• Journal of Power Electronics
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• 제17권6호
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• pp.1600-1610
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• 2017

We propose maximum power extraction from a rooftop solar photovoltaic (PV) array during partial shading conditions. Partial shading is unavoidable during power extraction from rooftop PV systems due to nearby tall buildings (construction of additional floors) and trees (growth of trees). Many reconfiguration techniques can be used to extract maximum power in partial shading conditions, but in several cases, the real maximum power output is not achieved. In this study, a new switched PV technique is proposed to enhance the power output. The proposed technique is simple to use and more cost effective than other reconfiguration techniques. Therefore, it is suitable for rooftop applications. The power output of the proposed technique is compared with that of existing techniques with similar shading patterns. Eight panels with ratings of 250 watts (2 kW) each are used for testing. MATLAB simulation and hardware verification are done for the proposed and existing techniques. The proposed technique is implemented on a $4{\times}2$ PV array, although it can be extended to a number of arrays.

• 국제학술발표논문집
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• The 9th International Conference on Construction Engineering and Project Management
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• pp.937-944
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• 2022

Electric vehicles (EVs) have been growing to reduce energy consumption and greenhouse gas (GHG) emissions in the transportation sector. The increasing number of EVs requires adequate recharging infrastructure, and at the same time, adopts low- or zero-emission electricity production because the GHG emissions are highly dependent on primary sources of electricity production. Although previous research has studied solar photovoltaic (PV) -integrated EV charging stations, it is challenging to optimize spatial areas between where the charging stations are required and where the renewable energy sources (i.e., solar photovoltaic (PV)) are accessible. Therefore, the primary objective of this research is to support decisions of siting EV charging stations using a spatial data clustering method integrated with Geographic Information System (GIS). This research explores spatial relationships of PV power outputs (i.e., supply) and traffic flow (i.e., demand) and tests a community in the state of Indiana, USA for optimal sitting of EV charging stations. Under the assumption that EV charging stations should be placed where the potential electricity production and traffic flow are high to match supply and demand, this research identified three areas for installing EV charging stations powered by rooftop PV in the study area. The proposed strategies will drive the transition of existing energy infrastructure into decentralized power systems. This research will ultimately contribute to enhancing economic efficiency and environmental sustainability by enabling significant reductions in electricity distribution loss and GHG emissions driven by transportation energy.

• KIEAE Journal
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• 제15권1호
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• pp.89-95
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• 2015

The centralized power supply system and rainwater treatment system, which are major infrastructure in modern cities, are showing their limitations in accommodating environment load due to climate changes that has aggravated recently. As a result, complex issues such as shortage of reserve power and urban flooding have emerged. As a single solution, decentralized systems such as a model integrating photovoltaic system and rooftop greening system are suggested. When these two systems are integrated and applied together, the synergy effect is expected as the rooftop greening has an effect of preventing urban flooding by controlling peak outflow and also reduces ambient temperature and thus the surface temperature of solar cells is lowered and power generation efficiency is improved. This study aims to compare and analyze the monitoring results of four algorithms that define correlations between micro-climate variables around rooftop greening and the surface temperature of solar cells and generate their significance. By doing so, this study seeks to present an effective algorithm that can estimate the surface temperature of solar cell that has direct impact on the efficiency of photovoltaic power generation by observing climate variables.

• 대한건축학회논문집:구조계
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• 제35권5호
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• pp.169-179
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• 2019

During the initial design stage of apartment complex, the photovoltaic(PV) system has been considered as an alternative of renewable energy system and planned to install at the rooftop floor level in general. The electric power generation characteristics can be influenced by the block layout, building orientation and roof top structure because of azimuth angle, tilt angle, and partial shading. This study aims to investigate power generation characteristics of photovoltaic system in apartment buildings by considering the partial shading conditions due to the block layout, building orientation and roof-top structures. For the photovoltaic module arrangement planning in rooftop floor level, shading areas were firstly analyzed due to the adjacent building structure. And the annual and seasonal power generation of PV system were analyzed through the PVsyst simulation results. The results show that shading period at the roof top surface can be increased due to the parapet and water tank. Initial design power capacity can be decreased by considering the daily insolation period and distance between PV modules through the shading simulation. As the number of PV modules decreases, the annual power generation can be decreased. However annual power generation per unit area of PV modules can be increased and performance ratio can be increased above 80%. Also the power generation of PV system can be critically affected by building orientation and the performance ratio can be drastically decreased in east-oriented buildings due to the shading problems caused by adjacent structures at roof top level such as parapet and water tank.

• Advances in Energy Research
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• 제2권1호
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• pp.11-20
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• 2014

This paper examines the climatic and technical feasibilities of zero energy buildings in Seoul, Shanghai, Singapore and Riyadh. Annual and seasonal energy demands of office buildings of various scales in the above cities were compared. Using optimally tilted rooftop PV panels, solar energy production potentials of the buildings were estimated. Based on the estimates of onsite renewable energy production and building energy consumption, the energy self-sufficiencies of the test buildings were assessed. The economic feasibilities of the PV systems in the four locations were analyzed. Strategies for achieving zero energy buildings are suggested.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.59.2-59.2
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• 2011

This study presents a new method for coupling ArcGIS (popular GIS software) with TRaNsient SYstems Simulation (TRNSYS, reference software for researchers and engineers around the world) to use capabilities of the 4 and 5-parameter PV array performance models within the ArcGIS environment. Using the validated and industry-proven solar energy simulation models implemented in TRNSYS and other built-in ArcGIS functionalities, dynamic characteristics of distributed PV potential in terms of hourly, daily or monthly power outputs can be investigated with considerations of diverse options in selecting and mounting PV panels. In addition, the proposed method allows users to complete entire procedures in a single framework (i.e., a preliminary site survey using 3D building models, shading analyses to investigate usable rooftop areas with considerations of different sizes and shapes of buildings, dynamic energy simulation to examine the performances of various PV systems, visualization of the simulation results to understand spatially and temporally distributed patterns of PV potential). Therefore tedious tasks for data conversion among multiple softwares can be significantly reduced or eliminated. While the programming environment of TRNSYS is proprietary, the redistributable executable, simulation kernel and simulation engine of TRNSYS can be freely distributed to end-users. Therefore, GIS users who do not have a license of TRNSYS can also use the functionalities of solar energy simulation models within ArcGIS.

