In the last few years, unglazed transpired solar collectors (UTCs) have proven to be an effective and viable method of reducing HVAC loads and building energy consumption. With the growing interest in PV/Thermal collectors, a study of a PV/Thermal UTC with PV cells mounted directly on the absorber was carried out. In the first part of this project, a TRNSYS model was developed to predict the performance of a PV/Thermal UTC. It was based on an actual UTC model, but modifications were made to account for the wind, the presence of PV cells and the corrugated shape of the plate. Simulations showed that mounting the cells only on the top surfaces of the corrugations prevented the cells from being shaded by the collector and consequently, presented the greatest potential. With this configuration, it was found that the addition of PV cells on the UTC decreased the thermal energy savings by 5.9 %, but that 13.6 % of the thermal energy savings could be recovered in the production of electricity. In the second part of the study, a prototype of a PV/Thermal UTC was constructed and tested outdoors. It was found that 10 % more electricity was obtained when the fan was turned on than for zero flow conditions. It was also observed that at greater air suction rates, more cooling of the panel was achieved and potentially higher electrical power could be produced. The effect of the PV cells on the collector thermal performance could not be quantified, however, due to the small portion of PV cells on the whole collector area. TRNSYS simulations were performed using the prototype parameters and the weather data of some experimental days. The results predicted by the component developed showed similar trends as the experimental results. The predictions were, however, not within the experimental uncertainties. The deviation in the results was attributed to the fact that the wind heat losses were not estimated accurately by the model and the non-uniform suction at the panel surface that prevented the prototype tested to work at its optimal performance.

In the last few years, unglazed transpired solar collectors (UTCs) have proven to be an effective and viable method of reducing HVAC loads and building energy consumption. With the growing interest in PV/Thermal collectors, a study of a PV/Thermal UTC with PV cells mounted directly on the absorber was carried out. In the first part of this project, a TRNSYS model was developed to predict the performance of a PV/Thermal UTC. It was based on an actual UTC model, but modifications were made to account for the wind, the presence of PV cells and the corrugated shape of the plate. Simulations showed that mounting the cells only on the top surfaces of the corrugations prevented the cells from being shaded by the collector and consequently, presented the greatest potential. With this configuration, it was found that the addition of PV cells on the UTC decreased the thermal energy savings by 5.9 %, but that 13.6 % of the thermal energy savings could be recovered in the production of electricity. In the second part of the study, a prototype of a PV/Thermal UTC was constructed and tested outdoors. It was found that 10 % more electricity was obtained when the fan was turned on than for zero flow conditions. It was also observed that at greater air suction rates, more cooling of the panel was achieved and potentially higher electrical power could be produced. The effect of the PV cells on the collector thermal performance could not be quantified, however, due to the small portion of PV cells on the whole collector area. TRNSYS simulations were performed using the prototype parameters and the weather data of some experimental days. The results predicted by the component developed showed similar trends as the experimental results. The predictions were, however, not within the experimental uncertainties. The deviation in the results was attributed to the fact that the wind heat losses were not estimated accurately by the model and the non-uniform suction at the panel surface that prevented the prototype tested to work at its optimal performance.

This thesis discusses aspects of a novel solar concentrating photovoltaic / thermal (PV/T) collector that has been designed to produce both electricity and hot water. The motivation for the development of the Combined Heat and Power Solar (CHAPS) collector is twofold: in the short term, to produce photovoltaic power and solar hot water at a cost which is competitive with other renewable energy technologies, and in the longer term, at a cost which is lower than possible with current technologies. To the author’s knowledge, the CHAPS collector is the first PV/T system using a reflective linear concentrator with a concentration ratio in the range 20-40x. The work contained in this thesis is a thorough study of all facets of the CHAPS collector, through a combination of theoretical and experimental investigation. A theoretical discussion of the concept of ‘energy value’ is presented, with the aim of developing methodologies that could be used in optimisation studies to compare the value of electrical and thermal energy. Three approaches are discussed; thermodynamic methods, using second law concepts of energy usefulness; economic valuation of the hot water and electricity through levelised energy costs; and environmental valuation, based on the greenhouse gas emissions associated with the generation of hot water and electricity. It is proposed that the value of electrical energy and thermal energy is best compared using a simple ratio. Experimental measurement of the thermal and electrical efficiency of a CHAPS receiver was carried out for a range of operating temperatures and fluid flow rates. The effectiveness of internal fins incorporated to augment heat transfer was examined. The glass surface temperature was measured using an infrared camera, to assist in the calculation of thermal losses, and to help determine the extent of radiation absorbed in the cover materials. FEA analysis, using the software package Strand7, examines the conductive heat transfer within the receiver body to obtain a temperature profile under operating conditions. Electrical efficiency is not only affected by temperature, but by non-uniformities in the radiation flux profile. Highly non-uniform illumination across the cells was found to reduce the efficiency by about 10% relative. The radiation flux profile longitudinal to the receivers was measured by a custom-built flux scanning device. The results show significant fluctuations in the flux profile and, at worst, the minimum flux intensity is as much as 27% lower than the median. A single cell with low flux intensity limits the current and performance of all cells in series, causing a significant drop in overall output. Therefore, a detailed understanding of the causes of flux non-uniformities is essential for the design of a single-axis tracking PV trough concentrator. Simulation of the flux profile was carried out using the ray tracing software Opticad, and good agreement was achieved between the simulated and measured results. The ray tracing allows the effect of the receiver supports, the gap between mirrors and the mirror shape imperfections to be examined individually. A detailed analytical model simulating the CHAPS collector was developed in the TRNSYS simulation environment. The accuracy of the new component was tested against measured data, with acceptable results. A system model was created to demonstrate how sub components of the collector, such as the insulation thickness and the conductivity of the tape bonding the cells to the receiver, can be examined as part of a long term simulation.

