Kobsak Sriprapha

Kobsak Sriprapha
National Electronics and Computer Technology Center | NECTEC · Solar Energy Technology Laboratory (STL)

Doctor of Engineering

About

67
Publications
32,602
Reads
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794
Citations
Additional affiliations
January 2013 - November 2016
National Electronics and Computer Technology Center
Position
  • Senior Researcher
March 1999 - present
National Electronics and Computer Technology Center
Position
  • Senior Researcher

Publications

Publications (67)
Article
As photovoltaic (PV) power generation systems become more widespread instability of the electric power grids with PV connection is becoming an issue. For appropriate management of the grids, probability prediction of solar irradiance is proposed. Lagged Average Forecast (LAF) method is used for ensemble forecasting. The 72-hour ahead forecasting of...
Article
Many Photovoltaic (PV) systems are connected to electric power grids, and the grids get risk of instability due to the fluctuations of PV output. Numerical Weather Prediction (NWP) models are used for forecasting the solar irradiance and proper grid management. NWPs usually have many physical parameterization options, and appropriate schemes of the...
Article
Prediction of photovoltaic (PV) system generations is a powerful tool for managing the electric grids with multiple PV systems for reducing the instability of their electricity supply. For the prediction, weather and solar irradiance forecasting using a numerical meteorological model are performed in this study. The target country is Thailand which...
Article
Nowadays, lubricants play an important role in several automotive industries around the world because they reduce friction and wear on engines moving parts such as piston ring, cylinder liner and valve control systems of compression ignition engines. The aim of this research was to investigate the impact of bio-oil (palm oil) on metallic wear. The...
Article
Napier grass found to be greatest potential for gaseous bioenergy production. The biohydrogen and biomethane productions from untreated Napier grass in single and two-stage continuous bioreactors was evaluated using anaerobic digestion technology. The bioreactors were fed Napier grass with organic loading rate (OLR) of 0.5, 1.0 and 2.0 kg VS/m³-d,...
Article
The effect of soot contamination on the tribological performance of engine oil was investigated. Carbon black is introduced to simplify diesel engine soot contamination. Besides, the tribological performance issue is verified by a four-ball tribometer. The steel ball worn surfaces were studied by Scanning Electron Microscope (SEM), Optical Microsco...
Article
We investigated the effect of the flow rate of CO2 on the optical and structural properties of i-a-Si1−xOx:H films deposited using 27-MHz very-high-frequency plasma-enhanced chemical vapor deposition. Experimental results show that with an increasing CO2 flow rate, the optical bandgap of the film was increased due to the increase of the oxygen conc...
Article
Full-text available
This research presents a method to improve data accuracy for the more efficient data management of the studied applications. The data accuracy was improved using the preciseness function learning model (PFL model). It contains a database in which the amount of data is more or less dependent on all of the possible behavior of the studied application...
Article
Indium tin oxide (ITO) films were used as transparent conductive oxide (TCO) layers in crystalline silicon heterojunction (c-Si-HJ) solar cells. An ITO film was deposited by radio frequency (RF) magnetron sputtering with the oxygen-argon (O2–Ar) gas mixture. The increasing of the O2/Ar ratio in ITO film deposition resulted in the improvement of tra...
Article
Full-text available
The power output forecasting of the photovoltaic (PV) system is essential before deciding to install a photovoltaic system in Nakhon Ratchasima, Thailand, due to the uneven power production and unstable data. This research simulates the power output forecasting of PV systems by using adaptive neuro-fuzzy inference systems (ANFIS), comparing accurac...
Article
Full-text available
Perovskite solar cells have been attracted as new representatives for the third-generation photovoltaic devices. Simple strategies for high efficiency with the long-term stability of solar cells are the challenges for commercial solar cell technology. Another challenge of the development toward industrial scale in perovskite solar cells is the prod...
Article
Full-text available
In this study, a micro-encapsulated phase change material (PCM) was composed of sugarcane wax-Al2O3composite as the core material and gelatin-gum Arabic as the polymer shell materials prepared by complex coacervation. The thermal behavior of solar panels integrated with this encapsulated PCM (EPCM) was investigated. The heat storage-dissipation per...
Chapter
This work focused on the development of DC smart plug for efficient data monitoring and transmission. The transmitted data were collected from smart plug sensors and user commands, and sent via wireless transmission to the online database. The results revealed that the smart plug could control and provide high speed wireless data transmission with...
