셀 표면의 충돌제트를 이용한 태양광발전 시스템 효율향상에 관한 연구

유상필(Yoo Sang-Phil),진주석(Jin Joo-Seok),김혁균(Kim Hyuk-Kyun),김이현(Kim Yi-Hyun),정성대(Jeong Seong-Dae),서용석(Seo Yong-Seo),정남조(Jeong Nam-Jo) 한국태양에너지학회 2009 한국태양에너지학회 학술대회논문집 Vol.- No.-

This study is focused on the improving effectiveness of a photovoltaic system. The characteristic of crystalline silicon solar cells, that 0.5% reduction in generating power is occurred by increasing temperature 1℃ of module. Typically, average solar generating power is higher spring and fall than summer. Degradation phenomena shall shorten the life of the module when the temperature of modules is 70℃. Decreasing temperature 40degree of the module and increasing the solar power 20% was presented using the water impinging jet method on the surface of photovoltaic cells. It is shown that Impinging jet have an effected on heat and deliver effective substance from the area in which the injection is effective.

Enhanced Switchable Ferroelectric Photovoltaic Effects in Hexagonal Ferrite Thin Films via Strain Engineering

Han, Hyeon,Kim, Donghoon,Chu, Kanghyun,Park, Jucheol,Nam, Sang Yeol,Heo, Seungyang,Yang, Chan-Ho,Jang, Hyun Myung American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.2

<P>Ferroelectric photovoltaics (FPVs) are being extensively investigated by virtue of switchable photovoltaic responses and anomalously high photovoltages of similar to 10(4)V. However, FPVs suffer from extremely low photocurrents due to their wide band gaps (E-g). Here, we present a promising FPV based on hexagonal YbFeO3 (h-YbFO) thin-film heterostructure by exploiting its narrow E-g. More importantly, we demonstrate enhanced FPV effects by suitably exploiting the substrate-induced film strain in these h-YbFO-based photovoltaics. A compressive-strained h-YbFO/Pt/MgO heterojunction device shows similar to 3 times enhanced photovoltaic efficiency than that of a tensile-strained h-YbFO/Pt/Al2O3 device. We have shown that the enhanced photovoltaic efficiency mainly stems from the enhanced photon absorption over a wide range of the photon energy, coupled with the enhanced polarization under a compressive strain. Density functional theory studies indicate that the compressive strain reduces E-g substantially and enhances the strength of d-d transitions. This study will set a new standard for determining substrates toward thin-film photovoltaics and optoelectronic devices.</P>

지형 효과를 고려한 지표면 태양광 분포

지준범,조일성,이규태,최영진 한국지구과학회 2011 한국지구과학회지 Vol.32 No.2

지형 효과가 포함된 태양복사 모델(GWNU)을 이용한 한반도의 태양광 자원지도를 개발하였다. 태양복사 모델의입력 자료는 위성 관측 자료(MODIS, OMI, MTSAT-1R)와 수치 모델(RDAPS) 자료를 사용하였으며 특히 고해상도 지형 자료를 이용하여 지형 효과에 따른 한반도의 지표면 태양광 변화를 계산하였다. 계산 결과를 월 및 연 누적하여 분석하였을 때 여름철은 태양 고도각이 높아 지형 효과에 영향이 10% 이하로 적은 반면 겨울철은 20% 이상의 큰 차이가 나타났다. 또한 4 km 해상도의 지표면 태양광의 경우보다 1 km 해상도의 경우 지형 효과 포함에 따른 태양광 차이가 약 2배 정도 크게 나타났다. 즉 지표면에 도달하는 태양광을 정확히 모델링하기 위해서는 입력 자료뿐만 아니라 정확하고 고해상도의 지형 자료가 필연적이며 지형효과는 더욱 뚜렷이 나타나 실제와 유사할 것이다. A photovoltaic energy map that included a topography effect on the Korean peninsula was developed using the Gangneung-Wonju National University (GWNU) solar radiation model. The satellites data (MODIS, OMI and MTSAT-1R)and output data from the Regional Data Assimilation Prediction System (RDAPS) model by the Korea Meteorological Administration (KMA) were used as input data for the GWNU model. Photovoltaic energy distributions were calculated by applying high resolution Digital Elevation Model (DEM) to the topography effect. The distributions of monthly accumulated solar energy indicated that differences caused by the topography effect are more important in winter than in summer because of the dependency on the solar altitude angle. The topography effect on photovoltaic energy is two times larger with 1 km resolution than with 4 km resolution. Therefore, an accurate calculation of the solar energy on the surface requires high-resolution topological data as well as high quality input data.