Solar photovoltaic-thermal (PVT) modules produce heat and power via a heat exchanger attached to the rear of the PV cells. The novel PVT collector in this study is previously untested and therefore its behaviour and thermo-electric performance due to fluid channel configuration and in various climate and operating conditions are unknown. Moreover, the working fluid flowing through the heat exchanger cause a temperature gradient across the module such that a cell near the inlet and a cell near the outlet may have significant temperature differences. PV cells are sensitive to temperature; however the most common way to simulate power output from a PVT is to use the average temperature and ignore the gradient. In this study, a single diode PV model is incorporated into a commercial thermal solver to co-simulate the thermal and electrical output of a novel PVT module design with cell level resolution. The PVT system is modelled in steady state under various wind speeds, inlet temperatures, ambient temperatures, flow rates, irradiation, convection coefficients from coolant and back of the module and two different fluid channel configurations. The results show that of the controllable variables, the inlet temperature has the highest influence of the total power output and that a parallel flow of the fluid channel configuration is preferable. The difference between the cell resolution and the module resolution simulations do not motivate the use of a higher resolution numerical simulation. / En kombinerad solcellspanel och solvärmefångare (PVT) producerar värme och elenergi på samma yta genom att en värmeväxlare upptar värmen från baksidan av solcellspanelen. Den PVT som berörs i denna studien är nyutvecklad och har aldrig tidigare testats, vilket medför att data för hur den beter sig samt dess termo-elektiska prestanda saknas för olika driftförhållanden samt flödeskonfigurationer. Vidare ger mediet som flödar genom värmeväxlaren upphov till en temperaturgradient, vilken kan innebära en påtaglig skillnad i temperatur mellan solcellerna i solcellspanelen vid mediets in- respektive utlopp. Trots solcellers temperaturkänslighet, så sker simulering i allmänhet med avseende på panelens medeltemperatur istället för att hänsyn tas till denna temperaturgradient. I den här studien implementeras en så kallad  ”single diode”-modell i en kommersiell numerisk mjukvara termiska beräkningar för att samsimulera termiskt och elektriskt effektuttag ur den nyutvecklade PVT-designen. Designen modelleras statiskt under givna variationer av vindhastighet, inloppstemperatur, omgivande temperatur, flödeshastighet, solinstrålning och konvektionskoefficienter för mediet samt baksidan av modulen. Resultaten visar att kontrollerbara variabler som inloppstemperatur har högst inverkan på den totala effekten samt att en parallell flödeskonfiguration lämpar sig bäst. Studien visar också att skillnaden mellan simulering på cellnivå och modulnivå inte motiverar en numerisk beräkningsmetod med upplösning satt till solcellsnivå.

