• Research Article

    Design Optimization of Large-scale Bifacial Photovoltaic Module Frame Based on FEM and RSM

    유한요소법 및 반응표면법 기반 대면적 양면형 태양광 모듈 프레임 최적설계

    Dongwoon Han, Seongtak Kim

    한동운, 김성탁

    Large-scale bifacial photovoltaic modules have the advantages of high unit yield and production. Because the module weight increases with the module size, … + READ MORE
    Large-scale bifacial photovoltaic modules have the advantages of high unit yield and production. Because the module weight increases with the module size, the power conversion efficiency can decrease owing to defects such as encapsulant delamination and cell cracking caused by the increased deflection of the module. However, research on the design optimization of large-scale bifacial photovoltaic module frames is lacking. Therefore, in this study, we analyzed the deflection of large-scale bifacial photovoltaic modules using finite element analysis (FEA). Furthermore, we propose an optimal design for a solar module frame that minimizes both module deflection and frame weight using the response surface methodology (RSM). We established 32 experimental setups utilizing the design of experiments with five frame shape factors placed at two levels each. The results of structural analysis showed that the maximum deflection occurred at the center of the module. The results obtained using RSM for minimizing deflection and weight yielded optimal factors as follows: a, b, c, d, e were found to be 1.9 mm, 14.0 mm, 1.5 mm, 1.7 mm, and 2.5 mm, respectively. A comparison of the deflection and weight between the existing and optimal conditions obtained from structural analysis revealed an increase in weight of approximately 4.5% compared to the existing conditions. Simultaneously, a deflection reduction of approximately 15.8% was observed. - COLLAPSE
    30 December 2023
  • Research Article

    A Methodology for Calculating the Limit Capacity of Solar Power Generation Considering Power Generation System and Transmission Capacity

    발전시스템 및 송전용량을 고려한 태양광 발전 한계투입용량 산정 방법론

    Yong-Ha Kim, Yu-ri Kim, Gyu-Rim Han

    김용하, 김유리, 한규림

    To achieve carbon neutrality, the proportion of renewable energy must increase according to the 2030 implementation plan. However, the stability of the … + READ MORE
    To achieve carbon neutrality, the proportion of renewable energy must increase according to the 2030 implementation plan. However, the stability of the power supply is reduced owing to the output volatility of renewable energy. To ensure a high power quality, the system must operate stably. Therefore, only as much variable renewable energy as the system can accommodate should be input. In this study, we developed a methodology to calculate the limit input capacity of solar power generation by considering the power generation and transmission systems. For the power generation system, the minimum constraints of power generation capacity and secondary reserve power were considered. Additionally, line capacity constraints were considered for the transmission system. In other words, a methodology was developed to calculate the limit input capacity of solar power generation that satisfies the three constraints. - COLLAPSE
    30 December 2023
  • Research Article

    Power Generation Simulation for Photovoltaic Device Using Ray Tracing

    Ray Tracing 기법을 이용한 태양광 발전량 시뮬레이션

    Hyejin Park, Myunghun Shin

    박혜진, 신명훈

    Recently, with the increase in regulations on self-power generation of energy in buildings, building-integrated photovoltaic systems (BIPV), that is, solar power on … + READ MORE
    Recently, with the increase in regulations on self-power generation of energy in buildings, building-integrated photovoltaic systems (BIPV), that is, solar power on the outer walls of buildings, are also on the rise. Thus, considering the shadow of a building, the power generation of an elevated solar cell module according to differences in location, shadow, and reflectance (albedo) must be analyzed. In this study, we used a ray-tracing method and a three-dimensional (3D) optical design simulation program. For ray-tracing simulation, we produced sophisticated structures and provided optical properties, and a correction process for the surface temperature was conducted using a temperature correction formula. In addition, the characteristics and accuracy of the simulation were compared using Solar Pro data. Finally, in this study, we report the amount of power generated according to differences in location, shade, and reflectance (albedo). - COLLAPSE
    30 December 2023
  • Research Article

    Analysis of Building Energy Efficiency Rating for Old Public Buildings according to the On-site Investigation Results

