Impact of different South African demand sectors on grid-connected PV systems' optimal energy dispatch under time of use tariff

For the past few years, the South African government has been promoting the use of solar energy system which can be of benefit to the development of small power producers dispersed throughout the local grid. This support from the government usually comes with an obligation for the main electricity supplier to purchase the excessive power produced by small independent generators. In this paper the impact brought by different demand sector profiles on the daily operational cost and optimal scheduling of grid connected photovoltaic systems with bidirectional power flow is analysed for the specific case of Bloemfontein in South Africa. For this purpose, residential, commercial and industrial daily load curves are used to estimate daily load demands. For comparison purposes, three load profiles representing the demands from the residential, commercial and industrial sectors, have been used and normalized to display the same daily energy consumption level with different demand patterns. The results of the simulations, obtained using Matlab 2016, have revealed that for the same energy consumption and renewable resources, the running expenses of any proposed scheme are mainly dependent on the demand sector. Consequently, it can be recommended that in Bloemfontein and South Africa in general more focus should be on implementing grid-connected renewable technologies with storage systems on the commercial and industrial sector instead of on the residential sector.