The global need to eliminate CO2 emissions and its consequent reduction in the use of fossil fuels drives the ongoing energy transition that highly involves the research achievements of the scientific community to reach the goals of this purpose. Renewable sources like photovoltaic and wind energy, are central to this endeavor, however, the intermittency of natural resources makes it non-dispatchable and energy storage is fundamental. According to the European Roadmap [1] just a 60% of the CO2 emissions reduction goal can be achieved with available technologies and existing energy. However, the production, use and specially storage opportunities that hydrogen offers can drive non-dispatchable renewable sources to achieve its full potential by clearing up the intermittency problem as well as covering the remained 40% gap. This master's thesis aims to investigate the techno-economic feasibility of integrating a Solid Oxide Electrolyzer Cell (SOEC) into a hybrid PV-CSP(sCO2) plant. The study focuses on assessing various indicators related to electricity, energy, and hydrogen production prices. To achieve this, three different integration strategies within the hybrid PV-CSP(sCO2) plant were selected for analysis: Soec using heat from the particles coming from the receiver, soec using heat coming from the particles available in the thermal energy storage (TES) and soec recovering heat from the sCO2 power block. A sensitivity analysis was conducted on different PV sizes (MWp), battery capacities (MWh), and SOEC installed capacities (MWh) to investigate the technology's potential in the plant and determine optimal sizing of subsystems. However, the individual optimization of economic indicators presented technical and economic challenges. Scenarios allowing individual optimization of hydrogen production prices (€/kg H2) resulted in 10.9, 11.7, and 14.6 €/kg h2 for receiver, TES, and sCO2 integration strategy, respectively. These scenarios, however, require high SOEC installed capacities, leading to elevated electricity and energy production prices. On the other hand, the individual optimization of electricity and energy production prices led to better and lower results when no hydrogen production presence within the plant. However, this analysis also showed that soec capacities below 5MWh together with no installation of batteries and a new definition for calculating hydrogen production prices (LCOH) allows feasible integration of hydrogen production within the plant. LCOH(€/kg h2) results were 10.2€/kg h2, 7.6€/kg h2, and 9.4€/kg h2 for receiver, TES, and sCO2, respectively, for a soec installed capacity of 0.5MWh (119m2 size) along with energy production values not exceeding 101€/MWh. While the results present a favorable outlook for SOEC installations based on literature review data [2] [3] [4] they still face challenges when competing with the cost-efficient PEM technology, which offers 4.5-5.5€/kg H2 [5] without storage. Nonetheless, this research contributes valuable insights into the integration of SOEC technology within hybrid renewable energy systems and provides a comprehensive analysis of the techno-economic aspects related to hydrogen production following different integration strategies. The findings may inform decision-making processes and promote further advancements in sustainable energy solutions. / Det globala behovet av att eliminera CO2utsläpp och därmed minska användningen av fossila bränslen driver pågående energiomställning, som starkt involverar forskningsresultaten från vetenskapssamhället för att nå syftet med detta mål. Förnybara källor som solceller och vindkraft är centrala i detta arbete, men intermittensen hos naturliga resurser gör dem icke disponibla och energilagring är grundläggande. Enligt den europeiska vägkartan [1] kan endast 60% av målet att minska CO2-utsläppen uppnås med tillgängliga teknologier och befintlig energi. Produktionen, användningen och särskilt lagringsmöjligheterna som väte erbjuder kan emellertid driva icke-disponibla förnybara källor att nå sin fulla potential genom att lösa intermitt ensproblemet och täcka den återstående 40% klyftan. Detta examensarbete syftar till att undersöka den tekniskekonomiska genomförbarheten av att integrera en fastoxid elektrolysör (SOEC) i en hybrid PV CSP(sCO2)-anläggning. Studien fokuserar på att utvärde ra olika indikatorer relaterade till el-, energi- och vätgasproduktionspriser. För att uppnå detta har tre olika integrationsstrategier inom hybrid PV CSP(sCO2) anläggningen valts för analys: SOEC med hjälp av värme från partiklar som kommer från mottagaren, SOEC med hjälp av värme från partiklar som finns i termisk energilagring (TES) och SOEC som återvinner värme från sCO2-kraftblocket. En känslighetsanalys har genomförts för olika PVstorlekar (MWp), batterikapaciteter (MWh) och SOEC installerade kapacit eter (MWh) för att undersöka teknologins potential i anläggningen och bestämma optimal dimensionering av delsystem. Resultaten från individuell optimering av ekonomiska indikatorer ledde dock till flera tekniska och ekonomiska utmaningar. Scenarier som tillåter individuell optimering av vätgasproduktionspriser (€/kg H2) resulterade i 10, 9, 11, 7 respektive 14,6 €/kg H2 för mottagare, TES och sCO2 integrationsstrategi. Dessa scenarier kräver dock höga SOEC installerade kapaciteter, vilket leder till höga el och energipriser. Å andra sidan ledde individuell optimering av el och energiproduktionspriser till bättre och lägre resultat när ingen vätgasproduktion fanns i anläggningen. Denna analys visade också att SOEC kapaciteter under 5MWh tillsammans med ingen installation av batterier och en ny definition för beräkning av vätgasproduktionspriser (LCOH) möjliggör genomförbar integration av vätgasproduktion i anläggningen. LCOH (€/kg H2) resultaten var 10,2 €/kg h2 , 7 ,6 €/kg h2 respektive 9,4 €/kg h2 för mottagare, TES och sCO2, för en SOEC installerad kapacitet på 0,5 MWh (storlek 119m2) tillsammans med energiproduktionsvärden som inte överstiger 101 €/MWh. Medan resultaten visar en gynnsam utsikt för SOECinstallationer baserat på data från litteraturöversikter [2] [3] [4], står de ändå inför utmaningar när de konkurrerar med den kostnadseffektiva PEM teknologin, som erbjuder 4,5-5,5 €/kg H2 [5] utan lagring. Trots detta bidrar forskningen med värdefulla insikter i integrationen av SOEC teknologi i hybrid förnybara energisystem och ger en omfattande an alys av de teknisk-ekonomiska aspekterna relaterade till vätgasproduktion enligt olika integrationsstrategier. Resultaten kan informera beslutsprocesser och främja ytterligare framsteg inom hållbara energilösningar.

