Advanced Materials Research Vols. 953-954

Abstract: Optical losses chiefly effect the power from a solar cell by lowering the short-circuit current. There are a number of ways to reduce the optical losses, which includes top contact coverage of the cell surface can be minimized, anti-reflection coatings can be used on the top surface of the cell, reflection can be reduced by surface texturing, and the optical path length in the solar cell may be increased by a combination of surface texturing and light trapping. This work discusses all of the methods to reduce optical losses of silicon solar cells. Surface texturing, either in combination with an anti-reflection coating or by itself, can be used to minimize reflection, but the large reflection loss can be reduced significantly via a suitable anti-reflecting coatings. Significant improvement of the short circuit current after light trapping design was observed. In addition to these methods, top contact design of silicon solar cells is important. The design of the top contact involves the minimization of the finger and busbar resistance, and the overall reduction of losses associated with the top contact.

Abstract: This paper presents a simulation and laboratory test of Photovoltaic (PV) module incorporated with Positive Output (PO) Buck-Boost Converter for harnessing maximum energy from the solar PV module. The main intention is to invent a system which can harvest maximum power point (MPP) energy of the PV system in string-connection. The model-based design of the controller and maximum power point tracking (MPPT) algorithm for the system were implemented using MATLAB SIMULINK software. For laboratory execution, the digital microcontroller of dsPIC30F digital signal controller (DSC) was used to control the prototype of PO buck-boost converter. The code generation via MPLAB Integrated Development Environment (IDE) from model-based design was embedded into the dsPIC30F using the SKds40A target board and PICkit 3 circuit debugger. The system was successfully simulated and verified by simulation and laboratory evaluations. A physical two PV module of PV-MF120EC3 Mitsubishi Electric is modeled in string connection to represent a mismatch module. While in laboratory process, a string-connection of 10W and 5W PV module is implemented for the mismatch module condition.

Abstract: With the increase of electrical equipment, people's lives become increasingly dependent on electricity. In case of power interruption, people need to use emergency power supply.A portable solar photovoltaic mobile emergency power supply is designed in this paper,which uses embedded solar panels to provide power energy, and fitted with other complementary power input.The designed portable solar photovoltaic mobile emergency power supply provides optional DC12V/5V and AC220V output to meet the application requirements on different occasions.Through experimental tests on designed power supply prototype, the results indicated the power supply has good performance in all aspects.The designed and developed portable solar photovoltaic mobile emergency power supply has characteristics of energy saving, full-featured, high practicability and wide application [1-5].

Abstract: Heating biogas digester is essential in northern China, especially during the winter. Solar energy-heated biogas digester is a facility that radiates heat by the solar thermal, which maintains the temperature of the biogas digester. The working principle behind this facility is the division of the traditional biogas digester into three parts, namely, raw material storage section, biogas slurry storage section, and anaerobic digestion section. We only heat the anaerobic digestion section to decrease the heating volume and reduce the heat dissipating surface, thereby saving energy. Solar energy is unstable, and the anaerobic digestion section needs to be maintained at its best temperature, thus, we control the raw material inlet at its optimum temperature. This biogas digester improves the anaerobic digestion condition and enhances gas production rate, which enables the efficient function of the digester during winter.

Abstract: Transient and daily thermal performances of the balcony-type solar water heater with a flat-plate collector were investigated under different weather conditions in Kunming. The results showed that the solar irradiance has a few influences on the thermal performance of the solar water heater. The system thermal efficiency is 50-57% when the daily total radiation varies from 5.3 to 22.2 MJ·m^-2. The initial temperature of the water in the water tank has great effects on the thermal efficiency. The daily thermal efficiency decreases by 9% when the initial temperature increases by 10°C. The percentage (Useful energy/Energy need) exceeds 60% when the daily total solar radiation is more than 11.6 MJ·m^-2. When the daily total solar radiation is larger than 21 MJ·m^-2, the useful energy output of the solar water heater can meet the user requirement for hot water.

Abstract: Based on the test methods for solar water heating systems, the unsteady thermal efficiency, the daily thermal efficiency and the daily water temperature rise of the balcony-type solar water heating system with a flat-plate solar collector fixed at a large tilt angle (≥60^o) have been discussed by the experimental test in Kunming. The results indicate that the average daily thermal efficiencies of the solar collector installed at 60^o, 70^o, 80^o and 90^o are around 0.35, 0.39, 0.34 and 0.40. The intercept and the slope of the unsteady thermal efficiency equations are about 0.36~0.44 and 1.62~4.01W·°C^-1·m^-2. The average daily water temperature rise is 25.2°C, 20.1°C, 18.2°C and 17.4°C for the solar collector fixed at 60^o, 70^o, 80^o and 90^o.

Abstract: Based on the test methods for solar water heating systems, the useful energy output, water temperature rise and thermal efficiency of the wall-type all-glass evacuated tube collectors fixed at a large tilt angle (≥60^o) have been conducted by the experimental test in Kunming. The results show that the average thermal efficiency varies from 35% to 50%, the useful energy output decreases from 13.1MJ to 8.8MJ and the water temperature rise decreases from 31.3 °Cto 20.9°C when the tilt angle increases from 60^o to 90^o. These results can provide some useful experimental data support for the application of the all-glass evacuated tube solar collector integrated into the wall of the high-rise buildings.

Abstract: s. In this paper, a new adsorption refrigeration system is designed and calculated. In this system, there are two beds, two condensers and two evaporators. The working principle is explained and specified in this paper. And mathematical models are also set up and through calculation, the system performance is analyzed and evaluated.Theory study results demonstrate that the new system nearly has the same cooling capacity as conventional system and this kind of system can be adopted in actual use.

Abstract: In this paper, the design is with the single chip microcomputer as the core of automatic tracking controller. The system is mainly composed of the signal acquisition part, the signal conditioning part, a control circuit and a drive circuit. The signal collection circuit composed of photosensitive resistance sensors to collect light signal, signal conversion circuit with voltage follower LM324 convert the change of light intensity to the change of the voltage, through the voltage comparator LM393 produce high and low level control stepping motor rotation; Control circuit use the AT89S52 as the main control device, output different control signals to the driving circuit; Driving circuit use the ULN2003 as driver stepper motor. Is obtained by simulation debugging, physical test, the error rate is less than 5%, in order to realize the efficient utilization of solar energy.

Abstract: Upconversion NaYF₄:Yb³⁺Er³⁺@TiO₂ are synthesized and used to compose the photoelectrode (PE) of dye-sensitized solar cells (DSSCs). The morphology, structure, photoluminescence characterization of the NaYF₄:Yb³⁺_, Er@TiO₂ and the photoelectric performance, alternating current impedance spectroscopy of DSSCs are characterized using transmission electron microscopy, CHI660C electrochemical analyzer, 720 nm long wave pass filter, the infrared laser light, upconversion spectra. Comparing the output power of the DSSC with upconversion performance at different annealing temperatures, the DSSCs under annealing temperature (330°C) show a better photovoltaic efficiency.