A crucial factor affecting the power conversion efficiency of oxide/metal/oxide-based organic photovoltaics: Optical cavity versus transmittance

Lee, Byeong Ryong,Park, Gi Eun,Kim, Yong Woon,Choi, Dong Hoon,Kim, Tae Geun Elsevier 2019 APPLIED ENERGY Vol.235 No.-

<P><B>Abstract</B></P> <P>Considerable effort has been directed at improving the power conversion efficiency of organic photovoltaics, using oxide/metal/oxide multilayers as transparent electrodes, because of their numerous advantages including lower sheet resistance, higher transmittance, and higher flexibility in comparison to typical indium tin oxides. However, to date, most organic photovoltaics based on oxide/metal/oxide electrodes exhibit a lower conversion efficiency than indium tin oxide-based organic photovoltaics, without any clarification. In this investigation, we identify crucial factors that influence the power conversion efficiency of oxide/metal/oxide-based organic photovoltaics to fully exploit the potential of these devices, based on the correlation between the optical cavity and the transmittance. For this purpose, we fabricate five sets ofinverted organic photovoltaics using poly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-<I>b</I>:4,5-<I>b</I>′]dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-<I>b</I>]thiophenediyl}) and [6,6]-Phenyl C<SUB>71</SUB> butyric acid methyl ester-based active layers and ZnO/Ag/ZnO electrodes with top ZnO layers of varying thicknesses, with reference organic photovoltaics using indium tin oxides, on both rigid and flexible substrates. The highest power conversion efficiency of 8.71% and 7.53% is obtained from single-junction organic photovoltaics with 40/9/8-nm-thick ZnO/Ag/ZnO electrodes on each substrate, due to strong micro-cavity effects between the top and bottom Ag layers, despite the relatively low transmittance of the electrode. This result is supported by the relation between the electric-field intensity and the transmittance curves of the ZnO/Ag/ZnO/solution-based ZnO/active bulk optical stacks based on simulation results. Furthermore, flexible organic photovoltaics with the ZnO/Ag/ZnO electrodes demonstrate much better performance in mechanical bending tests in comparison to the performance of standard indium tin oxide-based organic photovoltaics, and the previously reported oxide/metal/oxide-based organic photovoltaics.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Structure for organic photovoltaics with ZnO/Ag/ZnO electrodes is optimized. </LI> <LI> Crucial factor dictating power conversion efficiency is identified in these devices. </LI> <LI> High power conversion efficiency (8.71%) is achieved from organic photovoltaics. </LI> <LI> Excellent mechanical flexibility is also observed. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>We display a crucial factor that dictates the power conversion efficiency (PCE) of OMO-based OPVs by investigating the effect of photon fields in the active region and the transmittance of the electrode on the PCE of ZnO/Ag/ZnO-based OPVs with top ZnO layers of varying thicknesses. One of the optimized OPVs exhibit record-high PCE and mechanical flexibility in these devices.</P> <P>[DISPLAY OMISSION]</P>

단독주택용 태양광발전설비의 유지관리에 관한 연구

김재엽 한국교통대학교 2015 한국교통대학교 논문집 Vol.50 No.-

Many photovoltaic equipments had been supplied owing to the government subsidy. But, the maintenance of PV equipment was not considered carefully. The subject was 202 households: 84% of the households required the maintenance. This study investigated not only maintenance methods of photovoltaic equipment for detached houses but also effects of the methods. The maintenance methods were: Maintenance companies provided users with maintenance services to be paid. And, maintenance companies provided not only Korea Energy Management Corporation but also local governments with maintenance information to be paid according to the maintenance. Photovoltaic equipment was likely to increase generation owing to maintenance method. And, job opportunity could be made to produce social effects.

냉각 시스템으로 Peltier 장치를 사용하여 태양 광 패널의 성능 분석

이드아함드파지 ( Ahmed Fawzy Eid ),홍성구 ( Hong Seong-gu ) 한국농공학회 2019 한국농공학회 학술대회초록집 Vol.2019 No.-

One of the main challenges for solar photovoltaic system is temperature rising of solar module, which causes to decrease maximum power voltage (Vmp) of panel. Furthermore, leads to decrease in electrical efficiency, maximum power (Pmax) of solar panel and will cause cells degradation and above lowering of life span expectancy of photovoltaic panels systems. To manage this issue, one of the important methods to improve the solar panel efficiency and keep it at a sufficient level is cooling. There are a lot of methods which are used to cool solar modules such as floating cooling system (FCC), photovoltaic/thermal (PVT) cooled by forced water circulation, solar panel with water immersion cooling technique and thermoelectric device as cooling systems called also Peltier effect device. In this study, two solar panels with different cooling devices were compared with a reference panel (model 3) with respect to its efficiency and performance. A new design of photovoltaic/thermoelectric cooler (PV-TEC) as a cooling system was attached with two fans and two heat sink as one unit, it fixed on the backside of the solar module to cool it from the back (model 2). Another method was a water film (model 1) to improve the electrical module efficiency. A 70 Watts small pump created a water film on the front side of the solar panel to remove the heat from the front. The first results of this study showed the temperatures were 35.5℃, 49 ℃ and 57 ℃ for model 1, model 2 and model 3 respectively. The maximum power voltages were 21.36V, 20.69V and 20.05V respectively. Short circuit currents were 5.31A, 5.36A and 5.37A respectively. The ideal output power from modules were 114W, 111W and 107.5W respectively with an improvement in electricity efficiency were 6% and 3.5% for model 1 and model 2 respectively .the cooling system by water film achieved a proper impact on electricity efficiency otherwise the capacity of the thermoelectric cooling unit was not enough to remove the heat from the back sheet of the solar module because of low thermal conductivity of Taddler layer.