In Photovoltaic/Thermal (PVT) technology, both PV and solar thermal technology are integrated in the same module for simultaneous electricity and heat production. Research has shown that there are multiple benefits from integrating PVT collectors with a ground source heat pump (GSHP) system, since it allows for seasonal storage of thermal energy over the year. Furthermore, it leads to reduced operating temperatures for the PVT collectors which can increase efficiency and lifetime. The aim of this study is to present the electric and thermal performance of a PVT collector developed by Solhybrid i Småland AB, for different environmental and fluid inlet conditions that can occur when PVT collectors are connected to a GSHP system. Furthermore, the performance of this PVT design is evaluated with ASHRAE (Standard 93-2003), to allow for comparison with other PVT collector designs, with values on the overall heat loss coefficient (UL) and heat removal factor (FR). The modelling tool used for the study is the software COMSOL Multiphysics, which uses the finite element method to solve the partial differential equations in heat transfer and fluid flow problems. Based on the performance curves, the thermal and electrical efficiency of the collector is approximately 48.0-53.4% and 19.0-19.2% respectively at a reduced temperature of zero and irradiance levels of 800-1000 W/m2 for the mass flow rate of 0.026 kg/sm2 which was determined as most suitable to increase thermal performance. Furthermore, these results resulted in a heat removal factor (FR) and overall heat loss coefficient (UL) of 0.56-0.62 and 53.4-53.5 W/m2 K respectively. The results on the performance of the PVT collector in different weather conditions shows that the inlet water temperature can significantly affect operating time and the amount of thermal energy that can be extracted during the year, especially if the collector operates in a colder climate like Sweden. To assess the accuracy of the created model, future work includes experimental testing of the studied PVT collector. / En panel med kombinerad teknik av både solceller och termisk solfångare (PVT) kan producera både elektricitet och värme samtidigt. Forskning har visat att det kan finnas flera fördelar med att integrera PVT-paneler med ett bergvärmesystem, eftersom det mjliggör lagring av termisk energi över året. Dessutom leder ett sådant system till lägre drifttemperaturer som kan öka PVT-panelens effektivitet och livslängd. Syftet med studien är att presentera den elektriska och termiska prestandan av en PVT-panel utvecklat av Solhybrid i Småland AB för olika driftförhållanden som kan uppstå på grund av olika väderförhållanden och inlopps-temperaturer när panelerna är kopplade till ett bergvärmesystem. Vidare utvärderas prestandan för denna panel med ASHRAEmetoden (standard 93-2003), för att möjliggöra jämförelse med andra PVT-paneler. Modelleringsverktyget som använts i studien är mjukvaran COMSOL Multiphysics, som använder finita elementmetoden för att lösa partiella differentialekvationer i värmeöverförings-och flödesproblem. Baserat på prestandakurvorna som presenteras i resultatet, är den termiska och elektriska verkningsgraden approximativt 48.0-53.4% respektive 19.0-19.2% för en reducerad temperatur med värdet noll, en solstrålning mellan 800-1000 W/m2, för en massflödeshastighet på 0.026 kg/sm2 som beslutades som den mest lämpliga för att öka den termiska prestandan. Resultaten resulterade i en värmeavledningsfaktor (FR) och total värmeförlustkoefficient (UL) på 0.56-0.62 respektive 53.4-53.5 W/m2 K. Resultaten på PVT-panelens prestanda under olika väderförhållanden visar att vattnets inloppstemperatur kan påverka drifttiden och mängden termisk energi som kan extraheras under året avsevärt, speciellt i nordiskt klimat. För att bedöma korrektheten i resultaten och den skapade modellen rekommenderas experimentell testning av den studerade PVT-panelen.