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In Korea, there is a rule for Renewable Energy Certification with weighting 5.0, to expand grid linkage capacity and to improve the stability of the grid to accommodate photovoltaic (PV) systems in a distributed power system. Due to this rule, many power companies and operators are trying to install electrical energy storage systems that are able to operate in conjunction with PV system power. These systems operate in parallel at the same grid connection point. This paper presents the results of case studies on the failure to detect islanding operation. Test evaluation devices that could be bi-directionally charged and discharged were implemented for an islanding detection test. Testing was conducted under a variety of operating conditions. When a single inverter was operated under the islanding condition, it was stably stopped within 0.5 s using the Korean grid-code standard. However, when two inverters were operated at the same time under the islanding condition, islanding detection failed and the two inverters continued to feed the connected RLC (resistor, inductor, capacitor) loads in the isolated section known as an island. Different algorithms used by PCS (power conversion system) manufacturers to detect islanding might cause this phenomenon. Therefore, it is necessary for a new PCS test standard to detect islanding. [ABSTRACT FROM AUTHOR]

In recent years, various types of installations such as floating photovoltaic (PV) and agri-voltaic systems, and BIPV (building integrated photovoltaic system) have been implemented in PV systems and, accordingly, there is a growing demand for new PV designs and materials. In particular, in order to install a PV module in a building, it is important to reduce the weight of the module. The PV module in which low-iron, tempered glass is applied to the front surface, which is generally used, has excellent electrical output and reliability characteristics; however, it is heavy. In order to reduce the weight of the PV module, it is necessary to use a film or plastic-based material, as opposed to low-iron, tempered glass, on the front surface. However, if a material other than glass is used on the front of the PV module, various problems such as reduced electrical output and reduced reliability may occur. Therefore, in this paper, a PV module using a film instead of glass as the front surface was fabricated, and a characteristic analysis and reliability test were conducted. First, the transmittance and UV characteristics of each material were tested, and one-cell and 24-cell PV modules were fabricated and tested for electrical output and reliability. From the results, it was found that the transmittance and UV characteristics of the front material were excellent. In addition, the electrical output and reliability test results confirmed that the front-surface film was appropriate for use in a PV module. [ABSTRACT FROM AUTHOR]

Cut solar cells have received considerable attention recently as they can reduce electrical output degradation when the c-Si solar cells (crystalline-silicon solar cells) are shaded. Cut c-Si solar cells have a lower short-circuit current than normal solar cells and the decrease in short-circuit currents is similar to the shading effect of c-Si solar cells. However, the results of this study's experiment show that the shadow effect of a c-Si solar cell reduces the V o c (open circuit voltage) in the c-Si solar cell but the V o c does not change when the c-Si solar cell is cut because the amount of incident light does not change. In this paper, the limitations of the electrical power analysis of the cut solar cells were identified when only photo current was considered and the analysis of the electric output of the cut c-Si solar cells was interpreted with a method different from that used in previous analyses. Electrical output was measured when the shaded and cut rates of c-Si solar cells were increased from 0% to 25, 50 and 75%, and a new theoretical model was compared with the experimental results using MATLAB. [ABSTRACT FROM AUTHOR]

Bypass diodes have been widely utilized in crystalline silicon (c-Si) photovoltaic (PV) modules to maximize the output of a PV module array under partially shaded conditions. A Schottky diode is used as the bypass diode in c-Si PV modules due to its low operating voltage. In this work, we systematically investigated the origin of bypass diode faults in c-Si PV modules operated outdoors. The temperature of the inner junction box where the bypass diode is installed increases as the ambient temperature increases. Its temperature rises to over 70 °C on sunny days in summer. As the temperature of the junction box increases from 25 to 70 °C, the leakage current increases up to 35 times under a reverse voltage of 15 V. As a result of the high leakage current of the bypass diode at high temperature, melt down of the junction barrier between the metal and semiconductor has been observed in damaged diodes collected from abnormally functioning PV modules. Thus, it is believed that the constant leakage current applied to the junction caused the melting of the junction, thereby resulting in a failure of both the bypass diode and the c-Si PV module. [ABSTRACT FROM AUTHOR]

H 2 plasma treatment was performed on carbon-based nonwoven fabrics (c-NFs) in a 900 W microwave plasma-enhanced chemical vapor deposition system at 750 °C and 40 Torr. Consequently, the electromagnetic wave shielding effectiveness (SE) of the c-NFs was significantly enhanced across the operating frequency range of 0.04 to 20.0 GHz. We compared the electromagnetic wave SE of the H 2 plasma-treated c-NFs samples with that of native c-NFs samples coated with nano-sized Ag particles. Despite having a lower surface electrical conductivity, H 2 plasma-treated c-NFs samples exhibited a considerably higher electromagnetic wave SE than the Ag-coated c-NFs samples, across the relatively high operating frequency range of 7.0 to 20.0 GHz. The carbon component of H 2 plasma-treated c-NFs samples increased significantly compared with the oxygen component. The H 2 plasma treatment transformed the alcohol-type (C-O-H) compounds formed by carbon-oxygen bonds on the surface of the native c-NFs samples into ether-type (C-O-C) compounds. On the basis of these results, we proposed a mechanism to explain the electromagnetic wave SE enhancement observed in H 2 plasma-treated c-NFs.