• 한국신재생에너지학회:학술대회논문집
• /
• 2010.11a
• /
• pp.137.1-137.1
• /
• 2010

For Indonesia, sustainable energy supply is an important factor to preserve the stable economic growth. One important strategy is development of renewable energy, which has not been fully exploited yet. The paper examines the potency of renewable energy in Indonesia. Currently, biomass composes 23% of total primary energy supply, while geothermal and hydropower has a combined share of 3%. But according to the overall potency of renewable energy, hydropower is found to have the highest available resource of 76 GW, followed by biomass and geothermal by 49.81 GW and 28.53 GW, respectively. Although the solar radiation is only at modest level ($4.80kWh/m^2/day$), the tropical all year sunlight can boost the competitiveness of solar photovoltaic and thermal application. As for wind energy, the average speed of 3-6 m/s requires the development of low speed wind turbine. The examination of electricity and petroleum product prices through international comparison for non-OECD countries shows fifth lowest price level for both of petroleum products and electricity for industrial use. As for household electricity price, Indonesia is placed the second among all the countries compared. The energy subsidy and price structure are examined in detail because it could be a source of hindrance to renewable energy promotion. The examination of renewable energy potency in this study could provide insights about recent development of renewable energy in Indonesia. As an outcome of policy examination, the price comparison analysis suggests Indonesia to reduce or even remove the energy subsidies in the long run. These findings can be utilized to formulate effective policies for renewable energy promotion.

• Journal of Korean Association for Spatial Structures
• /
• v.11 no.1
• /
• pp.105-112
• /
• 2011

Fundamental Electric vehicle charge system is urgently needed for commercialization of electric vehicles. Car parking building is equipped with PV system for providing electricity to charge electric vehicles, because it must be charged at least for 30 minutes. In parking lots abroad, electric car charging stations are installed to charge electric cars by the electricity gained from PV systems which are also installed. Also, charge infrastructure construction plans and electric car charging facility support standards are being set and proposed, but there are no cases like abroad of electric car charging stations using PV systems and only electric car charging stations using ordinary electricity are being proposed. Therefore, this paper prepares establishment of domestic electric car charging networks. By researching inside outside solar parking lots and cases of abroad PV system electric car charging stations, and by analysis and comparative analysis of structural systems, structural material, and etc., many cantilever structure and small-size types were installed in PV system electric car charging stations.

• Journal of the Korean Solar Energy Society
• /
• v.31 no.4
• /
• pp.80-86
• /
• 2011

Investigation of the effective soil thermal conductivity(k) is the first step in designing the ground loop heat exchanger(borehole) of a geothermal heat pump system. Another important factor is the borehole thermal resistance($R_b$). Thermal response tests offer a good method to determine the ground thermal properties for the total heat transport in the ground. This is done by supplying a constant heat power into a borehole heat exchanger. There are two methods to supply a constant heat power. One is to employ the electricity provided by Korea Electric Power Corporation(KEPCO). The other is to use electricity generated by a generator. In this study, the power supply regulation was found to reduce when the electricity generated by the generator was used. This is because the generator evaluated with the power supply characteristically reduces the power supply regulation between an overload and a complex using. But it sometimes occurs a power supply regulation in In-situ thermal response test. In this case getting of k,$R_b$ requires delay times and restored normal state. However, the effect of the delay times and restored normal state on the soil thermal conductivity and borehole thermal resistance is very small. Therefore it is possible to use a generally accepted delay times and restored normal state in the analysis. In this work, it is also shown that an acceptable range of ${\Delta}k$, ${\Delta}R_b$ for normal state and regulation state might be approximately 0.01-0.16W/m k, and -0.004-0.007m K/W, respectively. Thus, restored normal state of power supply regulation is valuable to recommend.

