Digital elevation model-based convolutional neural network modeling for searching of high solar energy regions

Heo, Jae,Jung, Jaehoon,Kim, Byungil,Han, SangUk Elsevier 2020 APPLIED ENERGY Vol.262 No.-

<P><B>Abstract</B></P> <P>The prediction of potential solar energy at candidate sites plays a key role in the search for high solar energy regions to accommodate solar photovoltaic facilities. However, the estimation of solar irradiation can be inaccurate when site conditions are not similar to the ones at observation stations. In particular, regional effects caused by adjacent terrains have rarely been modeled in the estimation process. This study thus presents a digital elevation map-based convolutional neural network modeling method for the prediction of annual solar irradiation under clear-sky conditions. Using map data as an input, the sole impact of neighboring topography on available solar energy can be understood at a large scale. Specifically, with elevation maps and corresponding solar irradiation maps, the mean of solar irradiation values for each map is calculated. This mean value is then used as an output to identify the non-linear and hidden relationship between such values and the input maps in training processes. The proposed network model uses terrain map datasets and hence enables the recognition and learning of complex topographic features and patterns in the datasets. As a result, the network model has a mean absolute percent error of 0.470% for testing datasets. This implies that the topographic patterns on a large scale may coincide with variations of available solar irradiation prior to the effects of weather. Thus, the integration of raster map data with solar energy prediction has emerged to systematically learn the terrain patterns in order to predict the annual amount of solar irradiation in a region of interest. This approach can aid the determination of suitable locations for the installation of solar panels.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A data-driven modeling method is presented for the prediction of solar irradiation. </LI> <LI> The regional impact of topographic features on solar energy can be modeled. </LI> <LI> An error of 0.470% was achieved for solar irradiation prediction with testing data. </LI> <LI> The topographic features show similar patterns of available solar irradiation. </LI> </UL> </P>

Characteristics of Environmental Solar Ultraviolet Irradiance

Sasaki, Masako,Oyanagi, Takehiko,Takeshita, Shu Korean Society of Photoscience 2002 Journal of Photosciences Vol.9 No.2

Direct, continuous, and accurate measurements of solar ultraviolet irradiance (290-400 nm: UVR) have been carried out since 1990, by using both band-spectral ultraviolet-B (290-320 nm: UV-B) and ultraviolet-A (320-400 nm: UV-A) radiometers at Tokai University in Hiratsuka, Japan (35$^{\circ}$N, 139$^{\circ}$E). From our observations, the following findings are provided: 1) an increasing trend in solar UV -B from Oct. 1990 to Sept. 2000; 2) a regional comparison of solar UVR in Japan; 3) the distinct characteristics of UV-B and UV-A irradiance, such as diffuse property, daily and seasonal variation; and 4) human body protection against solar UVR. An increasing 10-year trend in global solar UV - B in Hiratsuka corresponded to a decrease in the total ozone amount measured at Tsukuba (36$^{\circ}$N, 140$^{\circ}$E), giving supportive evidence for a direct link between these two parameters. Furthermore, a strong correlation was found between solar UV-B and total ozone amount from results of UVR measurements at four Tokai University monitoring stations dispersed throughout Japan. Additional results revealed different diffuse properties in global solar UV and in global solar total (300-3000 nm: Total) irradiances. For example, in the global UVR, the diffuse component was dominant: about 80 % independent of weather, with more than 60 % of global UV-B, and more than 50% of global UV-A with even a cloudless clear sky. On the other hand, the portion of the diffuse in the global total irradiance was very low, less than 10 % on a cloudless clear day. Daily and seasonal variations of UV -B and UV -A irradiances were found to be quite different, because of the marked dependence of UV -B irradiance on the atmospheric ozone amount. Moreover, UV -B irradiance showed large daily and seasonal variations: the ratio between maximum and minimum irradiances was more than 5. In contrast, the variation in UV-A was small: the ratio between maximum and minimum was less than 2. Three important facts are proposed concerning solar UVR protection of the human body: 1) the personal minimal erythema dose (MED); 2) gender based difference in MED values; and 3) proper colors for UVR protective clothing.

