The current impetus for alternative energy sources is increasing the demand for solar energy technologies in Florida – the Sunshine State. Florida’s energy production from solar, thermal or photovoltaic sources accounts for only 0.005% of the state total energy generation. The existing types of technologies, methods of installation, and mounting locations for solar panels vary significantly, and are consequently affected by wind loads in different ways. The fact that Florida is frequently under hurricane risk and the lack of information related with design wind loads on solar panels result in a limited use of solar panels for generating energy in the “Sunshine State” Florida. By using Boundary Layer Wind Tunnel testing techniques, the present study evaluates the effects of wind on solar panels, and provides explicit and reliable information on design wind loads in the form of pressure coefficient value. The study considered two different types of solar panel arrangements, (1) isolated solar panel and (2) arrays, and two different mounting locations, (1) ground mounted and (2) roof mounted. Detailed wind load information was produced as part of this study for isolated and arrayed solar panels. Two main conclusions from this study are the following:(1) for isolated solar panel with high slopes the wind load for wind angle of attack (AoA) perpendicular to the main axis exhibited the largest wind loads; (2) for arrays, while the outer rows and column were subjected to high wind loads for AoA perpendicular to the main axis, the interior solar panels were subjected to higher loads for oblique AoA.

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The Swedish Island of Gotland provides an interesting case of how renewable energy technologies can be combined and integrated into the electricity system. The study simulates the load, wind power production and PV power production to estimate the PV power potential for existing buildings on Gotland. The theoretical PV power potential on Gotland is calculated to be 667 MW. The PV power potential is split between 28% for dwelling buildings, 9% for multi-dwelling buildings, 7% for industry and 56% for other buildings. The current limit for wind power on Gotland is 195 MW. With the installed capacity of 194 MW wind power, an additional of 22 MW of PV power is possible to integrate without increasing the hours of overload on the power cable. With the prospected submarine power cable, a total of 529 MW PV power is possible to integrate with the existing 194 MW of wind power.

Solar energy harvesting using photovoltaic (PV) systems has gained popularity in recent years due to its relative ease of use and its cost efficiency compared to the rest of the clean energy sources. However, to further expand the application of PV systems requires making them more desirable than the other competitive energy sources. The improvement of safety and cost efficiency are requisites for further popularization of PV system application. To satisfy these requisites it is necessary to optimally design the system against the environmental conditions. Wind action is one of the main ambient loads affecting the performance of PV systems. This dissertation aims to investigate the effects of wind load on residential scale roof mounted PV panels and their supporting structures as well as evaluating the structural response of the system to the wind-induced vibration. To achieve these goals, several full- and large-scale experimental tests were performed at the Wall of Wind Experimental Facility at Florida International University (FIU). The wind effects on different PV system and roof configurations were investigated in these tests. The results shed light on the most influential parameters affecting the wind pressures acting on the PV panel surface. In addition, the findings are presented in the form of design pressure coefficients for adoption to future building codes and wind standards. The second phase of the physical testing included the investigation of the actual response of the PV system to the wind action. Because of the dynamic properties of the PV panel, it was expected that the wind induced vibration can affect the dynamic response of the system including the acceleration at the panel surface and support reactions at the racking system to roof interface. To test this theory, two different models of the system were developed, one with the real PV panels and the other one with wooden rigid panels. Comparing the results, it was concluded that the dynamic response of the system was not considerably affected by wind-induced fluctuations. Finally, and to better understand the dynamic response of the system, an analytical model was developed using ANSYS and dynamic analysis was carried out using as input the wind induced pressure data acquired from the physical testing. At the first step, the analytical model was verified by comparing the analytical modal frequencies to the experimental natural frequencies obtained from the hammer test. It was shown that the analytical model can well represent the dynamic properties of the actual model. However, once the reaction output was compared to the loadcell data recorded during the wind tunnel test, there was a considerable discrepancy between the results. It was assumed that the deflection of the supporting structure caused this discrepancy. This assumption was verified and it was concluded that the supporting structure can significantly influence the dynamic response of the system.

