• Research Article

    Study of Light-induced Degradation in Thin Film Silicon Solar Cells: Hydrogenated Amorphous Silicon Solar Cell and Nano-quantum Dot Silicon Thin Film Solar Cell

    박막 실리콘 태양전지의 광열화현상 연구: 비정질 실리콘 태양전지 및 나노양자점 실리콘 박막 태양전지

    Ka-Hyun Kim

    김가현

    Light induced degradation is one of the major research challenges of hydrogenated amorphous silicon related thin film silicon solar cells. Amorphous silicon ... + READ MORE
    Light induced degradation is one of the major research challenges of hydrogenated amorphous silicon related thin film silicon solar cells. Amorphous silicon shows creation of metastable defect states, originating from elevated concentration of dangling bonds during light exposure. The metastable defect states work as recombination centers, and mostly affects quality of intrinsic layer in solar cells. In this paper we present results of light induced degradation in thin film silicon solar cells and discussion on physical origin, mechanism and practical solutions of light induced degradation in thin film silicon solar cells. In-situ light-soaking IV measurement techniques are presented. We also present thin film silicon material with silicon nano-quantum dots embedded within amorphous matrix, which shows superior stability during light-soaking. Our results suggest that solar cell using silicon nano-quantum dots in abosrber layer shows superior stability under light soaking, compared to the conventional amorphous silicon solar cell. - COLLAPSE
    February 2019
  • Research Article

    Spectroscopic Ellipsometry Measurement and Modeling of Hydrogenated Amorphous Silicon

    수소화된 비정질 실리콘의 타원편광분광분석 측정 및 모델링

    Ka-Hyun Kim

    김가현

    Spectroscopic ellipsometry is a powerful tool for analyzing optical properties of material. Ellipsometry measurement results is usually given by change of polarization ... + READ MORE
    Spectroscopic ellipsometry is a powerful tool for analyzing optical properties of material. Ellipsometry measurement results is usually given by change of polarization state of probe light, so the measured result should be properly treated and transformed to meaningful parameters by transformation and modeling of the measurement result. In case of hydrogenated amorphous silicon, Tauc-Lorentz dispersion is usually used to model the measured ellipsometry spectrum. In this paper, modeling of spectroscopic ellipsometry result of hydrogenated amorphous silicon using Tauc-Lorentz dispersion is discussed. - COLLAPSE
    February 2019
  • Research Article

    A Study on the Performance of 100 W Thermoelectric Power Generation Module for Solar Hot Water System

    태양열 온수 시스템에 적용 가능한 100 W급 열전발전 모듈 성능에 관한 연구

    Seo Ho-Young, Lee Kyung-Won, Yoon Jeong-Hun, Lee Soon-Hwan

    서호영, 이경원, 윤정훈, 이순환

    Solar hot water system produces hot water using solar energy. If it is not used effectively, overheating occurs during the summer. Therefore ... + READ MORE
    Solar hot water system produces hot water using solar energy. If it is not used effectively, overheating occurs during the summer. Therefore, a lot of research is being done to solve this. This study develops thermoelectric power module applicable to solar hot water system. A thermoelectric material can directly convert thermal energy into electrical energy without additional power generation devices. If there is a temperature difference between high and low temperature, it generate power by Seebeck effect. The thermoelectric module generates electricity using temperature differences through the heat exchange of hot and cold water. The water used for cooling is heated and stored as hot water as it passes through the module. It can prevent overheating of Solar hot water system while producing power. The thermoelectric module consists of one absorption and two radiation part. There path is designed in the form of a water jacket. As a result, a temperature of the absorption part was 134.2°C and the radiation part was 48.6°C. The temperature difference between the absorption and radiation was 85.6°C. Also, The Thermoelectric module produced about 122 W of irradiation at 708 W/m2. At this time, power generation efficiency was 2.62% and hot water conversion efficiency was 62.46%. - COLLAPSE
    February 2019
  • Research Article