Advanced Forecasting Approach to Improve Uncertainty of Solar Irradiance Associated with Aerosol Direct Effects

( Dong Hyeok Kim ),( Jung Woo Yoo ),( Hwa Woon Lee ),( Soon Young Park ),( Hyun Goo Kim ) 한국환경과학회 2017 한국환경과학회지 Vol.26 No.10

Numerical Weather Prediction (NWP) models such as the Weather Research and Forecasting (WRF) model are essential for forecasting one-day-ahead solar irradiance. In order to evaluate the performance of the WRF in forecasting solar irradiance over the Korean Peninsula, we compared WRF prediction data from 2008 to 2010 corresponding to weather observation data (OBS) from the Korean Meteorological Administration (KMA). The WRF model showed poor performance at polluted regions such as Seoul and Suwon where the relative Root Mean Square Error (rRMSE) is over 30%. Predictions by the WRF model alone had a large amount of potential error because of the lack of actual aerosol radiative feedbacks. For the purpose of reducing this error induced by atmospheric particles, i.e., aerosols, the WRF model was coupled with the Community Multiscale Air Quality (CMAQ) model. The coupled system makes it possible to estimate the radiative feedbacks of aerosols on the solar irradiance. As a result, the solar irradiance estimated by the coupled system showed a strong dependence on both the aerosol spatial distributions and the associated optical properties. In the NF (No Feedback) case, which refers to the WRF-only stimulated system without aerosol feedbacks, the GHI was overestimated by 50-200 W m^-2 compared with OBS derived values at each site. In the YF (Yes Feedback) case, in contrast, which refers to the WRF-CMAQ two-way coupled system, the rRMSE was significantly improved by 3.1-3.7% at Suwon and Seoul where the Particulate Matter (PM) concentrations, specifically, those related to the PM₁₀ size fraction, were over 100 μg m^-3. Thus, the coupled system showed promise for acquiring more accurate solar irradiance forecasts.

영농형 태양광 발전 시설 하부의 일사량 분포 모의

정영준,최원,이상익,이종혁,서병훈,김동수,이지민 한국농공학회 2022 한국농공학회논문집 Vol.64 No.2

Agrivoltaic facility is the composite system that the solar panel is installed above the farmland, and it enables crop and electricity productionsimultaneously. Solar panels of the agrivoltaic facilities can block and reduce the amount of solar irradiance arriving at the farmland, but it can helpthe crop growth by preventing excessive solar irradiance. Therefore, to clarify how the agrivoltaic facilities affect the crop growth, precise solarirradiance distribution under the solar panel should be modeled. In this study, PAR (photosynthetically active radiation), radiation from 400 to 700 nm,which crops usually use to grow, was extracted from the total irradiance and its distribution model under various conditions was developed. Monthlyirradiance distributions varied because the elevation of the sun was changed over time, which made the position changed that the local maximum andminimum irradiance appear. The higher panel height did not cause any significant difference in the amount of irradiance reaching below the solar panel,but its distribution became more uniform. Furthermore, the panel angles with the most irradiance arriving below the solar panel were different by month,but its difference was up to 2%p between the irradiance with 30° angle which is usually recommended in Korea. Finally, the interval between panelswas adjusted; when the ratio of the length of the panel to the empty space was 1:2, the irradiance of 0.719 times was reached compared to whenthere was no panel, 0.579 times for 1:1 and 0.442 times for 2:1.

