COMPUTATIONAL SIMULATION AND ANALYSIS OF MAJOR CONTROL PARAMETERS OF TIME-DEPENDENT PV/T COLLECTORS

In order to improve the transient performance of photovoltaic/thermal (or PV/T for simplicity) collectors, this paper firstly developed and validated a computational thermal model to investigate the effects of the major control parameters on the thermal performance of PV/T collectors, including inlet water temperature and inlet water flow rate. Secondly, a computational electrical model of PV/T system, coupled with the thermal model, was also introduced to elaborate the relationship of voltage, current and power of a PV module (MSX60 poly-crystalline solar cell) used in an experiment in the literature. The thermal and electrical models were solved simultaneously to predict the transient energy conversion efficiencies of the PV/T system. Simulation results were found to agree with the experimental data very well. The effects of the time-steps from 1 hour to 1 minute, which is closed to the real time, were also reported at various conditions. It was found that both thermal and electrical efficiencies are fluctuating with time. There is an optimal water flow rate at which the efficiencies are at the maximum. At last, several suggestions to improve the efficiency of PV/T system were discussed.

Atomic-scale microstructure of metal halide perovskite

Hybrid organic-inorganic perovskites have high potential as materials for solar energy applications, but their microscopic properties are still not well understood. Atomic-resolution scanning transmission electron microscopy has provided invaluable insights for many crystalline solar cell materials, and we used this method to successfully image formamidinium lead triiodide [CH(NH2)2PbI3] thin films with a low dose of electron irradiation. Such images reveal a highly ordered atomic arrangement of sharp grain boundaries and coherent perovskite/PbI2 interfaces, with a striking absence of long-range disorder in the crystal. We found that beam-induced degradation of the perovskite leads to an initial loss of formamidinium [CH(NH2)2+] ions, leaving behind a partially unoccupied perovskite lattice, which explains the unusual regenerative properties of these materials. We further observed aligned point defects and climb-dissociated dislocations. Our findings thus provide an atomic-level understanding of technologically important lead halide perovskites.

A Conversion Efficiency Determination of High Efficiency Solar Cells with Parabolic Dish Concentrating System

Aims: Field test for the conversion efficiency determination of high concentrating solar cells with parabolic dish concentrating system in a tropical location. Background: Typical solar cell system using in a tropical location is a fixed panel via commercial grade mono crystalline, poly crystalline or amorphous solar panels. They have low conversion efficiency so they need wide area to enhance the electrical energy. The consequence is low yielding in terms of economics and unpopular used in urban zone. Objective: To test for the conversion efficiency determination of high concentrating solar cells with parabolic dish concentrating system in a tropical location. Method: The research was conducted at the top of Nakhon Ratchasima Rajabhat University(NRRU) Science Center Building, Nakhon Ratchasima, Thailand. The four multi junction solar cells were connected together to receive the reflecting concentrated sunlight from the parabolic dish. I also determined the conversion efficiency of the 160 watts peak mono crystalline solar cell panel for a comparing purpose. Multi junction solar cells with parabolic dish concentrating and cooling systems, solar cell panel, pyrheliometer, pyranometer and light sensor were set up on the dual axes sun tracker. Data were gathered every 5 minutes all day from January 2018 to February 2019 for all 3 seasons via the automatic data logging system. Result: The results had presented that the average conversion efficiency of high concentrating solar cell module with parabolic dish concentrating system for 100x and of the 160 watts peak mono crystalline solar cell panel were 15.18% and 9.46% respectively, with the percentage difference of 56.45%. While, the average output powers per unit area per year of multi junction solar cells with concentrating system and mono crystalline solar cell panel were 98,544.92watt/m2 and 664.37watt/m2 respectively, with the ratio of 148.33. Conclusion: It is clearly seen that, in terms of conversion efficiency and output power per unit area per year, the multi junction solar cells with parabolic dish concentrating system has more advantage than the typical mono crystalline solar cell panel. Other: Especially for economical aspect, the utilization of parabolic dish concentrating system with MJ solar cells can reduce the land investment cost and also encourage of solar cell utilization not only in rural but also in urban for the tropical climate countries.

Computational Simulation and Analysis of Major Control Parameters of Time-Dependent PV/T Collectors

In order to improve performance of photovoltaic/thermal (or PV/T for simplicity) collectors, this paper firstly validated a previous computational thermal model and then introduced an improved computational thermal model to investigate the effects of the major control parameters on the thermal performance of PV/T collectors, including solar cell temperature, back surface temperature, and outlet water temperature. Besides, a computational electrical model of PV/T system was also introduced to elaborate the relationship of voltage, current and power of a PV module (MSX60 poly-crystalline solar cell) used in an experiment in the literature. Simulation results agree with the experimental data very well. The effects of the time-steps from 1 hour to minute, which is closed to the real time, were also reported. At last, several suggestions to improve the efficiency of PV/T system were illustrated.

An Efficient and Simple Method for Modelling Solar Cells

Accurate and reliable PV device modelling is a fundamental tool to optimize system performance. The regular operation of the PV system in an outdoor condition implies the need for a model that relate the environmental effects. This paper presents a new, simple, and efficient method for constructing the I-V characteristics for a PV cell incorporating the environmental conditions. The proposed model is based on the idea of dividing the voltage axis of the solar cell I-V characteristics using a fixed time interval. For each voltage interval point, a two-dimensional current matrix is calculated, corresponding different irradiance conditions and temperatures. Polynomial surface fitting is used to build sub-models for each voltage interval. The current two-dimensional matrix, for each point, is calculated by two different methods. The first method is based on linear interpolation of the measured I-V curves. The second method uses pre-extracted five parameters for the well known single diode model at a wide range of environmental conditions. The developed modelling technique provides accurate results compared with the measured data for a mono-crystalline solar cell.