.The IAM results show similar decreases in longitudinal IAM for both the PP and the CPC CPVT collector for the 1.2 concentration factor. For the transversal IAM with 1.2 of concentration factor, the CPC over performs. For the 1.6 concentration prototype collectors, the results are fairly similar. Lastly, the annual output was also simulated and presented.

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  • 39.
    Torres, João Paulo N.
    et al.
    Instituto de Telecomunicações, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal.
    Fernandes, Carlos A. F.
    Instituto de Telecomunicações, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Luc, Bonfiglio
    Ecole Polytechnique Universitaire de Montpellier, Montpellier, France.
    Carine, Giovinazzo
    Ecole Polytechnique Universitaire de Montpellier, Montpellier, France.
    Olsson, Olle
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering, Energy system.
    Branco, P. J. Costa
    Associated Laboratory for Energy, Transports and Aeronautics, Institute of Mechanical Engineering (LAETA, IDMEC), Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal.
    Effect of reflector geometry in the annual received radiation of low concentration photovoltaic systems2018In: Energies, E-ISSN 1996-1073, Vol. 11, no 7, article id 1878Article in journal (Refereed)
    Abstract [en]

    Solar concentrator photovoltaic collectors are able to deliver energy at higher temperatures for the same irradiances, since they are related to smaller areas for which heat losses occur. However, to ensure the system reliability, adequate collector geometry and appropriate choice of the materials used in these systems will be crucial. The present work focuses on the re-design of the Concentrating Photovoltaic system (C-PV) collector reflector presently manufactured by the company Solarus, together with an analysis based on the annual assessment of the solar irradiance in the collector. An open-source ray tracing code (Soltrace) is used to accomplish the modelling of optical systems in concentrating solar power applications. Symmetric parabolic reflector configurations are seen to improve the PV system performance when compared to the conventional structures currently used by Solarus. The parabolic geometries, using either symmetrically or asymmetrically placed receivers inside the collector, accomplished both the performance and cost-effectiveness goals: for almost the same area or costs, the new proposals for the PV system may be in some cases 70% more effective as far as energy output is concerned.

  • 40.
    Yildizhan, Hasan
    et al.
    Adana Alparslan Türkeş Science and Technology University, Adana, Turkey.
    Hosouli, Sahand
    Kingston University London, London, United Kingdom; MG Sustainable Engineering AB, Uppsala, Sweden.
    Yılmaz, Sıdıka Ece
    Adana Alparslan Türkeş Science and Technology University, Adana, Turkey.
    Gomes, João
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.
    Pandey, Chandan
    Imperial College London, United Kingdom.
    Alkharusi, Tarik
    University of Technology and Applied Sciences, Muscat, Oman.
    Alternative work arrangements: Individual, organizational and environmental outcomes2023In: Heliyon, E-ISSN 2405-8440, Vol. 9, no 11, article id e21899Article in journal (Refereed)
    Abstract [en]

    Flexible working models are widely used around the world. Furthermore, several countries are currently transitioning to a 4-day workweek. These working models have significant effects on organizational behavior and the environment. The study investigates the employees' attitudes and behaviors toward flexible working and 4-day workweek and the impact on the environment. The semi-structured interview method was used in the study to determine employee attitudes and behaviors; the carbon footprint calculation method was used to determine the environmental impact of a 4-day workweek. According to the study's findings, it has been discovered that there would be a positive impact on socialization, happiness, stress factor, motivation, personal time, mental health, comfort, work-life balance, time-saving, willingness, positive working environment, personal time, and physical health. Furthermore, a 4-day workweek reduced commuting emissions by 20%, resulting in a 6,07 kg tCO2e reduction per person. As a result, the study attempted to draw attention holistically to the positive effects of the flexible working model and 4-day workweek. The study is intended to serve as a tool for decision-makers and human resource managers.

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