천리안 위성 영상 기반 태양자원지도를 활용한 다양한 정의에서의 청천지수 특성 분석

김창기,김현구,강용혁,윤창열 한국태양에너지학회 2019 한국태양에너지학회 논문집 Vol.39 No.3

Clear sky indices were estimated by various ways based on in-situ observation and satellite-derived solar irradiance. In principle, clear sky index defined by clear sky solar irradiance indicates the impacts of cloud on the incoming solar irradiance. However, clear sky index widely used in energy sciences is formulated by extraterrestrial irradiance, which implies the extinction of solar irradiance due to mainly aerosol, water vapor and clouds drops. This study examined the relative difference of clear sky indices and then major characteristics of clear sky irradiance when sky is clear are investigated. Clear sky is defined when clear sky index based on clear sky irradiance is higher than 0.9. In contrast, clear sky index defined by extraterrestrial irradiance is distributed between 0.4 and 0.8. When aerosol optical depth and air mass coefficient are relative larger, solar irradiance is lower due to enhanced extinction, which leads to the lower value of clear sky index defined by extraterrestrial irradiance.

태양광발전 시스템의 일사량에 따른 전력 패턴 분석

이경섭(Kyung-Sup Lee) 대한전기학회 2009 전기학회논문지 P Vol.58 No.4

In this thesis, output voltage, current and power of solar module were classified by irradiation from data of overall operating characteristics collected for one year in order to manage efficient photovoltaic generation system and deliver maximum power. In addition, from these data, correlations between irradiation of photovoltaic cell and amount of power given by photovoltaic cell was quantitatively examined to deduce optimization of the design and construction of photovoltaic generation system. As I-V characteristics according to a temperature range of 10~50[℃], the area of I-V characteristics were increased with an increase in temperature. Since this area corresponds to the power, output power is thought to have increased with temperature. As output power characteristics according to a temperature range of 10~50[℃], output power was increased with an increase in temperature. Since output power increases with temperature increase, the result corresponds well to the related equation on temperature and output power. As I-V characteristics according to a irradiation range of 100~900 [W/㎡], voltage and current were increased with an increase in irradiation. The result is thought of as an increase in output power with increasing irradiation. As output power characteristics according to a irradiation range of 100~900[W/㎡], output power was increased with increasing irradiation. This result corresponds well to the related equation on irradiation and output power.

서울지역 일사량 및 외기온도와 단결정 실리콘 태양광 모듈온도의 상관성에 대한 실증분석

윤다은,박형동,이상남,강용혁 한국자원공학회 2017 한국자원공학회지 Vol.54 No.2

This study analyzed photovoltaic module temperature which affects power generation of photovoltaic systems. The influence of irradiance and ambient temperature on the module temperature was confirmed using data measured in Seoul area. The module temperature increased with increasing irradiance and was similar to ambient temperature at night. Also, as a result of regression analysis, it was confirmed that the effect of irradiance on the module temperature was different depending on intervals of solar irradiance. Correlation between irradiance and module temperature was not valid in an irradiance group under 300 W/m2. The effect of irradiance on the module temperature increased between 300–800 W/m2 and decreased over 800 W/m2. This study has potential in prediction models according to intervals of irradiance. It could eventually lead to more accurate prediction of module temperature and solar power generation. 본 연구에서는 태양광 발전 시스템의 발전량에 영향을 미치는 모듈온도에 대한 실증분석을 실시하였다. 일사량, 외기온도 등 서울지역에서 측정한 기상요소와 모듈온도 자료를 이용하여 일사량과 외기온도가 모듈온도에 미치는 영향을 파악하였다. 실험 및 데이터 분석 결과, 모듈온도는 외기온도와 경향이 동일하고 외기온도를 기본 값으로가졌으며, 일사량의 영향이 더해져서 최종 모듈온도가 정의될 수 있음을 확인하였다. 또한, 모듈온도에 대한 일사량의 회귀분석 결과, 일사량 300 W/m2, 800 W/m2을 기준으로 모듈온도와 일사량의 상관성이 없는 구간, 모듈온도에 대한 일사량의 영향력이 증가하는 구간, 감소하는 구간으로 나눌 수 있었다. 이를 토대로 단일 식을 사용하는 기존 모델보다 해당 지역 자료를 이용하여 일사량 구간별 예측 모델을 사용하는 것이 더 적절함을 확인했다. 본 연구는 서울지역의 실측 자료를 이용하였기 때문에 향후 서울지역에 설치될 시스템 설치 환경을 파악할 수 있으며, 일사량 구간에 따른모듈온도 예측모델 제안 가능성을 보여주어 태양광 발전 시스템 설계 및 발전량 예측에 기여할 것으로 기대된다.