Στη συγκεκριμένη διπλωματική εργασία μελετάται η δομή και η λειτουργία φωτοβολταϊκών πλαισίων πολυκρυσταλλικού πυριτίου. Για το σκοπό αυτό είναι απαραίτητη τόσο η θεωρητική μελέτη και περιγραφή της λειτουργίας τους, όσο και η πειραματική προσέγγιση του θέματος. Αρχικά, παρουσιάζεται η δομή των ηλιακών κυττάρων, βασικών δομικών μονάδων των φωτοβολταϊκών πλαισίων. Στην αρχή δίνεται μια περιεκτική περιγραφή της λειτουργίας της p-n επαφής ώστε στη συνέχεια να γίνει ευκολότερα κατανοητός ο τρόπος που επιδρά το φωτοβολταϊκό φαινόμενο στη δομή αυτή. Αναλύονται ορισμένα μεγέθη που χρησιμοποιούνται στην επιστήμη των φωτοβολταϊκών καθώς και οι συνθήκες στις οποίες μετρώνται παγκοσμίως τα ηλιακά κύτταρα/πλαίσια προκειμένου να υπάρχει ένα κοινό μέτρο σύγκρισης. Η μελέτη ολοκληρώνεται με την πειραματική διαδικασία. Σε αυτήν αναλύονται διεξοδικά οι παράγοντες που επηρεάζουν τη λειτουργία των φωτοβολταϊκών σε μια πραγματική εγκατάσταση. Οι παράγοντες αυτοί είναι κυρίως περιβαλλοντικοί (ηλιοφάνεια, θερμοκρασία). Υπάρχουν εξίσου σημαντικοί παράγοντες, όμως, που είναι δυνατό να μεταβληθούν από τον άνθρωπο με τρόπο ώστε να επιτευχθεί η βέλτιστη απόδοση. Πιο συγκεκριμένα, η γωνία κλίσης του πλαισίου και η περίπτωση της σκίασής του είναι απαραίτητο να ληφθούν σοβαρά υπόψη. Τα συμπεράσματα που προέκυψαν έχουν άμεση εφαρμογή στον υπολογισμό και τη μελέτη μιας πραγματικής εγκατάστασης μιας και δίνουν συγκεκριμένες αριθμητικές τιμές. Για παράδειγμα η συνολική αποδιδόμενη ετήσια ενέργεια από ένα πλαίσιο 80Wp τοποθετημένο με γωνία κλίσης ίση με τη βέλτιστη (380) στην περιοχή της Πάτρας είναι 172.038kWh. Αξιοσημείωτη είναι και η σύγκριση των πειραματικών τιμών ισχύος και συντελεστή απόδοσης με τις τιμές του κατασκευαστή και αυτές που προέκυψαν μέσω μοντελοποίησης (σε υπολογιστή με τα προγράμματα Matlab και Mathematica). Αυτές είναι: η μετρούμενη ισχύς του πλαισίου 73,15Watt και συντελεστής απόδοσης η=11,5%, ισχύς διδόμενη από τον κατασκευαστή 81,71Watt με συντελεστή απόδοσης η=12,6% και ισχύς η που προκύπτει από τη μοντελοποίηση 89,95Watt με συντελεστή απόδοσης η=14,2%. Η αιτιολόγηση αυτών των διαφορετικών τιμών ισχύος και των αντιστοίχων συντελεστών απόδοσης αποδίδεται στην αδυναμία να πετύχουμε ίδιες συνθήκες διεξαγωγής αυτών των μετρήσεων καθώς και στην σε σειρά και παράλληλη αντίσταση που δεν είναι δυνατόν να εκτιμηθούν ακριβώς για να εισαχθούν στο μοντέλο. / This thesis studies the structure and performance of polycrystalline silicon solar modules. To do this, not only a theoretical study of their operation is necessary, but also an experimental approach of the subject. In a first step, we can see the structure of polycrystalline silicon solar cells, which compose the solar panels. It was thought useful to give a compact description of the –p-n junction function. This way, the photovoltaic phenomenon’s impact on –p-n junction’s function can be easier understood. Along with the theoretical part, there is an analysis of some values that are used to the photovoltaic science along with the conditions that are used in order to have a common meter of comparison. A study, however, would not be completed if the experimental process did not exist. In this process the factors that influence the photovoltaic operation are analyzed at great length in a real installation. These factors are mainly environmental (sunlight, temperature). There are equally important factors, however, which are possible to be altered in such a way to achieve the most optimal performance. Specifically, the tilt angle and the shading case of the solar module are essential to be taken seriously into consideration. The results can be directly used for the calculation of a real installation and are very helpful as they are quite specific. For example, the total output power with a tilt angle of 380 at Patras-Greece is 172.038kWh. It is also remarkable to have a comparison between the experimental data, the data given by the constructor and the data gathered through simulation method. The values for the output power are 73,15Watt (η=11,5%), 81,71Watt (η=12,6%) and 89,95Watt (η=14,2%) respectively. The explanation of different power factor and output power comes from the inability to achieve exactly the same experimental conditions. Moreover, the shunt and series resistances cannot be calculated exactly due to lack of constructor’s data details.

