Current Issue : July - September Volume : 2018 Issue Number : 3 Articles : 5 Articles
This work presents the development of a solar regulator which manages the\ncharge and discharge of a (lead) battery installed in a photovoltaic system in\norder to extend its lifetime. The regulator is controlled by a microcontroller\n(PIC16F877A) and protects the battery against overcharging, deep discharge,\nbut also against temperature drifts. The operating principle is based on the\ncontrol of a DC-DC converter by a rectangular signal MLI generated by the\nmicrocontroller. In addition to the protection function of the regulator, there\nis included a control and monitoring panel consisting of a visualization interface\non which the system quantities can be observed. Thus, it will be given to\nthe user to be able to act on the system. This display interface uses as a display\nan LCD screen and LEDs. Simulation results are presented to illustrate the\noperation of the proposed solar controller....
Previous works revealed that cross-corrugated absorber plate design and jet impingement on a flat absorber plate resulted\nin a significant increase in the performance of a solar air heater (SAH). Involving these two designs into one continuous\ndesign to improve the SAH performance remains absent in the literature. This study aimed to evaluate the achieved\nenhancement on performance parameters of a SAH with jet impingement on a corrugated absorber plate. An energy\nbalance model was developed to compare the performance parameters of the proposed SAH with the other two SAHs.\nAt a clear sky day and a mass flow rate of 0.04 kg/s, the hourly results revealed that the max fluid outlet temperatures for the\nproposed SAH, jet-to-flat plate SAH, and cross-corrugated plate SAH are 321, 317, and 313 K, respectively; the max\nabsorber plate temperatures are 323.5, 326.5, and 328 K, respectively; the maximum temperature differences between the\nabsorber plate and fluid outlet are ~3, 9, and 15 K, respectively; the max efficiencies are 65.7, 64.8, and 60%, respectively.\nStatistical t-test results confirmed significant differences between the mean efficiency of the proposed SAH and SAH with\njet-to-flat plate. Hence, the proposed design is considered superior in improving the performance parameters of SAH\ncompared to other designs....
This paper presents an experimental and theoretical study on the impact of doping and recombination mechanisms on quantum dot\nsolar cells based on the InAs/GaAs system. Numerical simulations are built on a hybrid approach that includes the quantum features\nof the charge transfer processes between the nanostructured material and the bulk host material in a classical transport model of the\nmacroscopic continuum. This allows gaining a detailed understanding of the several physical mechanisms affecting the photovoltaic\nconversion efficiency and provides a quantitatively accurate picture of real devices at a reasonable computational cost.\nExperimental results demonstrate that QD doping provides a remarkable increase of the solar cell open-circuit voltage, which is\nexplained by the numerical simulations as the result of reduced recombination loss through quantum dots and defects....
The current study presents a numerical and real-time performance analysis of a parabolic trough collector (PTC) system designed\nfor solar air-conditioning applications. Initially, a thermodynamic model of PTC is developed using engineering equation solver\n(EES) having a capacity of around 3 kW. Then, an experimental PTC system setup is established with a concentration ratio of\n9.93 using evacuated tube receivers. The experimental study is conducted under the climate of Taxila, Pakistan in accordance\nwith ASHRAE 93-1986 standard. Furthermore, PTC system is integrated with a solid desiccant dehumidifier (SDD) to study the\neffect of various operating parameters such as direct solar radiation and inlet fluid temperature and its impact on\ndehumidification share. The experimental maximum temperature gain is around 5.2�°C, with the peak efficiency of 62% on a\nsunny day. Similarly, maximum thermal energy gain on sunny and cloudy days is 3.07kW and 2.33 kW, respectively.\nAfterwards, same comprehensive EES model of PTC with some modifications is used for annual transient analysis in TRNSYS\nfor five different climates of Pakistan. Quetta revealed peak solar insolation of 656W/m2 and peak thermal energy 1139 MJ with\n46% efficiency. The comparison shows good agreement between simulated and experimental results with root mean square error\nof around 9%....
The presence of microcracks may lead to loss in the module output power and safety hazard of the module. This paper investigated\nwhether the existed microscopic microcracks in cells will facilitate the PID behavior. Cells with different degrees of microcracks\nwere fabricated into small modules to undergo the simulated PID test. The I-V performance and EL images of the modules were\ncharacterized before and after the PID test. The obtained results demonstrate that with the increase in the microcracked area or\nlength, the modules would show a more serious PID behavior. The mechanism of this microcrack length-related degradation\nunder high negative bias was proposed....
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