• Journal of Ecology and Environment
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• v.35 no.4
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• pp.343-349
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• 2012

The use of growth medium is often recommended milkweed seedlings to grow and develop after emergence, and it is affected by growth medium and local habitat conditions. The effects of growth medium and partial shade on early growth of milkweed under drought stress (Calotropis procera L.) were studied in a field experiment. A split-split plot experimental design with three replications was carried out in the nursery. The main treatment plot was divided into two levels of shade; (no shading and partial shading). Sub treatment plot1 included growth medium at four levels (G1 = clay [suitable for milkweed growth], G2 = clay + sand, G3 = clay + perlite, G4 = clay + perlite + sand) and sub treatment plot2 included drought (irrigation intervals) at six levels (D1 = 2 [control], D2 = 4, D3 = 6, D4 = 8, D5 = 10, and D6 = 12 days per for three month). The results showed that drought stress significantly decreased emergence percentage, shoot length, shoot dry weight (SDW1), root dry weight (RDW), seedling dry weight (SDW2) and vigor index (VI). The use of growth medium increased all seedling characteristics. The G3 (clay + perlite) growth medium showed the highest performance, especially in terms of emergence percentage and seedling dry weight. Partial shade improved shoot length, shoot dry weight, and vigor index. Our results showed that the best treatment for high-vigor milkweed seedlings under drought stress was G3 (clay + perlite) growth medium and partial shade.

• Journal of the Korean Solar Energy Society
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• v.29 no.2
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• pp.8-13
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• 2009

In this paper, two configurations of PV array are analyzed and tested under shading condition, where two configurations are series-parallel and total-crass-tied configuration. Each photovoltaic module is emulated by two 5 inch po1y-crystalline cells in series and an array is constructed by connecting 24 of the modules to compare a generated maximum power of the two configurations. Pspice and Sun simulator. PASAN IIIb, are used for simulation and experiment to test the array under various partial shading conditions. Test results show the total-cross-tied configuration generates 7.63% higher maximum power than the series-parallel configuration, and it is well matched to the analysis and simulations of the two configurations.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.2
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• pp.216-223
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• 2018

Since solar cells have non-linear voltage-current output characteristics, Photovoltaic systems require the Maximum Power Point Tracking(MPPT) function. For this reason, a large number of MPPT techniques have been studied. However, the conventional MPPT techniques may fail to track the maximum power point when partial shading occurs in the solar cell array due to its characteristics. Therefore, it is necessary to research the MPPT technique that can follow the maximum power point in the partial shadow condition. In this paper, the characteristics of solar cell arrays in partial shadowing are analyzed and the MPPT technique which can follow the maximum power point in partial shadow condition has been proposed. To validate the proposed MPPT method, simulation and experimentation results are provided.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.1
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• pp.38-45
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• 2021

The photovoltaic module has the characteristic of changing its output characteristics depending on the amount of radiation and temperature, where the arrays that connect them in series and parallel also have the same characteristics. These characteristics require the MPPT technique to find the maximum power point. Existing P&O and IncCond cannot find the global maximum power point (GMPP) for partial shading. Moreover, in the case of Improved-GMPPT and Enhanced Search-Skip-Judge-GMPPT, GMPP due to partial shading can be found, but the variation in the open voltage during temperature fluctuations will affect the operation of the Skip and will not be able to perform accurate MPPT operation. In this study, we analyzed the correlation between voltage, current, and power under solar module and array conditions. We also proposed a technique to find the maximum power point even for temperature fluctuations using not only the amount of radiation but also the temperature coefficient. The proposed control technique was verified through simulations and experiments by constructing a 2.5 kW single-phase solar power generation system.

• Korean Journal of Medicinal Crop Science
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• v.10 no.5
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• pp.409-414
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• 2002

This study was carried out in order to investigate the main traits related to photosynthesis by multiple regression analysis. The photosynthetic rate showed more significant increase in shaded leaves of plant than in non-shaded leaves of plant after shading treatment for 44 days. Negative correlation was found between net photosynthetic rate and SLA(specific leaf area). However, the values obtained from the linear equation were different and were highly significance. From the above results, net photosynthetic rate of shading treatment is higher than that of control in the same SLA. We also found that there were correlation between stomatal conductance and SPAD as well as net photosynthetic rate and stomatal conductance. By the multiple regression analysis, SPAD value, SLA, stomatal conductance and leaf water potential showed a higher correlation coefficient of $r=0.848^{**}$. From the results, out of 4 factors(SPAD value, SLA, stomatal conductance, leaf water potential) stomatal conductance was main factor in the view points of partial regressing.

