• Current Photovoltaic Research
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• v.6 no.1
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• pp.27-30
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• 2018

The dependency of the electrical characteristics of silicon solar-cells on the depth of damaged layer induced by wire-sawing process was investigated. To compare cell efficiency with residual sawing damage, silicon solar-cells were fabricated by using as-sawn wafers having different depth of saw damage without any damaged etching process. The damaged layer induced by wire-sawing process in silicon bulk intensely influenced the value of fill factor on solar cells, degrading fill factor to 57.20%. In addition, the photovoltaic characteristics of solar cells applying texturing process shows that although the initial depth of saw-damage induced by wire-sawing process was different, the value of short-circuit current, fill-factor, and power-conversion-efficiency have an almost same, showing ~17.4% of cell efficiency. It indicated that the degradation of solar-cell efficiency induced by wire-sawing process could be prevented by eliminating all damaged layer through sufficient pyramid-surface texturing process.

• Proceedings of the KIEE Conference
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• 1987.11a
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• pp.200-202
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• 1987

Sintered CdS films on glass substrate with low electrical resistivity and high optical transmittance have been prepared by coating and sintering method. All-polycrystalline CdS/CdTe solar cells with different microstructure and properties of CdTe layer were fabricated by coating a number of CdTe slurries, which consisted of Cd and Te powders, an appropriate amount of propylene glycol and 2 or 7.5 w/o $CdC1_2$, on the sintered CdS films and by sintering the glass-CdS-(Cd+Te) composites at various temperature. To explore the dependence of the solar efficiency on the preparation conditions of the CdTe layer, Cd powder with an average particle size of $0.3{\mu}m$ or $5{\mu}m$ was prepared. The use of Cd with finer particles forms more dense or uniform microstructure of the nuclear of CdTe during the heating. Therefore the use of Cd with finer particles improves the efficiency of the sintered CdS/CdTe solar cell by improving the microstructure of sintered CdTe layer. But the difference of solar efficiency by varing a particle size of Cd is decreased with increasing amount of $CdC1_2$ in the (Cd+Te) layer. All-polycrystalline CdS/CdTe solar cells with an efficiency of 10.2% under solar irradiation have been fabricated using a Cd with finer particles.

• 한국태양에너지학회:학술대회논문집
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• 2011.04a
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• pp.293-298
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• 2011

The most widely used method to form an electrode in industrial solar cells are screen printing. Screen printing is characterized by a relatively simple and well-known production sequence with high throughput rates. However the method is difficult to implement a fine line width of high-efficiency solar cells can not be made. The open circuit voltage(Voc) and the short circuit current density(Jsc) and fill factor(FF) need to be further improved to increase the efficiency of silicon solar cells. In this study, gravure offset printing method using the multicrystalline-silicon solar cells were fabricated. Gravure off-set printing method which can print the fine line width of finger electrode can have the ability reduce the shaded area and increase the Jsc. Moreover it can make a high aspect ratio thereby series resistance is reduced and FF is increased. Approximately $50{\mu}m$ line width with $35{\mu}m$ height was achieved. The efficiency of gravure off set was 0.7% higher compare to that of scree printing method.

• Magazine of the Korean Society of Agricultural Engineers
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• v.32 no.E
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• pp.74-79
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• 1990

Important factors in evaluating solar collcetor efficiency are solar radiation, temperature and flow rate of the working fluid. The effects of these factors on the energy and the exergy gained by water, the working fluid, from the collector were analyzed. The results indicated that the collector efficiency and the energy and the exergy gained by the water from the collcetor increased with the increase of solar radiation. According to the exergy analysis, as the water temperature at the inlet of the collector increased, the exergy gained by the water increased while the energy gained by the water decreased. The water temperature at the outlet of the collector could be calculated with a mean error of 2.8%, and the energy and the exergy could be calculated theoretically with mean errors of 16.8% and 19.1%, respcetively.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.4
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• pp.331-338
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• 2015

Solar air heaters (SAHs) are simple in design and widely used for solar energy collection devices, and a packed bed is one of typical solar energy storage systems of thermal energy captured by SAHs. This paper presents mathematical modeling and simulation on the thermal performance of various packed bed energy storage systems. A MATLAB program is used to estimate the thermal efficiency of packed bed SAH. Among the various packed bed energy storage systems considered, the wire mesh screen packed bed SAH shows the best thermal efficiency over the entire range of design conditions. The maximum of thermal efficiency of packed bed SAH with wire mesh screen matrices has been found to be 0.794 for Re=2000 - 20000 and ${\Delta}T/I=0.002-0.02$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.223-224
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• 2008

Important element are low cost, high-efficiency crystalline silicon solar cells. in this paper, Will be able to contribute in low cost, high-efficiency silicon solar cells, Applies oxide/nitride passivation, produced screen-printed solar cells. and the Measures efficiency, and evaluated a justice quality oxide/nitride passivation screen-printed solar cells.