• 교육시설
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• 제11권5호
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• pp.14-23
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• 2004

Building-integrated photovoltaic(BIPV) systems can operate as a multi-functional building components, which generates electricity and serves as part of building envelope. It can be regarded as a new architectural elements, adding to the building's aesthetics. Besides of these benefits, the application of PV systems into school buildings tends to play an important role in energy education to students. In this context, this study aims to analyse the applicability of PV systems into school buildings. For an existing school building, four types of BIPV designs were developed; rooftops, wall-attached, wall-mounted with angle, and sunshading device. Based on energy modeling of those BIPV systems, the whole 60.1kWp rated PV installation is expected to yield about 65.6MWh of electricity, that is about 50% more than the annual electricity consumption of the school, 44MWh. It was also found that the applicability of the PV systems into the school building was very high, and the rooftop systems with the optimized angle was the most efficient in energy production, followed by sunshading, wall-mounted with angle and wall-attached. It concludes that school buildings have a reasonable potential to apply PV systems in the aspects of building elements and electricity production.

• 조명전기설비학회논문지
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• 제23권1호
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• pp.162-168
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• 2009

본 논문에서는 태양전지를 가지고 일정량의 태양광으로부터 최대 유효전력을 얻기 위해 고정식 태양광 발전시스템과 태양 위치추적기를 부착한 태양광 발전시스템에서 PV모듈의 각도 변화 및 어레이 간격에 따른 최적의 발전효율에 대한 연구 및 실험을 하였다. 먼저, PV 모듈의 다양한 각도를 가지고 실험한 결과 PV 모듈 경사각 30[$^{\circ}$]에서 측정한 결과 값이 경사각 20[$^{\circ}$] 및 40[$^{\circ}$]일 때보다 발전 효율이 $12{\sim}17$[%] 상승되었다. 그러므로 본 논문의 연구 결과에서는 태양광 발전시스템의 실용화 측면에서 PV 모듈의 경사각 30[$^{\circ}$] 설치를 하여 발전을 하는 것이 가장 좋은 변환 효율을 얻을 수 있었다. 하지만 태양전지를 지붕 및 옥상에 설치를 할 경우, 면적 활용이 좁고 겨울에 눈이 쌓이게 될 경우에는 경사각에 의해 빠르게 쓸려 내려갈 수 있도록 경사각을 35[$^{\circ}$]로 선정하는 것이 타당하다.

• 전기학회논문지
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• 제66권12호
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• pp.1905-1912
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• 2017

In recent years, Ulaanbaatar, a capital of Mongolia has witnessed major problem that air quality reaches hazardous level during the winter season. Coal combustion for heating of every house in "Ger" district is main reason. One way to reduce the air pollution is mass usage of electric heater. However, there are several difficulties such as overload and degradation of transformers and other equipment used in distribution and transmission systems as well as power shortage occurrence in evening peak period due to residential consumption. This study aims to contribute for solving the air pollution and power shortage problem in Mongolia. One possible solution could be distributed generation (DG) with photovoltaic (PV) penetration. In this study, PV with energy storage (ES) hybrid system to reduce peak load is analyzed. We proposed the suitable structure of PV-ES hybrid for Mongolian household, and suggested several operation scenarios. Optimal operation algorithm is carried out based on a comparison aspect from economical, grid impact and PV penetration possibility. The economic analyse shows annual income of 520USD, and has a payback period of 8 years for selected scenario. The proposed PV-ES system structure is verified by experimentation set on the building rooftop in city center. The suggested scenario is planned to apply for system in further research.

• Journal of Power Electronics
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• 제19권4호
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• pp.881-893
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• 2019

This paper proposes a practical sliding-mode controller design for shaping the impedances of cascaded boost-converter power decoupling circuits for reducing the second order harmonic ripple in photovoltaic (PV) current. The cascaded double-boost converter, when used as power decoupling circuit, has some advantages in terms of a high step-up voltage-ratio, a small number of switches and a better efficiency when compared to conventional topologies. From these features, it can be seen that this topology is suitable for residential (PV) rooftop systems. However, a robust controller design capable of rejecting double frequency inverter ripple from passing to the (PV) source is a challenge. The design constraints are related to the principle of the impedance-shaping technique to maximize the output impedance of the input-side boost converter, to block the double frequency PV current ripple component, and to prevent it from passing to the source without degrading the system dynamic responses. The design has a small recovery time in the presence of transients with a low overshoot or undershoot. Moreover, the proposed controller ensures that the ripple component swings freely within a voltage-gap between the (PV) and the DC-link voltages by the small capacitance of the auxiliary DC-link for electrolytic-capacitor elimination. The second boost controls the main DC-link voltage tightly within a satisfactory ripple range. The inverter controller performs maximum power point tracking (MPPT) for the input voltage source using ripple correlation control (RCC). The robustness of the proposed control was verified by varying system parameters under different load conditions. Finally, the proposed controller was verified by simulation and experimental results.