Optimization And Novel Luminescent Solar Concentrators

This dissertation, titled "Optimization and novel luminescent solar concentrators", consists of three chapters. The first chapter gives a literature review. Chapter two describes the aqueous layer LSC (luminescent solar concentrator) and PMMA-based LSCs fabricated by in-situ polymerization method. The last chapter is the study of the bottom-mounted PV cell LSC (BMP-LSC).Chapter one reviews the related LSC backgrounds knowledge and research progresses. At first, a brief introduction to the principle of solar cells is given. The background, current state and perspective of solar cells, especially the building-integrated photovoltaics (BIPV), are also summarized. Secondly, the research progresses of LSCs are introduced from the loss mechanisms of LSCs. The influencing factors of LSC efficiencies and existing problems are also discussed. Finally, the research proposal of this dissertation is presented.In chapter two, the optimization of LSC fabrication technique is studied. Firstly, an aqueous layer LSC with size of78mm×78mm×7mm is fabricated by injecting fluorescent solution into the layer between two pieces of flat glass. After coupled with silicon solar cell, the concentrator shows a power conversion efficiency of3.9%, about30%higher than that of the same sized laminated glass LSC employing the same dyes. Furthermore, the measured efficiency almost reaches the calculation limit of the aqueous layer LSC. The reason is attributed to the very low optical transmission loss of the fabricated aqueous layer LSC. This kind of aqueous layer LSC offers a potential application in BIPV. Secondly, PMMA-based LSCs are fabricated using in-situ polymerization method. It is found that the transmission loss can be reduced as compared with the laminated glass waveguide due to the dusts and bubbles in the waveguide medium can be easily avoided, and LSC efficiency can achieve4.10%which is close to the highest experimental LSC efficiency for crystalline silicon PVs. After attaching three edges with reflecting mirrors and one edge with silicon solar cell, the concentrator shows an output power of109.5mW, exhibiting an effective concentrating effect. The contribution of different parts of PMMA waveguide to the output power of coupled cell is studied to reveal the influence of reflecting mirror and white bottom reflector on the transport process of the waveguided light. It shows that reflecting mirror and white bottom reflector can increase the contribution of different parts of PMMA waveguide to the output power of coupled cell. Furthermore, the increase effect is more obvious in the short distance for white bottom reflector, while more obvious in the long distance for reflecting mirrors.In chapter three, novel LSC layouts are proposed to solve the transmission loss and narrow-absorption problem in LSC. BMP-LSCs with size of78mm×78mm×7mm based dye-doped PMMA plates are fabricated and their gain and power conversion efficiency are investigated. This LSC layout absorbs not only the waveguided light but also the transmitted sunlight and partial fluorescent light in the escape cone. The transport process of the waveguided light and the relationship between the bottom-mounted cells is studied for the optimization of the BMP-LSC performance. The BMP-LSC coupled with one cell displays a power gain of1.38, to our best knowledge, which is the highest value for dye-doped PMMA plate LSCs. Power conversion efficiency as high as5.03%is obtained with three cells coupled. Furthermore, the BMP-LSC is found to have a lowest cost per watt of$1.89with two cells coupled. The influence of distance of two cells on LSC efficiency is studied and LSC with two cells coupled with distance of29mm shows the highest cell gain, which is attributed to the competitive absorption of the waveguided light among two coupled cells and the transport length of waveguided light. Finally, the application of BMP-LSC in BIPV is envisaged.