    Effect of Plasma Enhancement on the Al-doped ZnO Thin Film Synthesis by MOCVD

    유기금속화학기상증착법에 의한 ZnO:Al 필름 합성에서 플라즈마 인가 효과

    Seomoon Kyu

    서문규

    Al-doped ZnO (AZO) thin films were synthesized on Si(100) wafers via plasma enhanced metal organic chemical vapor deposition (PE-MOCVD) method using ... + READ MORE
    Al-doped ZnO (AZO) thin films were synthesized on Si(100) wafers via plasma enhanced metal organic chemical vapor deposition (PE-MOCVD) method using diethyl zinc (DEZ) and N-methylpyrrolidine alane (MPA) as precursors. Effects of Al/Zn mixing ratio, plasma power on the surface morphology, crystal structure, and electrical property were investigated with SEM, XRD and 4-point probe measurement respectively. Growth rate of the film decreased slightly with increasing the Al/Zn mixing ratio, however electrical property was enhanced and resistivity of the film decreased greatly about 2 orders from 9.5×10-1 to 8.0×10-3 Ωcm when the Al/Zn mixing ratio varied from 0 to 9 mol%. XRD analysis showed that the grain size increased with increasing the Al/Zn mixing ratio. Growth rate and electrical property were enhanced in a mild plasma condition. Resistivity of AZO film decreased down to 7.0×10-4 Ωcm at an indirect plasma of 100 W condition which was enough value to use for the transparent conducting oxide (TCO) material. - COLLAPSE
    February 2019
  • Research Article

    The Observation and Interpretation of Long and Short Wave Radiation of the External Environment Surrounding a Single Building in the Summer

    하절기 단일건물 주변 외부공간의 장‧단파 복사관측과 해석

    Baek Chang-Hyeon, Choi Dong-Ho, Lee Bu-Yong, Lee In-Gyu

    백창현, 최동호, 이부용, 이인규

    In this study, we analyzed the relationship between four elements: long-wave radiation, the direction of the building, BVR (Building View Ratio), and ... + READ MORE
    In this study, we analyzed the relationship between four elements: long-wave radiation, the direction of the building, BVR (Building View Ratio), and cloud amount. We examined how long-wave radiations surrounding a building influences the perception of heat in the summer. The results are as follows. ① Long-wave radiation and BVR are highly correlated regardless of geographical direction. ② Especially, during dawn in a clear day, areas with high BVR observed high levels of long-wave radiation. ③ This correlation suggests that higher BVR in urban areas will result in a greater number of tropical nights. - COLLAPSE
    February 2019
  • Research Article

    Development of a Hybrid Power Generation System Using Photovoltaic Cells and Piezoelectric Materials

    태양 전지와 압전 재료를 이용한 하이브리드 발전시스템 개발

    Kim Yeongmin, Ahmed Rahate, Zeeshan, Chun Wongee

    김영민, Ahmed Rahate, Zeeshan, 천원기

    This paper deals with the operation of a hybrid power generation system made with photovoltaic cells and piezoelectric materials. The system can ... + READ MORE
    This paper deals with the operation of a hybrid power generation system made with photovoltaic cells and piezoelectric materials. The system can produce power from the wind as well as from the sun subject to their availability. Irrespective of the largeness of their power production, the power developed by both generators (i.e., phtovoltaic cells and piezoelectric cells) were combined and stored before it was applied to a load. Especially, the AC power (current) developed from each piezoelectric generator was converted by a full wave bridge rectifier and then combined prior to its storage in a capacitor. It was observed that the system can produce a maximum output power of 6.49 mW at loading resistance of 100 Ω. - COLLAPSE
    February 2019
  • Research Article

    A Case Study on the Islanding Detection Protection of PV System and ESS System

    태양광 발전과 ESS 시스템의 연계운전시 단독운전 방지 사례 연구

    Jong Rok Lim, Hye-Mi Hwang, Woo Gyun Shin, Young-Chul Ju, Young Seok Jung, Gi-Hwan Kang, Suk-Whan Ko