• Journal of Navigation and Port Research
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• v.42 no.3
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• pp.167-176
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• 2018

A solar power generation system on single point moored offshore plant has independent power system In order to satisfy the maritime environment and account for the number of sunless days, it is important to supply stable electric power to the systems. For these reasons, solar panels are installed in multiple directions. However, a partial shading effect occurs because the amount of light incident on each panel is different. The generated power by the solar generation system installed on land is affected by the latitude, then it is installed at an angle of 30 to $45^{\circ}$. in the case of Korea. In the case of a solar power generation system installed in a mooring type of marine plant, there is a possibility that the maximum power point is outside of the controllable range due to the partial shading effect. Therefore, a power generation loss occurs. By reducing the light amount difference between both panels, the maximum power point can exist in a range where the MPPT algorithm can track the power. The purpose is so the power generation efficiency can be further increased. In this paper, simulation results show that the highest power generation efficiency is obtained at an installation angle of $20^{\circ}$.

• Korean Journal of Agricultural and Forest Meteorology
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• v.23 no.2
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• pp.100-107
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• 2021

An agrivoltaic system (AVS) is a system of innovation that comprises productions of photovoltaic power and agricultural crops on the same area. However, the decline in crop yield will be fatally occurred because the pigments of crop absorbs less light energy under AVS. In addtion, the photosynthetic capacity of crop grown under the partial shading of AVS is not well reported. In this study, the electron transport rate (ETR) and non-photochemical fluorescence quenching (NPQ) of soybean and rice under the AVS in Boseong and Naju was investigated using chlorophyll fluorescence measurement. The ETR value of soybean and rice under AVS were not significantly differed by location. It represents that the photophosphorylation rate of the crops is not critically different. It means that the decreases in total photosynthesis under AVS were mostly affected by the amount of light absorbed by leaves. Under AVS the photosynthesis of crops will be lower than field crops grown in open fields. This is because the crops under AVS observed higher NPQ, which means that the available energy cannot distribute to photophosphorylation reaction.

• Journal of the Korean Solar Energy Society
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• v.37 no.4
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• pp.1-11
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• 2017

Most PV modules are fabricated by 6 cell-strings with solar cells connected in series. Moreover, bypass diodes are generally installed every 2 cell-strings to prevent PV modules from a damage induced by current mismatch or partial shading. But, in the case of special purpose PV module, like as BIPV (Building Integrated Photovoltaic), the number of cell-strings per module varies according to its size. Differ from a module employing even cell-strings, the configuration of bypass diode should be optimized in the PV module with odd strings because of oppositely facing electrodes. Hence, in this study, electrical characteristics of special purposed PV module with odd string was empirically and theoretically studied depending on arrangement of bypass diode. Here, we assumed that PV module has 3 strings and the number of bypass diodes in the system varies from 2 to 6. In case of 2 bypass diodes, shading on a center string increases short circuit current of the module, because of a parallel circuit induced by 2 bypass diodes connected to center string. Also, the loss is larger, as the shading area in the center string is enlarged. Thus, maximum power of the PV module with 2 bypass diode decreases by up to 59 (%) when shading area varies from 50 to 90 (%). On the other hand, In case of 3 and 6 bypass diodes, the maximum power reduction was within about 3 (W), even the shading area changes from 50 to 90 (%). As a result, It is an alternative to arrange the bypass diode by each string or one bypass diode in the PV module in order to completely bypass current in case of shading, when PV module with odd string are fabricated.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1390-1391
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• 2011

태양광 발전 시스템에서의 최대 전력점 추적(MPPT, Maximum Power Point Tracking)제어를 실험을 하기 위해 부분선형 다이오드 모델을 이용한 태블로 해석을 통해 태양광 발전 시스템의 태양전지 모듈의 특성을 시뮬레이션 하였다. 태양전지 모듈의 V-I 특성과 태양전지 패널을 직렬-병렬 어레이로 연결 시, 부분 그늘 문제(Partial Shading Problem)의 지역 최대 점(global peak)을 시뮬레이션을 통해 확인하였다.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.2
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• pp.94-102
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• 2020

Considering that the output voltage and current of a single PV panel are limited in PV power generation, a PV array should be constructed by connecting several PV panels in series and parallel to meet the required voltage/power levels for power generation capacity. When a PV array is partially shaded, the maximum power generation depends on the configuration of a PV array and the presence or absence of blocking diodes. This study considers six PV array configurations and the presence or absence of blocking diodes. An optimum connection structure was proposed to maximize power generation in a partial shadow condition. Results were verified through simulation and an experiment.