국내 지역별 일사량을 고려한 버스 탑재형 태양광 패널의 발전량 예측

최찬웅,장병춘,곽민주,진지원 한국기계기술학회 2023 한국기계기술학회지 Vol.25 No.3

Numerous studies have attempted to predict the energy output of solar-powered vehicles based on different parameters such as road conditions, driver characteristics, and weather. However, since these studies were conducted on stationary vehicles, they are limited in their accuracy when applied to driving vehicles. This study aimed to improve the accuracy of electric power prediction for a solar-powered bus by applying a technique that improves energy efficiency without affecting driving performance. A comparative analysis of power generation and solar irradiance data was conducted for the bus driven on different roads to forecast its power generation, and a high-accuracy power generation prediction equation was derived. A comparison with actual test results revealed that a power generation forecast accuracy of at least 90% was achieved, validating the equation used for forecasting. With this power generation prediction process, it is possible to forecast the amount of energy generated in advance when a solar bus is operated in a specific area.

Efficient modification of transparent graphene electrodes by electron beam irradiation for organic solar cells

Kim, S.H.,Noh, Y.J.,Kwon, S.N.,Kim, B.N.,Lee, B.C.,Yang, S.Y.,Jung, C.H.,Na, S.I. Korean Society of Industrial and Engineering Chemi 2015 Journal of industrial and engineering chemistry Vol.26 No.-

A simple, solvent-free, and efficient electron beam (EB)-irradiation based modification of graphene and its use as a transparent electrode in organic solar cells (OSCs) were described in this research. A chemical vapor deposition (CVD)-prepared graphene was irradiated by an energetic EB for various irradiation times to modify its chemical and electrical properties. The analytical results revealed that the graphene was successfully modified by EB irradiation-induced oxidation and amorphization, and thereby resulting in the increase in its sheet resistance and work function. Moreover, on the basis of the results of the OSC-performance test, the OSCs with the graphene electrode modified at the irradiation time of 5s exhibited the highest power conversion efficiency of 2.76%, which is much better than that with a non-irradiated graphene electrode. Therefore, it can be confirmed that the EB irradiation could be used in effectively tuning the graphene's properties and the resulting EB-treated graphene can be directly applicable as a transparent electrode and beneficial for high-performance organic electronics.

Efficient modification of transparent graphene electrodes by electron beam irradiation for organic solar cells

김수현,노용진,권성남,김병남,이병철,양시영,정찬희,나석인 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.26 No.-

A simple, solvent-free, and efficient electron beam (EB)-irradiation based modification of graphene and its use as a transparent electrode in organic solar cells (OSCs) were described in this research. A chemical vapor deposition (CVD)-prepared graphene was irradiated by an energetic EB for various irradiation times to modify its chemical and electrical properties. The analytical results revealed that the graphene was successfully modified by EB irradiation-induced oxidation and amorphization, and thereby resulting in the increase in its sheet resistance and work function. Moreover, on the basis of the results of the OSCperformance test, the OSCs with the graphene electrode modified at the irradiation time of 5 s exhibited the highest power conversion efficiency of 2.76%, which is much better than that with a non-irradiated graphene electrode. Therefore, it can be confirmed that the EB irradiation could be used in effectively tuning the graphene’s properties and the resulting EB-treated graphene can be directly applicable as a transparent electrode and beneficial for high-performance organic electronics