    임종록, 황혜미, 신우균, 주영철, 정영석, 강기환, 고석환

    BIPV or BAPV installation applied to building is increasing through public utility mandates enterprise. Solar PV energy generates only during the day ... + READ MORE
    BIPV or BAPV installation applied to building is increasing through public utility mandates enterprise. Solar PV energy generates only during the day, but if it is operated in convergence with ESS, which stores electrical energy, it can restrain the fossil energy used in buildings throughout the day. A solution is to converge with PV system and ESS. However, PV systems and ESS connected to the power grid in parallel can cause problems of electrical stability. A study was conducted on the case of failure to detect islanding operation under the parallel operation of PV generation and ESS that are connected in parallel to power grid. Experiments conducted various non-islanding detections under the operating conditions. In the experiment results, when one PCS - PV inverter or ESS inverter - was operating under the islanding condition, it stopped working within 0.5 seconds of the Korean grid standard. However, when both of PV inverter and ESS inverter were operating at the same time under the islanding situation, the anti-islanding algorithm did not operate normally and both inverters continuously supplied power to the connected RLC loads. islanding detection Algorithm developed by each inverter manufacturer has caused this phenomenon. Therefore, this paper presented a new test standard for islanding detection. - COLLAPSE
    February 2019
  • Research Article

    Analysis on the Effect of Local Climate on the Unit-type Ground Heat Exchanger

    지역 기후가 유닛형 지중열교환기 성능에 미치는 영향

    Bae Sangmu, Kim Jae-Min, Nam Yujin

    배상무, 김재민, 남유진

    A ground source heat pump (GSHP) system can stable system operation by using underground heat source and has high reliability for energy ... + READ MORE
    A ground source heat pump (GSHP) system can stable system operation by using underground heat source and has high reliability for energy production. However, wide-spread of the GSHP system is delayed to high initial investment costs. In previous studies, horizontal and unit-type ground heat exchanger (GHX) have developed to overcome disadvantages such as high initial cost. However, these performances of GHXs are greatly influenced by climate and weather conditions. It is necessary to analyze the performance of GHX according to the ground temperature change in the installation site. In this study, the ground temperature of each installation site confirmed and performance of unit-type GHX quantitatively analyzed by numerical analysis. As the result, the performance of the unit type GHX was 33.9 W/m in Seoul, 34.2 W/m in Daejeon, and 37.2 W/m in Busan.The result showed the difference performance of GHX according to local climate was maximum of 9.7%. - COLLAPSE
    February 2019
  • Research Article

    Research on the Heat Transfer and Pressure Drop by Installation Conditions of Rectangular Obstacle in a Solar Air Heater Based on CFD

    CFD를 활용한 태양열 공기가열기 내 사각저항체 설치 조건에 따른 열전달 및 압력강하에 관한 연구

    Choi Hwi-Ung, Kim Young-Bok, Yoon Jung-In, Son Chang-Hyo, Choi Kwang-Hwan

    최휘웅, 김영복, 손창효, 윤정인, 최광환

    The solar air heater has various performances according to an obstacle installed in the air duct. Many studies on thermal performance have ... + READ MORE
    The solar air heater has various performances according to an obstacle installed in the air duct. Many studies on thermal performance have been conducted. But many of these studies were using a kind of rib type obstacle attached at the bottom of absorbing plate, but they are so hard to be manufactured. In this study, characteristics of the heat transfer and pressure drop in the solar air heater with various horizontal rectangular obstacles was investigated by CFD (Computational Fluid Dynamics) analysis. As a result, the heat transfer performance was improved from 1.2 to 3.32 times depending on installation conditions of rectangular obstacle. The pressure drop, however, also increased with increment of heat transfer performance from 2.8 to 180 times only by changing installation conditions of rectangular obstacle. Thus, the performance factor presenting the thermal performance enhancement on the same pressure drop was also confirmed. As a result, the highest value of 0.828 as better performance factor was obtained at the lower height of rectangular obstacle and this value has started to decrease with increment of heat transfer performance. In the end, it could be confirmed that the pressure drop was carried higher than the quantity of improvement of the heat transfer performance when the heat transfer performance was increased by change of installation conditions of rectangular obstacle. Both heat transfer enhancement and pressure drop to be required for system need to be considered before the rectangular obstacles are applied to the solar air heater. - COLLAPSE
    February 2019