Design of a grid connected photovoltaic system for KNUST and economic and environmental analysis of the designed system
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Date
2008-08-08
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Abstract
This research was undertaken to investigate the economic and environmental suitability of the implementation of Grid Connected Photovoltaic Systems in comparison to the use of fuel generators/plant as an alternative source of energy to solve the regular grid failure problem in residential and commercial institutions in Ghana with KNUST as the case study. In this work a 300 kVA grid connected photovoltaic system with 100% battery back up is designed for KNUST. System wiring, installation, maintenance and trouble shooting procedures for the system designed were outlined to show that it is theoretically possible to design a PV grid connected system for KNUST. To simplify the work, the design is undertaken for the 300kVA substation (Ridge substation) and the results are replicated for the remaining substations. The results of this work show that the KNUST Ridge substation requires a 360VDC battery bank with a capacity of 2785Ah (C10 rating). The system requires a 300kVA Trace sun-tied 3-phase Inverter and 1575 of the BP 7180 modules. The total yearly output of the system to the grid is calculated to be 0.296GWh. The 300kVA grid connected photovoltaic system is estimated to cost 2.88 Million dollars. The cost of installing a 300kVA fuel generator is 103,477 dollars. Assuming a loan interest rate of 8% and inflation rate of 12% over a 25 year product life, the calculation of the Average Incremental Economic Cost (AIEC) of the two systems shows that the grid connected PV system has a lower AIEC of 0.67 compared to 12.14 of the fuel generator/plant. This results show clearly that the grid-connected system is economically preferable to a fuel generator of the same capacity as an alternative source of electricity for KNUST.
Sensitivity analysis carried out futher shows that the grid connected PV system is more economical at high inflations rates and longer project life times. Also, the net savings in CO2 by choosing the grid connected PV system over the Fuel generator is 180g/KWh and that makes the grid connected PV system more environmentally suitable.
It is concluded in this work that in the long term the implementation of a grid connected PV system is both economically and environmentally preferable to a fuel generator/plant.
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A thesis submitted to the Department of Electrical/Electronic Engineering, Kwame Nkrumah University of Science and Technology in partial fulfillment of the requirements for the degree of Master of Philosophy.