• Applied Chemistry for Engineering
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• v.30 no.4
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• pp.504-508
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• 2019

The feasibility of replacing the tope cell of pn GaInP homojunction with our GaInP/AlGaInP heterojunction structure in III-V semiconductor multijunction photovoltaic (MJPV) cells having the highest current conversion efficiency was investigated. The performance of photovoltaic (PV) cells grown on $2^{\circ}$ and $10^{\circ}$ off-oriented GaAs substrates were compared to each other. The PV cells on the $10^{\circ}$ off-cut substrate showed higher short-circuit current density ($J_{sc}$) and conversion efficiency values than that of using the $2^{\circ}$ one. For $2{\times}2mm^2$ area PV cell on $10^{\circ}$ off substrate, the $J_{sc}$ of $9.21mA/cm^2$ and the open-circuit voltage of 1.38 V were measured under 1 sun illumination. For $5{\times}5mm^2$ cell on $10^{\circ}$ off substrate, the conversion efficiency was decreased from 6.03% (1 sun) to 5.28% (20 sun) due to a decrease in fiill factor (FF).

• New & Renewable Energy
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• v.2 no.2 s.6
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• pp.16-22
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• 2006

This paper present the performance evaluation of PV systems installed at Tibet area of China in order to identity the key factors that determines system operation at a severe climate conditions and promote the cooperation of PV technology between Korea and China. The installed systems consist of 100kW on-grid connected PV systems, BOS(balance of systems), data acquisition and transmission equipments. The Korea side supplied the solar cell, BOS like as inverter, control box and monitoring system. And the Chinese side assembled solar module, constructed site and built control house. It has been shown that the average radiation per monthly from Tibet is 1.5 times larger than that from Mokpo. Also, radiation time from Tibet is 2hour higher than that from Korea.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.47-48
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• 2011

PV(Photovoltaic) cell의 출력 전력은 일사량이나 온도와 같은 외부환경의 영향을 받아 변화하게 되므로 PV cell은 전압과 전력의 출력에 있어 비선형적이다. 이와 같은 비선형적 관계로 인해 MPPT(Maximum Power Point Tracking)를 수행하는 것이 PV 시스템에서는 매우 중요하다. 본 논문에서는 PV의 전력-전압 출력 특성에서 MPP를 기준으로 양쪽 경사면의 기울기와 Section의 차이를 이용한 새로운 추종법을 제안하였다. P-V 특성 곡선에서 왼쪽 측면에 비해 오른쪽 측면이 큰 기울기를 갖는 동시에 좁은 Section을 가지므로 제안하는 알고리즘은 이러한 특성을 활용한다. 또한 EMTP를 이용하여 제안된 기법의 성능과 동작을 검증하였다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.11
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• pp.30-39
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• 2012

The characteristics of I-V and P-V of solar cell nonlinearly changes according to irradiation, temperature and load. Therefore, to use efficiently PV system, operating point must be always operating at maximum power point. Also, PV system is semiconductor, so it generates loss by temperature. But because of conventional MPPT methods are not considering temperature, it has problem which decrease efficiency. This paper proposes temperature measurement based optimal voltage(TMOV) MPPT algorithm using temperature measurement based optimal voltage. It analyzes characteristics of solar cell according to irradiation and temperature and conventional MPPT methods. The TMOV control algorithm proposed in this paper is compared and analyzed conventional MPPT methods. The validity of this paper proves using this result.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.125-129
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• 2006

This paper presents the isolation and performance evaluation of PV systems installed at Tibet area of China in order to identity the key factors that determines system operation at a severe climate conditions and promote the cooperation of PV technology between Korea and China. The installed systems consist of 100kW on-grid connected PV systems, BOS(balance of systems), data acquisition and transmission equipments. The Korea side supplied the solar cell, BOS like as inverter, control box and monitoring system. And the Chinese side assembled solar module by using Koreans solar cells, constructed site and built control house.

• KIEAE Journal
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• v.15 no.1
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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.

• Journal of Advanced Marine Engineering and Technology
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• v.27 no.6
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• pp.696-703
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• 2003

A photovoltaic power generation system is an infinite and clean energy system. Recently. because of the realization of high efficiency and low cost PV modules, the studies on the PV system have extensively increased. In this paper. we present an online scheme for parameter estimation of solar cell, based on the model adjustment technique and a real-coded genetic algorithm(RCGA). The ideal diode model and the diode model with series and shunt resistors are used to estimate their parameters, Simulation works using field data in the form of a V-I characteristic curve are carried out to demonstrate the effectiveness of the proposed method.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.6
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• pp.105-113
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• 2013

In this paper a micro solar energy harvesting system with MPPT(Maximum Power Point Tracking) control using a miniature PV(photovoltaic) cell of which the output is less than 0.5V is proposed. The MPPT control is implemented using linear relationship between the open-circuit voltage of a PV cell and its MPP(Maximum Power Point) voltage such that a pilot PV cell can track the MPP of the main PV cell in real time. The proposed circuit is designed in 0.18um CMOS process. The designed chip area is $900um{\times}1370um$ including a load charge pump and pads. Measured results show that the designed system can track the MPP voltage changes with variations of light intensity. The designed circuit with MPPT control delivers MPP voltages to load even though the load is heavy such that it can supply more power when the MPPT control is applied. The proposed circuit does not require any precharged battery resulting in more suitability for miniaturized self-powered systems compared to the existing works.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.134.2-134.2
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• 2014

Photonic crystal solar cells have the potential for addressing the disparate length scales in polymer photovoltaic materials, thereby confronting the major challenge in solar cell technology: efficiency. One must achieve simultaneously an efficient absorption of photons with effective carrier extraction. Unfortunately the two processes have opposing requirements. Efficient absorption of light calls for thicker PV active layers whereas carrier transport always benefits from thinner ones, and this dichotomy is at the heart of an efficiency/cost conundrum that has kept solar energy expensive relative to fossil fuels. This dichotomy persists over the entire solar spectrum but increasingly so near a semiconductor's band edge where absorption is weak. We report a 2-D, photonic crystal morphology that enhances the efficiency of organic photovoltaic cells relative to conventional planar cells. The morphology is developed by patterning an organic photoactive bulk heterojunction blend of Poly(3-(2-methyl-2-hexylcarboxylate) thiophene-co-thiophene) and PCBM via PRINT, a nano-embossing method that lends itself to large area fabrication of nanostructures. The photonic crystal cell morphology increases photocurrents generally, and particularly through the excitation of resonant modes near the band edge of the organic PV material. The device performance of the photonic crystal cell showed a nearly doubled increase in efficiency relative to conventional planar cell designs. Photonic crystals can also enhance performance of other optoelectronic devices including organic laser.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.12
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• pp.2212-2217
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• 2010

Previous studies have been focused on the voltage of Bypass diode and Isc(Short Circuit Current) of the influenced solar cell. The Bypass diode starts working when it gets the reverse applied voltage. Previous studies have only concentrated on Isc of the influenced solar cell and Imp of PV module to explain the bypassing performance. PV module is usually working together with inverter having MPPT(Maximum Power Point Tracking) function for best performance. bypassing point is regulated by MPPT function of inverter. In this paper, simulation results of Bypass diode in PV module have been analyzed to represent the relationship of the bypassing point with the composition of PV module. From the results, the more cells are connected with each string, the earlier bypassing performance happens under the fixed number of strings. As diode groups increase or irradiation decreases, the bypassing performance starts fast.