Design of Spectral Beamsplitter for Hybrid Thermoelectic / Photovoltaic Concentrated Solar Energy Devices
Author
Skjølstrup, Enok Johannes Haahr
Term
4. term (FYS10)
Education
Publication year
2016
Submitted on
2016-06-08
Pages
109
Abstract
Specialet har til formål at optimere en stråledeler til et hybridsystem, der kombinerer en solcelle med et termoelektrisk element. Stråledeleren er en stak af mere end 100 skiftevis lag af silicium-nitrid (Si3N4) og silicium-dioxid (SiO2) på glas, afsluttet med magnesiumfluorid (MgF2). Ved at justere tykkelsen af hvert lag er målet at sende de mest nyttige dele af sollyset til solcellen og resten til det termoelektriske element for at maksimere den samlede virkningsgrad. To ækvivalente transfer-matrix-metoder bruges til at beregne, hvordan multilagsstrukturen transmitterer, reflekterer og absorberer lys. Undersøgelsen evaluerer mikrokrystallinske og amorfe solceller og finder de lagtykkelser, der giver den bedste samlede ydeevne. Resultaterne viser, at det på grund af højereordens båndgab i strukturen ikke er muligt at lave en lav-bølgelængde-pass stråledeler (som primært lader korte bølgelængder passere), mens en høj-bølgelængde-pass løsning fungerer godt. Den mikrokrystallinske solcelle har højere absolut virkningsgrad end den amorfe, men den relative forbedring ved at bruge hybridsystemet med en høj-bølgelængde-pass stråledeler er næsten dobbelt så stor for den amorfe solcelle.
This thesis aims to optimize a beamsplitter for a hybrid system that combines a solar cell with a thermoelectric element. The beamsplitter is a stack of more than 100 alternating layers of silicon nitride (Si3N4) and silicon dioxide (SiO2) on glass, finished with magnesium fluoride (MgF2). By tuning the thickness of each layer, the goal is to direct the most useful parts of sunlight to the solar cell and the rest to the thermoelectric element, maximizing overall efficiency. Two equivalent transfer-matrix methods are used to compute how the multilayer stack transmits, reflects, and absorbs light. The study evaluates microcrystalline and amorphous solar cells and identifies the layer thicknesses that yield the best combined performance. The results show that, because of higher-order band gaps in the structure, a low-wavelength-pass beamsplitter (one that mainly lets short wavelengths through) cannot be achieved, whereas a high-wavelength-pass design works well. The microcrystalline solar cell has higher absolute efficiency than the amorphous one, but the relative efficiency gain from using the hybrid system with a high-wavelength-pass beamsplitter is nearly twice as large for the amorphous cell.
[This abstract was generated with the help of AI]
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