With regards to the rapid development of renewable energy resources, which is seen as sustainable electricity generating technologies. The costs analysis related to various power supply technologies are critical for business decision making. To this end, the South African government by means of its energy department has signed an agreement to add 2 300MW of renewable energy generating sources, which will be developed by the Independent Power Producer. Thus, this research paper used two different approaches (the Levelized Cost of Electricity (LCOE) and the Levelized Avoided Cost of Electricity (LACE). This latter was developed with the aim of addressing the issues left out by LCOE, which are crucial to business decision making. In this paper, at least 10 different power producing plants (coal, gas, nuclear, biomass, geothermal, hydroelectric, wind offshore, wind onshore, solar photovoltaic, concentrated solar power) were used as case study. The results indicate that of all technologies, geothermal ranks at the first place as the most economic competitive alternative, followed by coal technology. Furthermore, the results illustrate that the worse technologies in terms of economic viability are solar photovoltaic, concentrated solar power, and wind. As far as the authors are aware this study is the first example in the context of the South African energy sector.