Les concentrateurs photovoltaïques sont parmi les technologies d'énergies solaires les plus prometteuses. Ils ont une efficacité allant jusqu'à deux fois celle des panneaux photovoltaïques conventionnels. Malgré les avancements en recherche et développement, les concentrateurs photovoltaïques demeurent des systèmes relativement complexes. Cette même complexité laisse place à l'innovation et à la possibilité de réduire considérablement les coûts de fabrication. Dans le cadre de cette thèse, deux sites de tests sont développés et déployés pour faire l'analyse des performances des concentrateurs photovoltaïques plats. Quatre designs de cellules solaires sont caractérisés en laboratoire et incorporés dans les panneaux prototypes pour ensuite être individuellement étudiés. Les quatre designs sont ensuite comparés l'un à l'autre, et selon leurs emplacements, pour comprendre comment le design de la cellule affecte la performance des panneaux.

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This bachelor thesis investigates the implementation of a solar panel and battery storage system in a Swedish church that is intermittently heated focusing on its economic effect and its environmental impact in terms of CO2 emissions. The models are developed to evaluate the costs and CO2 emissions associated with power production, storage, usage and installation of the implemented system. The thesis examines two cases: Case 1, where all the energy is bought from the grid, representing the current energy usage in many churches, and Case 2 which assumes the integration of a solar panel and battery storage system. In terms of economic effects, the thesis reveals that the solar panel and battery storage system results in a negative impact on the church’s costs regarding energy usage. Over a period of 25 years, the church is projected to incur a loss of 956 400 SEK. However, it is worth noting that the direct energy costs when having an implemented solar panel and battery storage system are reduced by 33%, and the sale of surplus solar power generates an income of 1 816 100 SEK. Regarding the environmental impact, the implementation of the solar panel and battery storage system results in increased emissions compared to when only consuming the Swedish electricity mix. This is mainly due to the emissions regarding manufacturing of the solar panel and battery storage system. However, it is visible that the implementation of solely solar panels would lower the system’s total CO2 emissions. The sensitivity analysis demonstrates that replacing the Swedish electricity mix with the EU electricity mix for sold solar energy results in a positive environmental impact. This since the power generated from the solar panels replaces the European electricity mix which has a higher CO2- emission equivalent. This is important to consider since it is impossible to determine which electricity mix the sold PV energy will replace. In conclusion, while the implementation of a solar panel and battery storage system negatively affects the church’s energy costs and leads to increased CO2 emissions in the examined case, there are certain benefits to consider. The reduced energy bought from the grid and lowered direct energy costs, as well as the revenue from selling surplus solar power establishes the potential for the system to provide a positive impact. However, there is a need for advancements in battery technology for this to be a possibility.