    노후 공공건축물의 현장 조사 결과에 따른 에너지효율등급 평가 결과 분석

    Minjung Bae, Hosang Ahn, Jaesik Kang

    배민정, 안호상, 강재식

    The building energy efficiency grade of old buildings in Korea is rated according to criteria of building energy performance calculated by the … + READ MORE
    The building energy efficiency grade of old buildings in Korea is rated according to criteria of building energy performance calculated by the ECO2 energy simulation program. To evaluate this performance, ECO2 input data are required, which influence both the intermediate decision process and final calculation results. However, the required input data collection of old buildings for ECO2 simulation is not as simple as expected, and is more difficult than that for new buildings because of many unrecorded changes and updates after the original construction. In these aspects, certification assessment documents for old public buildings are not suitable for preparing input data for ECO2 and usually do not reflect the actual status and condition of buildings from either passive or active perspectives. Therefore, in this study, an ECO2 building energy simulation was performed for 41 old public buildings to examine how input data differences from on-site audits can induce differences in both the simulation process and results. The error range of the primary energy consumption for grades extended from 0 to 231.9 kWh/m2․yr, depending on whether on-site audit results are considered or not. Because of the long operation period of old public buildings, the initial design plan and current operation status have changed significantly, and our suggestion is that the confirmation step for collecting input data for old public buildings must be a prerequisite and an essential aspect for on-site investigation based on ECO2 simulation. - COLLAPSE
    30 December 2023
  • Research Article

    Development of Optimal Operation for District Heating and Cooling Facility Considering P2H

    P2H를 고려한 집단에너지사업자의 최적운영 알고리즘 개발

    Yong-Ha Kim, Yu-ri Kim, Gyu-Rim Han

    김용하, 김유리, 한규림

    As the supply of renewable energy increases, instability problems in power systems arise because of the output volatility and intermittency of renewable … + READ MORE
    As the supply of renewable energy increases, instability problems in power systems arise because of the output volatility and intermittency of renewable energy. Sector coupling has recently emerged as a solution to renewable energy problems. Therefore, in this study, P2H, which converts power into heat during sector coupling, was considered. Considering P2H in district cooling and heating systems, an optimal operation algorithm for district heating and cooling facilities was developed. The operating characteristics of district energy heat source facilities were considered to maximize profits, and economical heat storage tank operation was also considered for P2H. In addition, useful information for introducing P2H was derived through a sensitivity analysis to ensure economic feasibility for district cooling and heating business operators when P2H was implemented. - COLLAPSE
    30 December 2023
  • Research Article

    Prediction Model For Colored BIPV Modules

    Color BIPV 모듈 성능 예측을 위한 모델 분석

    Yeon-Bae Shin, Gyu-Gwang Kim, Yong-Hyun Cho, Young-Ho Cho, Tae-Youl Yang

    신연배, 김규광, 조용현, 조영호, 양태열

    Adding various colors to photovoltaic (PV) modules is essential for the building-integrated photovoltaics (BIPV) market; however, it can also reduce PV performance … + READ MORE
    Adding various colors to photovoltaic (PV) modules is essential for the building-integrated photovoltaics (BIPV) market; however, it can also reduce PV performance and increase manufacturing costs. Therefore, a tool is required to predict PV performance based on color before production of PV modules. In this study, we demonstrate an approach for predicting the performance of colored PV modules before they are produced. First, we analyzed the optical properties of various colors of polyvinyl chloride (PVC) films available in the market and their correlation with power. A total of 15 prediction models were trained. Then, we manufactured colored films for BIPV, predicted their power using the trained models, and compared the predictions with actual power values. Additionally, we validated and optimized the prediction models using mean absolute error (MAE) and root mean squared error (RMSE). We achieved a low MAE of 3.8% and an RMSE of 4.3% using a prediction model formula that consisted of transmittance or a combination of transmittance and absorption. This approach offers several advantages, such as the ability to predict the performance based solely on the optical properties of front-colored films or glass used in colored BIPV without the need for sample production, which can save time and resources. - COLLAPSE
    30 December 2023
  • Research Article

    A Study on Improving the Stability of Perovskite Solar Cells through 2D/3D Stacked Thin Films

    2D/3D 적층 박막을 통한 페로브스카이트 태양전지의 안정성 향상 연구

    Won-Gyu Choi, Jae-Seong Jeong

    최원규, 정재성

    Organic-inorganic perovskite solar cells, which feature remarkable electrical and optical characteristics, are the most promising candidates for next-generation photovoltaic materials. However, their … + READ MORE
    Organic-inorganic perovskite solar cells, which feature remarkable electrical and optical characteristics, are the most promising candidates for next-generation photovoltaic materials. However, their commercial applications are limited owing to the instability of perovskite. In this context, we conducted a study to improve the stability of perovskite using 2D/3D stacked thin films. We deposited 2D BA2PbI4 (BA = butylammonium) perovskite on the surface of 3D FAPbI3 (FA = formamidinium) perovskite via plane growth resulting in the formation of clear 2D/3D stacked thin films. The introduction of 2D perovskite leads to improved device performance and stability because defect-induced non-radiative recombination and thin-film degradation are suppressed. - COLLAPSE
    30 December 2023
  • Research Article

