The increasing demand for energy and the need to transition to renewable sources has led to a growing interest in the use of solar energy. This paper conducts a comparative analysis of the economy and reliability of pure solar energy systems and utility supply in a small load area. The energy requirement of the chosen load area was estimated and the appropriate sizing of the solar system was made. The study uses the payback period method to estimate the economy and the Monte Carlo method to estimate the reliability. Load estimation was performed to determine the appropriate solar systems, which were then modelled using PVSyst. The results of the study show that solar energy can be a cost-effective and reliable alternative to utility supply; with a consistent maintenance cost of 4 % per annum, the return on investment was calculated to be 14.1 % per annum at a supply current tariff of ₦ 61.34 per kWh. The payback period showed that the investment in a solar photovoltaic (PV) system can be recovered in six years and nine months (6 years, 9 months). The Monte Carlo simulation demonstrated the reliability of the energy supply in a solar PV system compared to the Nigerian utility supply with the reliability index of the solar system being 93.81 % and that of the utility supply at 55.73 %