Agrivoltaic (AV) systems are dual-use land systems that consist of elevated solar panels with crops grown underneath. They offer a solution to the increasing demand for food production and clean renewable energy. The main concern regarding AV systems is the reduced availability of light to crops below the panels. Research to date shows that AV systems are quite productive with total energy and crop production exceeding the outputs of either solar farms or crop production alone. Research also shows that solar panels affect the microenvironment below the panels. The research on AV systems so far considers altering panel density to increase radiation to the crops by varying the distance between rows of panels in an AV solar array. This study examines the crop outputs for Swiss chard, kale, pepper, and broccoli in an AV system with different gap spacings of 2, 3, 4, or 5 feet (AV plots) between panel clusters within rows to determine how much spacing between solar panels is optimal for crop production by comparing these system yields to full sun crop production. This study also examines the effect of the AV system on crop nutrient levels, on soil water content, and crop leaf temperature below the panels. Ultimately, the biomass crop yields of AV plots are restricted significantly for Swiss chard, kale, or pepper compared against the full sun control plot yields but not for broccoli stem + leaf yields. The 4-ft or 5-ft gap distances between panels yield the highest crop biomass of the AV shaded plots. Nutrient levels tend to increase with more shade but the trend is only significant for Swiss chard nitrogen and phosphorus concentrations, pepper potassium concentrations, and broccoli phosphorus concentrations. For soil water content it is found that panels have some effect on evapotranspiration and rainfall redistribution at the soil level. Leaf temperatures in the AV plots are lower than leaf temperatures in the control plots on sunny days but not on cloudy days.

Abstract Photovoltaic (PV) solar panels are solar energy collection systems with increasing terrestrial and roof applications reported worldwide. If the terrestrial mounting does not require specific wind resistance verifications, installing them on top of flat and gable roofs implies a drastic change of the roofing systems geometry, thus a re-evaluation of the wind-induced pressure is necessary. Among the roof top applications, provisions exist for the flat roofs mounted solar panels, however, design recommendations for wind-induced loadings on PV solar panels arrays flush-mounted on gable roofs are not fully developed in current wind loading standards (SEAOC PV2-2012) and building codes (ASCE 07, NBCC 2015), in spite of the numerous applications on residential and agricultural buildings, primarily due to the limited research investigating this topic. The current dissertation employs CFD k-ɛ and LE (Large Eddy) simulations for analyzing the effects of wind acting on solar panels flush-mounted on gable roofs, considering the influence of several parameters such as: the slope of the gable roof, the wind directions, the spaces between the adjacent solar panel arrays and the clearance between the roof surface and the solar panels. A comprehensive database of solar panels with different installation parameters subjected to wind speeds were developed under the current research project. The database includes detailed distribution of wind-induced pressure coefficients for the three parallel surfaces constituting the roof-solar panels systems: the top and bottom surfaces of the panels, and the roof surface under the panels, which represents a novel approach in investigating and clarifying the wind effects on solar panels. This approach also provides in detail the variation of the pressure coefficients on the three surfaces, due to the change of installation conditions (roof slope, arrays spacing, roof clearance) and wind parameters (wind speed and wind direction). As an original contribution to the existing knowledge, this thesis found that the installation of solar arrays on gable roofs, redistributes the wind-induced pressure on both sides of the roof windward and leeward, resulting in total horizontal wind-induced pressures on the entire roof lower than that registered on the corresponding roof without solar panels. In addition, dominant resultant pressure coefficients on solar panels concluded to be lower than for the roof without panels. When the roof clearance increases, total average pressure coefficients on the roof supporting the panels decreases on both, windward and leeward sides of the roof. Moreover, when the roof clearance increases, the pressures in the cavity decrease significantly on both windward and leeward sides of the roof, which could impact the requirements for installing and fixing such panels on gable roofs. For example, for 10” clearance the flush-mounted solar panels were subject to pressure instead of suction. Similarly, when panel array spacing increases, the magnitude of the net mean pressure coefficients on the roof surface under the solar panels further decreases for all wind directions investigated.