Chapter
This work is an on-going research to develop a smart farm system with environmental analysis for terrace vegetable farming with web application. The terrace farm is separated into 3 levels of moisture settings according to the type of vegetables that require low, medium or high moisture content. The environmental sensors monitor the moisture in the...
Conference Paper
div class="section abstract"> The soot contamination in used engine oils of diesel engine vehicles was about 1% by weight. The soot and metal wear particle sizes might be in the range of 0-1 µm and 1-25 µm, respectively. The characteristics of soot affecting on metal wear was investigated. Soot particle contamination in diesel engine oil was simula...
Article
Spectroscopic ellipsometry (SE) was used to characterize the effect of the CO2/SiH4 ratios on the p-type hydrogenated microcrystalline silicon oxide (p-μc-SiOx:H) thin films. The p-μc-SiOx:H thin films were fabricated by very high frequency plasma-enhanced chemical vapor deposition (VHF-PECVD) method on the soda-lime glass substrates. The CO2/SiH4...
Article
Intrinsic amorphous silicon oxide (i-a-SiO:H) films were used as passivation layers in crystalline silicon heterojunction (c-Si-HJ) solar cells. The effective lifetime (τeff) and photovoltaic (PV) parameters were improved by controlling the CO2/SiH4 ratio in the i-a-SiO:H rear passivation layer. The enhancement of the open circuit voltage (Voc) and...
Article
Hydrogenated amorphous silicon oxide (a-Si1−xOx:H) film was used as a buffer layer at the p-layer (μc-Si1−xOx:H)/i-layer (a-Si1−xGex:H) interface for a narrow band gap hydrogenated amorphous silicon germanium (a-Si1−xGex:H) single-junction solar cell. The a-Si1−xOx:H film was deposited by plasma enhanced chemical vapor deposition (PECVD) at 40 MHz...
Article
After 4 years of operation at Thailand Science Park, degradation analysis of 73 photovoltaic (PV) modules of four different PV technologies; multi c-Si, hetero-junction Si, micromorph and CIGS, has been carried out. The degradation rate (DR) of individual modules and array performance are presented. It was found that some micromorph (thin film Si 1...
Article
Full-text available
A novel technique has been developed for PV array internal resistance measurement while keeping the plant in operation in contrary to flash test or basic equation (Eb) for which the modules need to be disconnected from the system. We present an equation developed for the array’s internal resistance measurement for PV technologies namely Amorphous S...
Article
Full-text available
Thailand is located in the tropical zone dominated by monsoons for more than six months in a year. These climatic conditions illustrate elevated relative humidity and temperature that contributes to Potential Induced Degradation (PID). Humidity has been reported to be potential cause of degradation in the systems with high voltages. Moisture helps...
Article
Full-text available
This paper presents the investigated variations in insulation resistances of amorphous silicon (a-Si), multi crystalline silicon (MC-Si) and hybrid solar cell (HIT). The insulation resistance of PV string of each system was measured and used to represent leakage current in photovoltaic system and the analysis was done in accordance with IEC 61215 S...
Article
Full-text available
This paper proposes a new concept to improve accuracy of PV forecasting model. The model was implemented by MATLAB/Simulink software using solar irradiance and module temperature as measurement parameters for calculation. The model was developed by single-diode equivalent circuits (5-p model) for simulated PV module power output and compared with o...
Article
Full-text available
Performance loss rates of five different photovoltaic (PV) technologies operating under Thailand's climate have been derived from the first 3-year data. Although ambient temperature throughout the year in the tropics is relatively constant, we found remarkable seasonal variations in performance loss of the PV modules. The performance loss rate...
Article
Full-text available
Hydrogenated amorphous silicon germanium (a-SiGe:H) films prepared by very high frequency plasma-enhanced chemical vapor deposition (VHF-PECVD) using a mixture of SiH4, H2, and GeH4 were investigated for their use as the bottom cell of amorphous silicon/amorphous silicon germanium (a-Si:H/a-SiGe:H) tandem solar cell structures. Narrow optical band...
Article
Full-text available
This paper presents the dynamic characteristic of a tandem silicon/amorphous silicon (a-Si:H/a-Si:H) photovoltaic (PV) module measured in the nonstationary regime. The current-voltage (I-V) characteristics of the PV module are generally measured by using a pulsed solar simulator. Distortions of the I-V curves can often be observed when measurements...
Article
Full-text available
Intrinsic hydrogenated amorphous silicon oxide (i-a-SiO:H) films were used as front and rear buffer layers in crystalline silicon heterojunction (c-Si-HJ) solar cells. The surface passivity and effective lifetime of these i-a-SiO:H films on an n-type silicon wafer were improved by increasing the CO2/SiH4 ratios in the films. Using i-a-SiO:H as the...