    Transformer-Based Photovoltaic Power Prediction Model Utilizing Multiple Weather Forecasts

    다중 기상 예보를 활용한 트랜스포머 기반 태양광 발전량 예측 모델

    Jae Min Park, Dong Woo Lee, Kun Joe, Hyo-Seon Yoon

    박재민, 이동우, 조건, 윤효선

    Given multiple weather forecasts, how can we achieve higher photovoltaic (PV) prediction accuracy while maintaining prediction stability? As the significance of renewable … + READ MORE
    Given multiple weather forecasts, how can we achieve higher photovoltaic (PV) prediction accuracy while maintaining prediction stability? As the significance of renewable energy sources increases, accurate prediction of PV generation has become increasingly important. However, the inherent volatility of the weather sets a challenge into achieving accurate PV generation predictions. To address this challenge, this study proposes a Transformer-based Photovoltaic power prediction model Utilizing multiple weather forecasts (TPU), which is a novel framework that utilizes multiple weather forecasts to enhance prediction accuracy while maintaining performance stability. TPU employs attentive Long Short-Term Memory (LSTM) to create embeddings of weather forecasts with different time horizons and cross-attention to fuse the features of different forecasts. Experimental results conducted using a six-month dataset comprising generation data from nine PV power plants spread across the whole country demonstrate that our model outperforms all baseline models in terms of mean absolute error (MAE) and root mean squared error (RMSE), while concurrently achieving a reduced mean absolute deviation (MAD). - COLLAPSE
    30 December 2023
  • Research Article

    Design and Application of ITO/Ag/ITO/Ag/ITO Multilayer Structure with Effective Control of Electromagnetic Wave Function

    고기능성 파장 제어 기능을 가지는 ITO/Ag/ITO/Ag/ITO 다층구조의 설계와 응용 방안

    Youngwoong Ju, Chanhyuk Choi, Hyeji Kim, Junghyun Lee, Yeonwoo Choi, Juhyung Yun, Joondong Kim

    주영웅, 최찬혁, 김혜지, 이정현, 최연우, 윤주형, 김준동

    Effective control of electromagnetic waves is critical for efficient energy utilization and other relevant applications. In particular, the active management of long-wavelength … + READ MORE
    Effective control of electromagnetic waves is critical for efficient energy utilization and other relevant applications. In particular, the active management of long-wavelength infrared (IR) radiation would be useful in energy conservation and military defense. Herein, we propose an efficient approach to control the electromagnetic waves of light by suppressing the short wavelength range of UV light and long wavelength range of IR light while maintaining visual transparency to human eyes. For effective infrared control, we propose an OMOMO (oxide/metal/oxide/metal/oxide) structure in which metal oxides and metal layers are deposited on an OMO (oxide/metal/oxide) structure. The novel hybrid structure of metal and metal-oxide films are alternated to form multiple ITO/Ag/ITO/Ag/ITO interfaces. To confirm the features of the IR control interface, the optical and electrical properties were investigated in terms of transmittance, reflectance resistance, and electromagnetic interface (EMI) shielding efficiency. The ITO/Ag/ITO/Ag/ITO multilayer structure exhibited an excellent optical transmittance of 65.43% and substantial reflectance of 94.02% at long wavelengths. The overall EMI shielding was highly effective, reaching 40.59 dB. This suggests that functional transparent films can be adopted in military, energy, and transparent device applications. - COLLAPSE
    30 December 2023
  • Research Article

    Evaluation of Back-side Temperature Behaviors and Power Generation Performance for Vertical Wall-type BIPV System

