The Simulation And Optimization Of The Cascaded Luminescent Solar Concentrator

Due to the world wide energy shortage and serious environmental problems, searching for renewable energy to keep with the strategy of sustainable development is the common desire of people around the world. Among lots of renewable energy resources, solar energy has been the focus because of its unique advantages. It is also the most potential renewable energy in the 21st century. Among several effective utilization of solar energy, the development of the photovoltaic power generation is so fast and it is the most active research area in recent years. At present, the biggest challenge of the photovoltaic power generation system is the high cost and low efficiency. The electricity price is far more than the hydropower and thermal power, so the photovoltaic power generation did not show obvious advantages in economic aspect. Thus, the large-scale application of photovoltaic power generation is stunted. In recent years, governments are increasing subsidies for developing photovoltaic power generation. Governments have also promulgated a large number of preferential policies to encourage the development of photovoltaic power generation industry. To meet the large-scale application of photovoltaic power generation, the most fundamental solution is to reduce the cost of photovoltaic power generation and improve the photoelectric conversion efficiency of solar cells. After years of long-term exploration, one important approach of reduce the cost of solar power generation is to develop the concentration solar cells.In recent years, the development of conventional solar concentration photovoltaic technology has got good progress. However, the price of tracking system limits its development. By mixing luminescent material into the transparent medium, luminescent solar concentrator(LSC) is a new type of concentrator solar cells. LSC photovoltaic system can cut down the cost of photovoltaic electricity generation by reducing the consumption of solar cells. Single-layer LSC can be stacked from top to bottom to form cascaded luminescent solar concentrator photovoltaic system(C-LSC). In the cascaded LSC, the fluorescent material's absorption band of each layer LSC is different, with the absorption band / emission wavelength changes from short-wavelength to long-wavelength, and the bandgap of solar cells changes from wide to narrow. Comparing with the single layer LSC, the cascaded LSC can make use of solar spectrum effectively and obtain higher photoelectric conversion efficiency. In the practical application, the optical waveguide size, absorption band / emission wavelength of luminescent materials, solar cells band gap, and number of layers will all have impacts on the total photoelectric conversion efficiency. In this paper, the physical processes of the single layer LSC and cascaded LSC were analyzed. Based on the physical models, the simulation software was developed to calculate the photoelectric conversion efficiency of the single layer LSC and cascaded LSC. With the software photoelectric conversion efficiency and its dependency on side can be calculated, so that the spectral distribution can be optimized. This optimization results should can guide the fabrication of LSC, C-LSC. It has played a guiding role in experiment, avoiding a lot of detours.In this dissertation, we introduced the structure and described operating steps of the computer simulation software. As examples, we have chosen four different luminescent materials and two different solar cells to make two kinds of C-LSC. The calculation results indicate that the photoelectric conversion efficiency of the C-LSC made with Yellow083, Red305 materials is higher than that of the C-LSC made with NileRed, Phthalocyanine materials, indicating that the optimization of absorption band and emission wavelength of fluorescence materials is an effective approach to improve the photoelectric conversion efficiency. Then the waveguide transmission efficiency attenuates with size by exponential. Therefore, a reasonable choice of waveguide size can help to get the best cost effectiveness. Finally, we simulate the best band distribution of a semi-ideal three layers C-LSC and two layers C-LSC.