Article
Full-text available
This paper reports the preparation of wide gap p-type hydrogenated microcrystalline silicon oxide (p-c-SiO:H) films using a 40 MHz very high frequency plasma enhanced chemical vapor deposition technique. The reported work focused on the effects of the CO2/SiH4 ratio on the properties of p-c-SiO:H films and the effectiveness of the films as an emitt...
Article
Full-text available
The effects of temperature on performance of a grid-connected inverter, and also on a photovoltaic (PV) system installed in Thailand have been investigated. It was found that the maximum efficiency of the inverter showed 2.5% drop when ambient temperature was above 37°C. The inverter performed efficiently in November and December, the months of hig...
Article
Full-text available
In heterojunction solar cells, a-Si:H/c-Si heterointerface is of significant importance, since the heterointerface characteristics directly affect junction properties and thus solar cell efficiency. In this study, we have performed time resolved microwave conductivity (TRMC) measurements on n-type c-Si wafers passivated on both sides with intrinsic...
Article
Full-text available
We have prepared Ag back electrode by screen printing technique and developed MOCVD ZnO/screen printed Ag back reflector for flexible thin film silicon solar cell application. A discontinuity and poor contact interface between the MOCVD ZnO and screen printed Ag layers caused poor open circuit voltage (Voc) and low fill factor (FF); however, an ins...
Article
Hydrogenated amorphous silicon oxide (a-SiO: H)/hydrogenated amorphous silicon (a-Si: H) double-junction solar cells with a high open-circuit voltage (V-oc) and a low temperature coefficient (TC) were developed using a wide bandgap a-SiO: H film as the intrinsic (i) layer of the top cell. It was found that with an increasing carbon dioxide (CO2)/si...
Article
Full-text available
Zinc oxide (ZnO) films with a very high haze ratio and low resistivity were developed on soda–lime glass substrate by using reactive ion etching (RIE) treatment with carbon tetrafluoride (CF4) to modify the substrate surface morphology before the deposition of ZnO films. We found that the surface morphology of the ZnO films deposited by metal organ...
Article
Full-text available
We report on the development and application of n-type hydrogenated microcrystalline silicon oxide films (n μc-SiO:H) in hydrogenated amorphous silicon oxide/hydrogenated microcrystalline silicon (a-SiO:H/μc-Si:H) micromorph solar cells. The n μc-SiO:H films with high optical bandgap and low refractive index could be obtained when a ratio of carbon...
Article
Full-text available
Optimization of p-type hydrogenated microcrystalline silicon oxide thin films (p-c-:H) by very high frequency plasma enhanced chemical vapor deposition 40 MHz method for use as a p-layer of a-Si:H solar cells was performed. The properties of p-c-:H films were characterized by conductivity, Raman scattering spectroscopy, and spectroscopic ellipsomet...
Article
Full-text available
Normally, the main generators of microgrid system use controllable energy resources such as fossil fuel, biomass, biogas, hydro, etc for uncomplicated control. However, it is very challenging to control the microgrid system that uses uncontrollable energy resources such as solar and wind for main generators of microgrid system because they have man...
Article
We have developed zinc oxide (ZnO) film and CO2 plasma treatment for the use as an intermediate layer between top and bottom cell in order to improve performance of micromorph silicon solar cells. The CO2 plasma treatment was performed by very high frequency plasma-enhanced chemical vapor deposition (VHF PECVD) technique, and the ZnO interface laye...
Article
We have developed p type hydrogenated silicon oxide (p type SiO:H) films which fabricated near the phase between amorphous and microcrystalline silicon oxide (a-SiO:H and μc-SiO:H) transition region in order to improve the open circuit voltage (Voc) and short circuit current density (Jsc), of thin film silicon solar cells. A mixed gas of diborane (...
Article
Wide gap, high quality hydrogenated intrinsic amorphous silicon oxide (i-a-SiO:H) films have been prepared by very high frequency plasma-enhanced chemical vapor deposition (60 MHz VHF-PECVD) technique for using as an absorber layer for the single junction amorphous silicon solar cells. In this study, we mainly investigated the effect of plasma powe...
Article
We have prepared ZnO films by MOCVD technique and applied them as a back reflector in flexible thin film silicon solar cells. The gas mixture of diethylzinc and water was used as reactant gas while diborane was employed as a doping gas. We found that the MOCVD ZnO films had a tetrapodlike morphology and their properties strongly depended on substra...
Article