    수직 외벽형 BIPV 시스템의 후면 온도특성 및 발전성능 평가 연구

    Hyun-Kyu Choi, Eun-Ho Kang, Mun-Gyu Choi, Dong-Su Kim, Jong-Ho Yoon

    최현규, 강은호, 최문규, 김동수, 윤종호

    As in other photovoltaic systems, an increase in module temperature leads to a reduction in performance in the building integrated photovoltaic (BIPV) … + READ MORE
    As in other photovoltaic systems, an increase in module temperature leads to a reduction in performance in the building integrated photovoltaic (BIPV) system. Therefore, BIPV designers must consider the temperature characteristics of the BIPV at the design stage, and this needs to be reviewed based on long-term data. However, because most previous studies were conducted in the short term under specific weather conditions, it is difficult to obtain basic data on long-term performance. For this reason, this study aimed to provide basic data based on the domestic typical meteorological year by using a simulation for a vertical exterior wall-type BIPV system. The research method was as follows: (i) collect necessary data from the field-installed BIPV system, (ii) establish and verify the simulation model based on the measurement data, and (iii) calculate annual data of the vertical BIPV system using the simulation model. As a result of the study, the surface temperature range, which accounts for 90% of the power generation time under the weather conditions in Daejeon, was 2.5℃ ~ 42.0℃ under ventilator open conditions and 4.7℃ ~ 47.5℃ under ventilated closed conditions. Accordingly, the reduction in module efficiency attributable to temperature increase was as high as 7.2% in the ventilator open condition and 9.6% in the ventilated closed condition. Due to this temperature difference, the power generation difference was as high as about 2% in the winter when vertical solar radiation was high. In the summer, the difference was 1% ~ 1.5%. - COLLAPSE
    30 December 2023
  • Research Article

    Variations in Indoor Radon Concentrations Influenced by Airtightness Performance and Existing Facilities in an Apartment House

    공동주택의 기밀성능 및 기존 설비에 따른 실내 라돈 농도 변화

    Jinhee Jeong, Yun Gyu Lee

    정진희, 이윤규

    Among various indoor air pollutants, radon is a ubiquitous and imperceptible substance that has long-term harmful effects on the human body; however, … + READ MORE
    Among various indoor air pollutants, radon is a ubiquitous and imperceptible substance that has long-term harmful effects on the human body; however, it can be effectively removed through indoor/outdoor air exchange. In this study, we collected data on the variations in indoor radon levels caused by airtightness performance, window opening, and bathroom exhaust fan operation. The levels of indoor radon fluctuated more irregularly in less airtight conditions, while the highest concentrations were observed in an apartment house with good airtightness performance (<1.5 ACH50). Opening the windows to allow for cross ventilation during the first hour of the experiment significantly increased the removal efficiency. The percentage of removal increases as the size of the window opening increases. Nevertheless, accidental variations in ventilation volumes brought on by weather-related factors, such as wind, temperature, and air pressure, makes this unmaintainable. The indoor radon levels of the entire apartment house did not significantly change when the bathroom exhaust fan was operating. Smaller areas, such as a single bedroom, can have their indoor radon concentrations reduced to less than 100 Bq/m3. This implies that in situations where the ventilation system is inadequate, the bathroom exhaust fan can function as a substitute instrument. - COLLAPSE
    30 December 2023
  • Research Article

    A Study on the Properties of Encapsulants to Enhance the Flame Retardant Properties of BIPV Modules

    건물일체형 태양광 모듈의 난연 특성 강화를 위한 난연 봉지재 특성 연구

    Suhwan Kim, Sung Ju Tark, Kyewon Park, Jongsung Park

    김수환, 탁성주, 박계원, 박종성

    This study examined the flame-retardant properties of several encapsulant types that could replace existing ethylene vinyl acetate to improve the fire safety … + READ MORE
    This study examined the flame-retardant properties of several encapsulant types that could replace existing ethylene vinyl acetate to improve the fire safety of Building Integrated Photovoltaic modules when used as exterior building material. For the study, six types of films (flame-retardant polyethylene terephthalate, polyether ether ketone, flame-retardant polyethylene naphthalate, polyimide, polyethylene, and thermoplastic polyurethane) were prepared, and various analyses were performed to determine the fire stability of each film. Thermogravimetric Analyzer results showed that polyimide and polyether ether ketone films had the best thermal stability. Upon measuring the light transmittance, polyimide and polyethylene demonstrated >90% light transmittance. The water vapor transmission rate value for the 50 μm-thick polyimide was 270 g/m2/day. Polyimide film did not ignite during the cone calorimeter measurement; instead, only film shrinkage was observed. Collectively, polyimide showed the best thermal stability and module application characteristics among all six types of films. - COLLAPSE
    30 December 2023
  • Research Article

    Cost and Benefits of Replacing Illegal Canopies with Solar Panels

    불법건축물 요소의 태양광발전 설비화에 따른 비용편익분석

    Sungsu Kim, Jeongcheol Lee, Jongyeon Lim

    김성수, 이정철, 임종연

    When performing green remodeling of public buildings, illegal buildings are demolished, and these illegal buildings installed for user convenience incur demolition costs. … + READ MORE
    When performing green remodeling of public buildings, illegal buildings are demolished, and these illegal buildings installed for user convenience incur demolition costs. However, there is a way to legalize illegal buildings to increase the installation of renewable energy while saving demolition costs. In this study, the cost of replacing an illegal canopy with solar panels and the effect of reducing the primary energy demand were analyzed. As a result, converting the demolition cost of illegal buildings to the expense of installing solar panels is expected to contribute to cost-effective green remodeling, maintenance of user convenience, and an improved supply of new and renewable energy. - COLLAPSE
    30 December 2023
  • Research Article

