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Development of a photovoltaic array simulation tool for shading and mismatch evaluation

McRae, David (2009) Development of a photovoltaic array simulation tool for shading and mismatch evaluation. Other thesis, Murdoch University.

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    Abstract

    This dissertation explores the development of a simulation model in ICAP to illustrate the effects of shading and mismatch of photovoltaic cells within a photovoltaic array. The intention of designing the simulation model was to build a simulation tool which could be utilised as a teaching resource for illustrating the effects of shading and mismatch of photovoltaic arrays for renewable energy engineering education. The process of building such a model initially involved building a single cell in ICAP which was based on a single diode model to illustrate the current and voltage output of a single cell. Once the output resembled the output for an ideal I-V curve, the next step was to build several cells in series with the inclusion of two bypass diodes in parallel with a series connection of 18 solar cells per bypass diode.

    To simulate unshaded conditions, the photo-generated current of each solar cell was the same and the output subsequently resembled the same output as that for an ideal I-V curve. Shaded conditions were simulated by reducing one of the solar cell photo-generated currents by half the original current value. The resulting output had an unchanged short circuit current and open circuit voltage. However, the overall I-V curve had a changed I-V curve characteristic, as well as a reduced power output.

    Once a module of 36 cells with two bypass diodes was constructed in ICAP, testing was conducted in the Spi-Sun Simulator 460 at the Remote Outdoor Testing Area (ROTA) compound to simulate the outputs for a mono-crystalline module with and without bypass diode connections as well as for unshaded and shaded conditions. The current and voltage results from the simulation were then converted to a Microsoft Excel file. Curve fitting was performed to obtain modified parameters to input back into the module model in ICAP. The modified parameters were then input back into the model in ICAP to illustrate the I-V curve outputs for a module with and without bypass diode connections as well as for unshaded and shaded conditions.

    The outputs from the ICAP simulation were then exported from the ICAP graph into a text delimited file which was then converted into a Microsoft Excel file. The ICAP results were compared with the ROTA results and whilst the short circuit current and open circuit voltage values were the same, there was some discrepancy with the curve fitting.

    Publication Type: Thesis (Other)
    Murdoch Affiliation: School of Engineering and Energy
    Supervisor: Calais, Martina
    URI: http://researchrepository.murdoch.edu.au/id/eprint/3239
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