• Journal of the Optical Society of Korea
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• v.19 no.2
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• pp.199-205
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• 2015

We investigated the effects of the thickness and doping concentration in p- and n-type poly-Si layers on the performance of a solar cell based on a carbon fiber in order to improve the energy conversion efficiency of the cell. The short-circuit current density and open-circuit voltage of the carbon fiber-based solar cell were significantly influenced by the thickness and doping concentration in the p- and n-type poly-Si layers. The solar cell efficiency was successfully enhanced to ~10.5%.

• Journal of the Semiconductor & Display Technology
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• v.18 no.2
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• pp.32-37
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• 2019

In this paper, we have designed a solar photovoltaic system to attach solar photovoltaic modules to each module and develop the best efficiency in each module. The efficiency of the designed solar panel optimizer was more than 99.27% and MPPT efficiency of 99.66%. In addition, the monitoring of power generation and abnormal operation phenomenon in each optimum period and tracking for failure location of specific photovoltaic module have improved the utilization rate of photovoltaic power generation. Wired and wireless communication methods has been proposed to monitor the power generation and operation status of the solar panel optimizer. For this purpose, the RS485 communication was used for wire communication and Zigbee communication was used for wireless communication to monitor the status of each module in real time. It is shown that communication redundancy can be achieved through the proposed method, and the possibility of commercialization is suggested.

• Journal of the Korean Solar Energy Society
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• v.37 no.3
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• pp.33-45
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• 2017

Crystalline silicon photovoltaic module certification began in 2007. "Renewable Energy Equipment Certification Scheme" was implemented until July 28, 2015. Then, the scheme was changed to "KS Certification Scheme" since July 29, 2015. A total of 2,331 models have been certified by 2016. The proportion of multi crystalline modules in certified products is higher than that of mono crystalline modules, and Korean modules account for 78% of the total certification modules. Chinese solar cells account for the highest percentage of 40% of the total modules and 62.4% of modules certified in 2016 use Chinese solar cells. With the development of technology, module power is continuously increasing, and efficiency is also rising. The average efficiency of mono crystalline module is 0.74% higher than the average of multi crystalline module. As a result of comparing domestic module with Chinese module, the highest efficiency of mono crystalline module and multi crystalline module and the average efficiency of mono crystalline module are higher than those of Chinese module, but the average efficiency of multi crystalline module is similar to that of Chinese module.

• Journal of Bio-Environment Control
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• v.5 no.1
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• pp.57-64
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• 1996

To use effectively the solar energy in greenhouse heating, a high performance solar collector should be developed. And then the size of the solar collector and thermal storage tank should be determined through the calculation of heating load. The solar collector must be set in the optimum tilt angle and direction to take daily solar radiation maximally, and the flow rate of heat transfer fluid through the solar collector should be kept in the optimum range. In this research, the performance tests of a capillary tube solar collector were performed to determine the optimum water flow rate and the results summarized as follows. 1. The regressive equations for efficiency estimations of the capillary tube solar collector in the open loop were modeled in the water flow rate of 700-l,000 $\ell$/hr. 2. The optimum water flow rate of the solar collector was estimated by the second order polynomial regression and the maximum efficiency was 80% at the water flow rate of 850 $\ell$/hr. 3. The solar thermal storage system consisted of a capillary tube solar collector and a water storage tank was tested at the water flow rate of 850 $\ell$/hr in the closed loop, and obtained the solar thermal storage efficiency of 55.2%. 4. As the capillary tube solar collector engaged in this experiment was made of non-corrosive polyolefin tubes, its weight was as light as 1/30 of the flat plate solar collector made of copper tubes. Therefore it was considered to be suitable for the greenhouse heating system.