We have developed thin film silicon double-junction solar cells by using micromorph structure. Wide bandgap hydrogenated amorphous silicon oxide (a-SiO:H) film was used as an absorber layer of top cell in order to obtain solar cells with high open circuit voltage (Voc), which are attractive for the use in high temperature environment. All p, i and...
Article
Full-text available
We have prepared n-type hydrogenated microcrystalline silicon oxide films (n μc-SiO:H) and investigated their structural, electrical and optical properties. Raman spectra shows that, amorphous phase of the n μc-SiO:H films tends to increase when the CO2/SiH4 ratio increases from 0 to 0.28 resulting in a reduction of the crystalline volume fraction...
Article
Full-text available
The temperature dependence of Si-based thin-film single junction solar cells on the phase of the intrinsic absorber is investigated in order to find the optimal absorber at high operating temperatures. For comparison, hydrogenated amorphous, protocrystalline, and microcrystalline silicon solar cells are fabricated by plasma-enhanced chemical vapor...
Article
In dye sensitized solar cell structure, the transparent electrodes of tin oxide doped fluorine (SnO(2):F) was coated by titanium dioxide (TiO(2)) and platinum (Pt) for cathode and anode electrodes, respectively. In order to achieve high efficiency solar cell, both electrodes are required to have proper crystal structure size and morphology. These c...
Conference Paper
Full-text available
This study aimed to focus on the outdoor performance ratio (PR) and the relationship between PR, module temperature and irradiance for (a-Si) and polycrystalline silicon (poly-Si) located in Thailand. The result of this study revealed that the PR of a-Si increased during the summer and reached the highest value in the rainy season. For a 3-year per...
Article
Full-text available
We investigated the properties of hydrogenated amorphous silicon oxide (a-Si1-xOx:H) deposited near the phase transition between amorphous and microcrystalline structures. a-Si1-xOx:H films were prepared by plasma-enhanced chemical vapor deposition using a gas mixture of silane, hydrogen, and carbon dioxide. The film structure was changed from amor...
Article
Full-text available
In this work, we investigated the temperature dependence of wide bandgap hydrogenated amorphous silicon (a-Si:H)-based, hydrogenated amorphous silicon oxide (a-SiO:H)-based single-junction and hydrogenated protocrystalline silicon/hydrogenated microcrystalline silicon (pc-Si:H/μc-Si:H) double-junction solar cells in order to develop solar cells whi...
Conference Paper
Full-text available
Hydrogenated amorphous silicon oxide (a-SiO:H) films were prepared by very high frequency plasma enhanced chemical vapor deposition (VHF-PECVD) using mixture of SiH 4 , H 2 and CO 2 source gas. The optical bandgap (Eopt) in the range between 1.90 and 2.02 eV was obtained by the variation of CO 2 flow rate and H 2 dilution. With increasing of H 2 di...
Article
The light-soaked and annealing behaviors for silicon (Si)-based thin-film single-junction solar cells fabricated near the phase boundary using a very-high-frequency plasma-enhanced chemical vapor deposition (VHF PECVD) technique are investigated. The hydrogen dilution ratio is changed in order to achieve wide band gap hydrogenated amorphous Si (a-S...
Article
Full-text available
We have investigated the temperature dependence of hydrogenated protocrystalline silicon (pc-Si:H)/hydrogenated microcrystalline silicon (μc-Si:H) double-junction solar cells. A boron-doped zinc oxide (ZnO:B) film is employed as an intermediate layer between the pc-Si:H top cell and the μc-Si:H bottom cell. The fabricated solar cells exhibit good s...
Article
Full-text available
The temperature dependence of silicon (Si)-based thin-film single-junction solar cells, whose intrinsic absorbers were fabricated on the transition phase between hydrogenated amorphous silicon (a-Si:H) to hydrogenated microcrystalline silicon (μc-Si:H), was investigated. By varying the hydrogen dilution ratio, wide-band-gap protocrystalline silicon...
Article
Full-text available
The temperature dependence of silicon (Si)-based thin film single junction solar cells whose intrinsic absorbers were fabricated near the phase boundary of hydrogenated amorphous silicon (a-Si:H) to hydrogenated microcrystalline silicon (muc-Si:H) was investigated. By varying the hydrogen dilution ratio, wide bandgap protocrytalline silicon (pc-Si:...
Article
Full-text available
The authors develop a hydrogenated protocrystalline silicon (pc-Si:H)/hydrogenated microcrystalline silicon (μc-Si:H) double-junction solar cell structure employing a boron-doped zinc oxide (ZnO:B) intermediate layer. Highly stable intrinsic pc-Si:H and μc-Si:H absorbers are prepared by a 60 MHz very-high-frequency plasma-enhanced chemical vapor de...
Article
Full-text available
A numerical study using Analysis of Microelectronic and Photonic Structures (AMPS) device simulator has been carried out to examine how the operating temperature and spectral irradiance affect the behavior of a hydrogenated amorphous silicon/hydrogenated microcrystalline silicon (a-Si:H/muc-Si:H) tandem cell. We have proposed a new tunnel-recombina...

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