• Current Photovoltaic Research
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• v.9 no.3
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• pp.84-95
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• 2021

The power conversion efficiency of Cu₂ZnSnSe₄ (CZTSe) solar cells depends on the absorber layer thickness; however, changes in the characteristics of the cells with varying absorber layer thickness are unclear. In this study, we investigated the changes in the characteristics of CZTSe solar cells for varying absorber layer thickness. Five absorber thicknesses were employed: CZTSe1 2.78 ㎛, CZTSe2 1.01 ㎛, CZTSe3 0.55 ㎛, CZTSe4 0.29 ㎛, and CZTSe5 0.15-0.23 ㎛. The efficiency of the CZTSe solar cells decreased as the absorber thickness decreased, resulting in power conversion efficiencies of 10.45% (CZTSe1), 8.67% (CZTSe2), 7.14% (CZTSe3), 3.44% (CZTSe4), and 1.54% (CZTSe5). As the thickness of the CZTSe absorber layer decreased, the electron-hole recombination at the grain boundaries and the absorber-back-contact interface increased. This caused an increase in the current loss, owing to light loss in the long-wavelength region. In addition, as the thickness of the CZTSe absorber layer decreased, more ZnSe was produced, and the resulting defects and defect clusters led to an open-circuit voltage loss.

• Solar Energy
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• v.1 no.1
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• pp.1-11
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• 1981

The electric generation system by solar energy was built which is composed of $10m^2$ reflector, parabolic mirror and the absorbers. The absorber(I) is a single iron pipe and the absorber (II) contains seven small iron pipes. The ratio of the area of the reflectors to that of the absorber is around 99.4-440. The absorber(II) is more efficient in power than (II) by 5.6 percent. The steam power efficiency of the absorber (II) is 25 percent in this experiments and 20 percent efficiency would be expected for 80.000 Kilowatts.

• 한국신재생에너지학회:학술대회논문집
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• 2005.11a
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• pp.595-598
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• 2005

The thermal performance of glass evacuated tube solar collectors are numerically and experimentally investigated. Four different shapes of solar collectors are considered and the performances of these solar collectors are compared. Dealing with a single collector tube, the effects of not only the shapes of the absorber tube but also the incidence angle of solar irradiation (beam radiation) on thermal performance of the collector are studied. However the solar irradiation consists of the beam radiation as well as the diffuse radiation. Also, the interference of solar irradiation and heat transfer interaction between the tubes exist in an actual solar collector. These effects are considered in this study experimentally and numerically the accuracy of the numerical model is verified by the experimental results. The result shows that the thermal performance of the absorber used a plate fin and U-tube is the best.

• New & Renewable Energy
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• v.2 no.1 s.5
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• pp.56-65
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• 2006

The thermal performance of glass evacuated tube solar collectors are numerically and experimentally investigated. Four different shapes of solar collectors are considered and the performances of these solar collectors are compared. Dealing with a single collector tube, the effects of not only the shapes of the absorber tube but also the incidence angle of solar irradiation (beam irradiation) on thermal performance of the collector are studied. However, the solar irradiation consists of the beam irradiation as well as the diffuse irradiation. Also, the interference of solar irradiation and heat transfer interaction between the tubes exist in an actual solar collector, These effects are considered in this study experimentally and numerically. The accuracy of the numerical model is verified by the experimental results. The result shows that the thermal performance of the absorber used a plate fin and U-tube is the best.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.157.1-157.1
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• 2016

In this work, we experimentally investigated the solar absorption performance of Cu-based scalable nanostructured surfaces and compared their performance with the conventional TiNOX. We fabricated Cu-based nanostructured surfaces with a controlled chemical oxidation process applicable to a large area or complex geometry. We optimized the process parameters including the chemical compounds, dipping time and process temperature. We conducted both lab-scale and outdoor experiments to characterize the conversion efficiency of each absorber surfaces with single and double glazing setup. Lab-scale experiment was conducted with $50mm{\times}50mm$ absorber sample with 1-sun condition (1kW/m2) using a solar simulator (PEC-L01) with measuring the temperature at the absorber plate, cover glass, air gap and ambient. From the lab-scale experiment, we obtained ${\sim}91^{\circ}C$ and $94^{\circ}C$ for CuO and TiNOX surfaces after 1 hr of solar illumination at single glazing, respectively. To measure the absorber performance at actual operating condition, outdoor experiment was also conducted using $110mm{\times}110mm$ absorber sample. We measured the solar flux with thermopile detector (919P-040-50). From outdoor experiment, we observed ${\sim}123^{\circ}C$ and $131^{\circ}C$ for CuO and TiNOX with 0.6 kW/m2 insolation at double glazing, respectively. We showed that the suggested nanostructured CuO solar absorber has near-equivalent collection efficiency compared with the state-of-the-art TiNOX surfaces even with much simpler manufacturing process that does not require an expensive equipment.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.7
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• pp.659-668
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• 2005

