UTAR
COST EFFECTIVE SOLAR POWER PLANT USING INDIGENOUS TECHNOLOGY OF NON-IMAGING FOCUSING ON HELIOSTAT & CONCENTRATOR PHOTOVOLTAIC
| Researcher : |
Dr Chong Kok Keong
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Designation :
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Head of Programme
(Bachelor of Science (Hons) Physics)
Assistant Professor
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Faculty:
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Faculty of Engineering and Science
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Department:
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Department of Electrical and Electronic
Engineering
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Email Address:
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Background information
There is increasing interest in concentrator photovoltaic (CPV) power generation as an alternative or to complement the existing power generation systems that consume fossil fuels. Nevertheless, the main obstacle preventing large scale implementation of solar electricity production is the high price of the photovoltaic modules caused by high material cost of the photovoltaic cell and low conversion efficiency. Since the photovoltaic modules are the expensive component in a solar system, the use of concentrators can increase the irradiation on the cells and thus utilize the cells more efficiently.
To facilitate the possibility of harnessing more solar energy at the receiver, the first prototype of Non-Imaging Planar Concentrator (NIPC) has been designed and constructed (Fig. 1). This concentrator is formed by numerous flat mirrors acting as an optical aperture to collect and to focus the incident sunlight into the target along the optical axis (Fig. 2), to achieve a good uniformity of the solar irradiation with a reasonably high concentration ratio on the target.
Fig. 1: The prototype of Non-Imaging Planar Concentrator
Fig. 2: The Principle and Concept of Non-Imaging Planar Concentrator (NIPC)
Following our research and in the novel planar concentrator (Chong et al., 2009), the next step is to research on the technology of densely packed CPV module. The encouragement from the advances in state-of-the-art multi-junction solar cells, now achieving over 40% conversion efficiency which is about double the efficiency of conventional flat plate photovoltaic (PV) module solar cells ranging from 10% to 17%, have propelled to the selection of triple-junction solar cells. The small-area multi-junction solar cells are of about 1 cm2 (Fig 4) and are becoming of interest to be applied in high concentration terrestrial applications (Sherif et al., 2002; Kinsey et al.,2006; Kurokawa et al., 2007). In our research, high efficiency CPV cells from Emcore (Fig. 3) is employed in the development of a state-of-the-art dense array concentrator receiver, which aims at achieving high conversion efficiency and at the same time also reduces the overall cost when operating at high concentrations.
Fig 3: Quantum efficiency of CTJ triple-junction solar cell (Source: Emcore, 2008)
Fig 4: A CPV module by Emcore with 1 � 1 cm2 designated aperture area.
Methodology of Research
The design and development of the new dense array CPV module can be divided into three phases and are outlined below:
Phase I: Design of the dense array CPV module
The fundamental study of dense array CPV module starts with circuitry design and analysis where the behavior of the module with series and parallel connections under high concentration levels is examined. In order to optimize its performance especially in the application of a planar concentrator system, all considerations are carefully analyzed including concentration level, uniform illumination area, shading, temperature effect, and mismatch losses.
Phase II: Research and development on the assembling of the CPV module
Assembling the CPV solar cells into a module that can be incorporated with the new planar concentrator is a very challenging research work at this moment and the technology for constructing a compact, robust and high efficiency panel is very critical for the success of the whole project. For that, the CPV cells are surface mount to direct bond copper (DBC) substrate. The back contact of the DBC substrate is to be attached to a cooling block by using heat conductive adhesive. Then, the next step is to wire bond the cells to connect the top contacts to the substrate. To provide the CPV cells with mechanical protection and isolation from humidity, the cells are then encapsulated and subsequently also attached with anti-reflective cover glass.
Phase III: Testing and analysis of the new CPV module
The module is to be analyzed by testing it under laboratory condition as well as in a planar concentrator system operating under Malaysian conditions. The I-V curve of the module can then be plotted to show the maximum power point and its performance efficiency.
