ABSTRACT The phenomenon of rapid expansion of global systems of communication (GSM) is observed in several nations around the globe. The expansion of some regions, particularly in developing nations like Port Harcourt, has encountered several obstacles, with one prominent being the inadequate provision of public electricity. The energy cost of the diesel generating set and the PV system in terms of initial capital cost, future replacement, and maintenance cost for the first fifteen years were estimated. This study evaluates the comparative cost analysis of the use of solar energy from solar PV as the source of power against the Diesel generator being used at Airtel Switch Port-Harcourt. Cost analysis was conducted for short-term (5 years), mid-term (15 years), and long-term (25 years). It was found that solar PV was 84.4%, 89.9%, and 87.7% more cost-effective for a 5-year, 15-year and 25-year period respectively. Therefore, considering the cost analysis for short, mid, and long-term operations, excluding inflationary trends, cost of maintenance of diesel generators, oil change, and any other equipment change, Solar PV was found to be more cost-effective as the source of power supply at Airtel Switch Base, Port Harcourt: Solar PV, Short-term, mid-term, long-term, cost-effectiveness. The analysis indicated that, in terms of cost and environmental friendliness, the PV system was the better option to be selected as an alternative and sustainable to the grid supply energy for power generation. Renewable sources have a lower power generation cost than diesel power generation. The adoption of renewable energy as a power source for GSM stations in Nigeria is therefore strongly advocated to make the industry globally competitive.