The thermal performances of glass evacuated tube solar collectors are numerically investigated. Four different shapes of solar collectors are considered and the performances of these solar collectors are numerically investigated. Dealing with only collecting tube, the effects of not only the shape of the absorber tube but also the incidence angle of solar irradiation on the thermal performance of the collector are studied because the energy obtained by the absorber can be varied according to the incidence angle of solar radiation. However, the solar irradiation consists of the beam radiation as well as the diffuse radiation. Also, in actual system, the interference of solar irradiation and heat transfer interaction between the tubes should be considered. Therefore, this study considered these effects is carried out experimentally and numerically. The accuracy of the numerical model is verified by experiments. The result shows that the thermal performance of the absorber used a plate fin and U-tube is about $25\%$ better than those of the other models.

• Journal of the Korean Solar Energy Society
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• v.27 no.3
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• pp.149-154
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• 2007

It is essential to know the heat transfer characteristics at the absorber plate of Flat-plate solar collector for optimum design. For flat-plate solar collector, it is difficult to experimentally study the effect for the Reynolds number of riser considering low mass flow rate being applied into the collector with one riser tube. So, this study were performed to show the heat transfer characteristics of flat-plate solar collector with single absorber plate and riser for various Reynolds number at riser using commercial code FLUENT 6.0. The base collector size is chosen with $0.4m^2$ as 0.2m by 2m with single riser in this study, Reynolds number at riser is from 200 to 1200 including about 530 at typical flat-plate collector with 10 risers considering the mass flow rate of 0.02kg/s per collector area for the certificate test Through the simulation, the results were presented as the temperature distribution at the absorber plate for various flow rate and solar irradiance conditions, then showed the effective length scale of the absorber plate The real solar irradiation condition is assumed as the constant heat flux condition of $500w/m^2$ considering the annual average solar irradiance in Korea.

• Journal of the Korean Electrochemical Society
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• v.14 no.2
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• pp.61-70
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• 2011

Thin film solar cells with chalcopyrite $CuInSe_2/Cu(In,Ga)Se_2$ absorber materials, commonly known as "CIS/CIGS solar cells" have recently attracted significant research interest as a potential alternative energy-harvesting system for the next generation. Among the different deposition techniques available for the CIGS absorber layer, electrodeposition is an effective and low cost alternative to vacuum based deposition methods. This article reviews progress in the area of CIGS solar cells with an emphasis on electrodeposited absorber layer. Existing challenges in fabrication of stoichiometric absorber layer are highlighted.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1485-1490
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• 2003

This paper is the analysis of thermal and fluid in solar concentration absorber with various tilt angle and opening ratio of absorber entrance. The purpose of this study is to develop optimum solar concentration absorber, and the parameters for the study are the opening ratio of absorber entrance and the tilt angle. The aspect ratio of absorber was fixed at 0.64, and opening ratio was changed from 0.1 to 1.0. The finite volume method with SIMPLE computational algorithm are used and analyzed the heat transfer in absorber inside walls.

• Journal of the Korean Solar Energy Society
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• v.25 no.1
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• pp.19-25
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• 2005

All-glass evacuated tube solar collectors consist of glass evacuated tubes and absorber tubes. Solar thermal energy from the sun is transferred to the working fluid through the glass evacuated tube and the absorber tube. Several collectors which have different absorber tubes are tested to find the effects of the absorber tube shapes and the operating conditions such as the incident heat flux and the flow rate. As the results, the efficiency of the collector which has a finned tube U tube is about $2{\sim}5%$ higher than that of the others in all cases on an average. And the collector has a finned U tube has the highest efficiency at the high flow rate and the low incident heat flux. In this condition, the outlet mean temperature is low and the heat loss becomes small. Also, it is known that the fin effect is greater than the shade effect.