• KEPCO Journal on Electric Power and Energy
• /
• v.8 no.2
• /
• pp.69-72
• /
• 2022

This paper actually investigates the load on major large-scale buildings in the downtown area, examines the economic feasibility of installing PV and ESS in a microgrid target building, and evaluates whether an electric vehicle capable of V2G through two buildings is effective as an economical analysis program (HOMER) was analyzed using. It is economical to install a mixture of ESS rather than using the whole PV, and it is shown that if there is an electric vehicle using the V2G function of EV, there is an economic effect to replace the PV. So that Incentives and policies are needed to replace a large area of PV and utilize the existing parking lot to lead EV as a resource of the microgrid. Currently, P2X technology that stores power as ESS or converts it to other energy to control when surplus renewable energy occurs in large-capacity solar power plants and wind farms, etc. This is being applied, and efforts are being made to maintain the stability of the system through the management of surplus power, such as replacing thermal energy through a heat pump. Due to the increase in electric vehicles, which were recognized only as a means of transportation, technologies for using electric vehicles are developing. Accordingly, existing gas stations do not only supply traditional chemical fuels, but electricity, and super stations that also produce electricity have appeared. Super Station is a new concept power plant that can produce and store electricity using solar power, ESS, V2G, and P2G. To take advantage of this, research on an urban microgrid that forms an independent system by tying a large building and several buildings together and supplies power through a super station around the microgrid is in full swing.

• Environmental and Resource Economics Review
• /
• v.30 no.3
• /
• pp.435-469
• /
• 2021

The main purpose of this study is to identify the determinants of electricity import and export in 26 European Union countries using the Spatial durbin model(SDM). In particular, we would like to mainly explain it based on the amount of power generated by each energy source. Not just the usual way of constructing a weighting matrix based on contiguity, we adopt a weighting method based on the proportion of trade among countries with connected electricity systems. Moreover, the electricity systems of European countries are directly and indirectly connected, which is reflected in the weighting matrix. According to the results, nuclear power has a positive effect on exports and a negative effect on imports, and an increase in wind and solar power has a positive effect on both exports and imports by increasing power system instability. While Korea is unable to trade electricity due to geopolitical conditions, the results of this study are expected to provide implications for energy policies.

• Advances in Energy Research
• /
• v.5 no.2
• /
• pp.179-205
• /
• 2017

This research presents an in-depth analysis of location planning of the solar-hydrogen power plants for electricity production in different cities situated in Kerman province of Iran. Ten cities were analyzed in order to select the most suitable location for the construction of a solar-hydrogen power plant utilizing photovoltaic panels. Data envelopment analysis (DEA) methodology was applied to prioritize cities for installing the solar-hydrogen power plant so that one candidate location was selected for each city. Different criteria including population, distance to main road, flood risk, wind speed, sunshine hours, air temperature, humidity, horizontal solar irradiation, dust, and land costare used for the analysis. From the analysis, it is found that among the candidates' cities, the site of Lalezar is ranked as the first priority for the solar-hydrogen system development. A measure of validity is obtained when results of the DEA method are compared with the results of the technique for ordering preference by similarity to ideal solution (TOPSIS). Applying TOPSIS model, it was found that city of Lalezar ranked first, and Rafsanjan gained last priority for installing the solar-hydrogen power plants. Cities of Baft, Sirjan, Kerman, Shahrbabak, Kahnouj, Shahdad, Bam, and Jiroft ranked second to ninth, respectively. The validity of the DEA model is compared with the results of TOPSIS and it is demonstrated that the two methods produced similar results. The solar-hydrogen power plant is considered for installation in the city of Lalezar. It is demonstrated that installation of the proposed solar-hydrogen system in Lalezar can lead to yearly yield of 129 ton-H2 which covers 4.3% of total annual energy demands of the city.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.64 no.2
• /
• pp.1-13
• /
• 2022