전력계통 고장시 계통연계형 태양광발전시스템의 영향분석

박성훈,이용식,정성원,김재현 한국태양에너지학회 2019 한국태양에너지학회 논문집 Vol.39 No.4

Among the main functions of the grid-connected photovoltaic (PV) system, the anti-islanding operation function is a very important problem. Recently, due to the improvement in power generation efficiency and the maintenance advantages in PV system, the use of string inverter has increased so that the possibility of islanding operation has been raised. Generally, when a power system faults, the PV inverter must be disconnected from power system within 10 cycles by the anti-islanding operation function. However, in the real-time of power system, the output power of the PV system within 10cycles is effected. In this paper, we analyzed the effect of grid-connected PV system on power quality in a short time within 10 cycles on fault case of power system using the Matlab Simulink program.

Carrier-Tunneling-Induced Photovoltaic Effect of InAs/GaAs Quantum-Dot Solar Cells

Seunghyun Lee,Jong Su Kim,Sang Jun Lee 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.69 No.4

This study reports the observation of the carrier-tunneling-induced photovoltaic (PV) effect in an InAs/GaAs quantum-dot solar cell (QDSC). The illuminated current-voltage (J-V) characteristics and the applied-bias-dependent electroreflectance (ER) were measured at 12 K by using an excitation laser with a wavelength of 975 nm (1.27 eV), which excites only the quantum-dot (QD) states below the GaAs band gap. The J-V results showed a peculiar current curve in the reverse bias region caused by carrier tunneling. The ER results showed that the junction electric field (F) decreased with increasing intensity of the excitation laser (Iex) at different applied-bias-voltages (Va) due to the tunneling-induced PV effect. The PV effect was enhanced by improved tunneling with increasing reverse bias voltage. We also evaluated the tunneling carrier density (pv) as a function of Va in the QDSC.

A Density Functional Theory Study of Side Chains Effects on the Intermolecular Interactions and Electronic Structures of Small Molecular Acceptors for Organic Photovoltaics

고은지,김동욱 대한화학회 2016 Bulletin of the Korean Chemical Society Vol.37 No.8

Diketopyrolopyrole-thiophene-phenyl (DPPT-Ph)-based small acceptor molecules for organic photovoltaics application were investigated at density functional theory (DFT) level using ωB97X-D functional and 6-31G(d) basis sets: Acceptor molecules include DPPT-Ph and its cyanide analogs, o-, m-, and p-DPPT-PhCN molecules with either methyl or 2-ethylhexyl groups attached on DPP unit. With methyl side chains, acceptor molecules form π-stacked dimers, i.e., syn- and anti-cofacial configurations. Strong π–π interactions between backbone of acceptor molecules in such dimers, however, turned out not to alter absorption spectra dramatically with respect to those of single molecule due to the negligible intensity of peaks pointing to the lowest-lying excited states. On the other hand, the disruption of π–π interactions induced by the presence of side chains, albeit alleviates peak-splitting, notably intensifies such peaks at the cost of intensity reduction of the most prominent neighboring peak. Our results place significant emphasis on the importance of the manipulation of side chain to improve the device performance of organic photovoltaics.

Tailoring of the plasmonic and waveguide effect in bulk-heterojunction photovoltaic devices with ordered, nanopatterned structures

Wang, D.H.,Kyaw, A.K.K.,Du, Q.G.,Choi, D.G.,Park, J.H. Elsevier Science 2014 Organic Electronics Vol.15 No.11

Various nano-patterned bulk-heterojunction (BHJ) films with different diameters and pitches were fabricated by a stamping method to tailor the plasmonic effect. The nanopatterned BHJ active layers exhibit regular-ordered embossing structures, which were confirmed by the surface morphological analysis with SEM and AFM. The simulation results confirm that devices with nanopatterned BHJ film with a diameter/pitch of 265/400nm exhibit a strong improvement in E-field distribution intensity due to the combination of the plasmonic and waveguide modes compared to devices without a nanopattern, with 150/400nm, or with 265/800nm, which led to increased J<SUB>SC</SUB> and cell efficiency in J-V curves under solar light illumination. The optimized plasmonic effect plays an important role in the light harvesting of BHJ devices.