    Fire Performance Analysis of Building Integrated Solar System Roofs

    건물 일체형 태양광 발전시스템(BIPV) 지붕의 화재 성능 분석

    Jin-Hwan Jeong, Won-Seok Choi, Hyung-Min Seo, Bo-Hyuk Lim

    정진환, 최원석, 서형민, 임보혁

    Currently, fire tests for building integrated solar modules and fire tests for roof materials are managed separately. Thus, it is necessary to … + READ MORE
    Currently, fire tests for building integrated solar modules and fire tests for roof materials are managed separately. Thus, it is necessary to establish an appropriate test method for a building integrated photovoltaic (BIPV) system for the roof because the roof BIPV system has both of these characteristics, i.e., solar modules and building materials. In this research, two types of roof BIPV systems (with solar modules, without solar modules) were tested and analyzed for their fire performance, respectively. Fire tests were conducted based on KS F2257-1 and KS F2257-5. The results showed that the system with the module has weaker fire resistance performance than the system without it. - COLLAPSE
    30 December 2023
  • Research Article

    Development and Performance Analysis of an Air Source Heat Pump Outdoor Unit Heating System with Photovoltaic Thermal Modules

    태양광열 복합 모듈을 활용한 공기열원 히트펌프 실외기 가열 시스템 개발

    Hong-Jin Joo, Young-Sub An, Kyoung-Ho Lee

    주홍진, 안영섭, 이경호

    In this study, a convergence technology that can be linked with photovoltaic thermal (PVT) modules was derived to increase the performance and … + READ MORE
    In this study, a convergence technology that can be linked with photovoltaic thermal (PVT) modules was derived to increase the performance and efficiency of air source heat pumps that are currently most widely used as cooling, heating, and domestic hot water supply equipment in public buildings. The solar energy and air source heat pump convergence technology developed through this study was an indirect supply type outdoor unit heating system that supplied heat energy acquired through a PVT module by increasing the temperature of the air flowing into the outdoor unit when the heat pump heating mode was operating. A bench-scale test device was designed and manufactured to verify the performance of the outdoor unit heating system of an air source heat pump using a PVT module. The performance evaluation confirmed that the heating performance of the air source heat pump was improved compared with that of the conventional air source heat pump without the heating system under the same test conditions. In addition, the heating demonstration was performed by applying the air source heat pump outdoor unit heating system using a PVT module to the air source heat pump installed at the Seodaemun Fire Station Hongeun 119 Safety Center, where an actual public building was remodeled. Consequently, the air source heat pump was heated. The analysis revealed that COP increased by more than 0.5. - COLLAPSE
    30 December 2023
  • Research Article

    Voltage – Current Curve Simulation Using the Environmental Data and Artificial Intelligence Fault Diagnosis Method for PV Strings

    환경데이터 기반 전압-전류 곡선 시뮬레이션 및 태양광 스트링 인공지능 고장진단 방법

    Suk Whan Ko, Woo Gyun Shin, Young Chul Ju, Hye Mi Hwang, Ki Ho Son, Han Gi Kim, Ui Seong Choi

    고석환, 신우균, 주영철, 황혜미, 손기호, 김한기, 최의성

    This paper focuses on the development and analysis of a solar photovoltaic (PV) combiner box equipped with a module capable of obtaining … + READ MORE
    This paper focuses on the development and analysis of a solar photovoltaic (PV) combiner box equipped with a module capable of obtaining Voltage–Current (I-V) characteristic curves to evaluate the performance degradation and faults in a solar power plant. A deep learning algorithm was proposed for the analysis of I-V curves. Direct Current circuit breakers were applied to obtain the I-V curves of each string circuit inside the combiner box. The fault dataset was labeled through classification based on the shape of I-V characteristic curves. The fault data were directly collected through field diagnosis at the power plant, amounting to a dataset of 3,200. A GoogLeNet transfer deep learning model with a convolution neural network (CNN) was used to develop a fault diagnosis algorithm, achieving training and validation accuracies of more than 95%. Empirical research was conducted at a 1.5 MW solar power plant site. Shading and bypass diode short-circuit faults were simulated in solar PV strings to evaluate the accuracy of the algorithm. The artificial intelligence algorithm demonstrated accuracy rates of 98.67% for shading simulation and 95.06% for bypass diode short-circuit fault simulation. - COLLAPSE
    30 December 2023