Agrivoltaic facility is the composite system that the solar panel is installed above the farmland, and it enables crop and electricity production simultaneously. Solar panels of the agrivoltaic facilities can block and reduce the amount of solar irradiance arriving at the farmland, but it can help the crop growth by preventing excessive solar irradiance. Therefore, to clarify how the agrivoltaic facilities affect the crop growth, precise solar irradiance distribution under the solar panel should be modeled. In this study, PAR (photosynthetically active radiation), radiation from 400 to 700 nm, which crops usually use to grow, was extracted from the total irradiance and its distribution model under various conditions was developed. Monthly irradiance distributions varied because the elevation of the sun was changed over time, which made the position changed that the local maximum and minimum irradiance appear. The higher panel height did not cause any significant difference in the amount of irradiance reaching below the solar panel, but its distribution became more uniform. Furthermore, the panel angles with the most irradiance arriving below the solar panel were different by month, but its difference was up to 2%p between the irradiance with 30° angle which is usually recommended in Korea. Finally, the interval between panels was adjusted; when the ratio of the length of the panel to the empty space was 1:2, the irradiance of 0.719 times was reached compared to when there was no panel, 0.579 times for 1:1 and 0.442 times for 2:1.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.15 no.5
• /
• pp.577-584
• /
• 2015

A photovoltaic (PV) system generates electricity by installing a solar energy array; therefore, the photovoltaic system can be easily exposed to external factors, which include environmental factors such as temperature, humidity, and radiation. These factors-as well as shading, in particular-lead to power degradation. When there is an output loss in the solar cell of a PV module package, the output loss is partly controlled by the bypass diode. As solar cells become highly efficient, the characteristics of series resistance and parallel resistance improve, and the characteristics of reverse voltage change. A bypass diode is connected in parallel to the string that is connected in series to the PV module. Ideally, the bypass diode operates when the voltage is -0.6[V] around. This study examines the bypass diode operating time for different types of crystalline solar cells. It compares the reverse voltage characteristics between the single solar cell and polycrystalline solar cell. Special modules were produced for the experiment. The shading rate of the solar cell in the specially made solar energy module was raised by 5% each time to confirm that the bypass diode was operating. The operation of the bypass diode is affected not only by the reverse voltage but also by the forward bias. This tendency was verified as the number of strings increased.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.36 no.5
• /
• pp.442-453
• /
• 2023

Tandem or multijunction solar cells (MJSCs) can convert sunlight into electricity with higher efficiency (η) than single junction solar cells (SJSCs) by dividing the solar irradiance over sub-cells having distinct bandgaps. The efficiencies of various common SJSC materials are close to the edge of their theoretical efficiency and hence there is a tremendous growing interest in utilizing the tandem/multijunction technique. Recently, III-V materials integration on a silicon substrate has been broadly investigated in the development of III-V on Si tandem solar cells. Numerous growth techniques such as heteroepitaxial growth, wafer bonding, and mechanical stacking are crucial for better understanding of high-quality III-V epitaxial layers on Si. As the choice of growth method and substrate selection can significantly impact the quality and performance of the resulting tandem cell and the terminal configuration exhibit a vital role in the overall proficiency. Parallel and Series-connected configurations have been studied, each with its advantage and disadvantages depending on the application and cell configuration. The optimization of both growth mechanisms and terminal configurations is necessary to further improve efficiency and lessen the cost of III-V on Si tandem solar cells. In this review article, we present an overview of the growth mechanisms and terminal configurations with the areas of research that are crucial for the commercialization of III-V on Si tandem solar cells.

• Current Photovoltaic Research
• /
• v.11 no.4
• /
• pp.134-143
• /
• 2023

Efforts are being made to respond to global warming. Interest in and demand for the private sector-led RE100 campaign is also increasing. Self-built solar power generation, one of the implementation tools for RE100, is not expanding. However, it can be an economical means of implementation in the long run. In this study, we intend to analyze the impact on the optimal ratio of self-solar power generation using HOMER simulation. OPR defines the optimal solar power generation ratio and looks into what changes there are in the optimal solar power ratio when self-power consumption increases and external power purchase price changes. As a result, the optimal rate of self-solar power generation has a low impact even if self-power consumption increases. As the external power unit price increases, the optimal ratio increases, and at a power unit price of 100 KRW/kWh, OPR is 24%; at 200 KRW/kWh OPR is 31%; and at 300 KRW/kWh OPR is 34%. This shows that the electricity price replaced during the life cycle has a high impact on the economic feasibility of solar power generation. However, when the external power unit price reached a certain level, the increase in OPR decreased. This shows that it is difficult for domestic companies to achieve RE100 based on the economic feasibility of solar energy alone. Therefore, efforts are needed to supply renewable energy in the public sector.