Chatchai Sirisamphanwong

The Study of Decrement in Insulation Resistance of PV String and its Effects on PV System Degradation

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 Standard. The 10.152 kW multi-PV cell technologies grid connected system supports the energy demand of the 10 kW Building at School of Renewable Energy Technology (SERT), Naresuan University since July 2005 till date. In general the system was found effectively working under hot and humid climatic conditions of Thailand for a long duration. However the decrement in insulation resistance (MΩ) of a-Si string, MC-Si string and HIT string have affected electrical parameter of each system. The decrements in fill factor (F.F) over the 10 years period (July 13, 2005 – January 25, 2015) of a-Si, MC-Si and HIT were-27.4%, -21.9% and-6.2% respectively.

Effect of Tilt and Azimuth Angle on the Performance of PV Rooftop System

This paper focuses on to evaluate technical performance of PV roof top system. This system totally consists of 168 polycrystalline modules in which 14 are connected in series and 12 are connected in parallel. The total capacity of the system is 50 kWp, in which each module has the rated power capacity of 305 Watt. This system is connected to three 20kW inverters and which intern is connected to grid. Tilt angle and orientation is obtained by MATLAB 7.10 and PVsyst software for each 150 change in tilt angle, the variation in solar irradiance absorbed by the PV modules, variation in energy produced by the modules and the variation in the final yield are observed. MATLAB software is also used to find the curve fitting by using surface fitting tool. The result showed that at 150 tilt and 450 azimuth angles, the maximum yield and effective energy were obtained as 4.65 h/day and 1394 kWh/kWp/year respectively.

Design and Implementation of an Interleaved Boost DC-DC Converter for PEM Fuel Cells

This paper elaborates a design and implementation of a 2-phase interleaved boost DC-DC converter as the power conditioning circuit for PEM fuel cells. The converter ripple current is analyzed so as to determine the inductance value, which would draw the fuel cell ripple current less than 4 % of its nominal value for a longer lifetime and efficient operation. Compact design is benefited from reduced inductor core volume due to paralleled connection as well as microprocessor-based control. Practical implementation is also discussed. Selection of simulation and experimental results is presented to validate the design methodology. The converter has the maximum output power of 1 kW at the output voltage of 120 V with the efficiency better than 92 %.

Investigation on Thermal Absorptivity of PCM Matrix Material for Photovoltaic Module Temperature Reduction

Photovoltaic (PV) system experience challenges from module temperature (Tmod) increasing particularly due to stagnation of thermal energy (TE) on its surface. Efforts to reduce the Tmod is widely experimented in many ways, like incorporating latent heat storage material (PCM) with PV module to reduce the Tmod through radiation and convection heat transfer. This paper focuses on selecting of an effective thermal absorption material for the fabrication of PCM matrix and optimization of the critical spacing between the PV module and PCM matrix. The thermal absorptivity of Aluminum (Al) and Copper (Cu) were analyzed with and without coated absorber at different spacing conditions. It was observed that Al tube matrix with coated absorber was absorbed 3.0 °C more than copper at 6 mm distance from module. Hence further studies on the Tmod reduction will be effective with the use of Al as PCM matrix tube.

Study of an Isolated DC-DC Converter for Fuel Cell Applications

This paper presents the analysis and design of a dual active bridge DC-DC converter for fuel cell applications. The zero voltage switching operating condition of such converter is analyzed to select an appropriate turn ratio of the high frequency transformer for a high efficiency operation. The ratio between the output voltage to the fuel cell voltage should be close to the transformer turn ratio to guarantee the zero voltage switching regimes at a light load. The prototype converter was designed to be suitable for the input voltage of 40 to 65 V and output voltage of 360 to 400 V with the transformer turn ratio of 7.33. The converter was tested with a 48 V DC power supply and with a polymer electrolyte membrane fuel cell stack. The maximum power of 700 W was delivered and the efficiency was better than 94% for the whole load range.

Statistical Load Modeling for School of Renewable Energy Technology (SERT) Smart Grid Naresuan University Phitsanalok Thailand

The high level of renewable electricity generation is resulting in transformation of conventional grid into Smart Grid. Due to variable electricity generation the load demand has become critical and challenging issue in electricity market. In this study, the end-use load modeling based on probability distribution has been carried out in School of Renewable Energy Technology (SERT) Naresuan University Phitsanalok Thailand. For the data of electricity usage in office at SERT the most suitable model i.e., Weibull distribution have been emulated. The shape and scale parameters have been estimated along with Kolmogorov-Smirnov goodness of fit test.

Insulation Resistance and Leakage Current in PV Modules and Strings with Different Grounding Configurations

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 leakage currents in passing through laminate permeation and back sheet from cell to ground frame. The PID occure in PV systems when connected in series using DC voltages of high orders. This research shows comparisons of both PV systems, with negative grounding and floating grounding with a system voltage about 800 Vdc. Investigations of insulation resistance (MΩ) in PV strings and modules after two years operation has been done. It was found that the decrement in average insulation resistance (MΩ) of PV string using negative grounding, floating grounding was 14.5 MΩ, 11.0 MΩ and average leakage current per string was 68.9 µA, 90.9 µA respectively. Moreover, the wet leakage current per module showed the decrement in average insulation resistance (MΩ.m2) was 174 MΩ.m2, 133 MΩ.m2 and average leakage current per module was 5.75 µA, 7.51 µA respectively.

Techno-Economic Performance Evaluation and Enhancement for a PV – Diesel Hybrid System

In this research paper, an illustration for system size optimization for a stand-alone PV – diesel hybrid system is obtained. The requirement is to obtain an optimal size that can meet energy demand at an optimized cost for a given lifetime period of the project, this will be achieved using HOMER software to further improve the system parameters like performance ratio, renewable energy fraction, MATLAB will be used. This research study will be done basing on a system currently installed at the School of Renewable Energy, Naresuan University (SERT), this system has a capacity of 120 kW, and it is a hybrid system with PV array, Diesel generator and battery storage system. The cost parameters that will be addressed are; - Net present cost (NPC), Cost of Energy (COE), Capital cost (CC). The initial size of the hybrid system is PV-120kW, Diesel generator -100kW and battery storage of 200kWh after modelling and simulation with HOMER software using special models to show the predicted performance of the final outcome, the optimal size created has a PV size of 100kW, diesel generator with a size of 100kW and battery storage of 100kWh and compared to the initial system COE od 1.01

A DSP-based interleaved boost DC–DC converter for fuel cell applications

/kWh, the optimal size has a COE of 0.934

Comparison the Economic Analysis of the Battery between Lithium-ion and Lead-acid in PV Stand-alone Application☆

/kWh.