Rapid urban growth poses distinct energy and environmental challenges in various regions of the world. This study evaluated the technical and economic feasibility of a grid-connected photovoltaic system in Santo Domingo Tehuantepec, Oaxaca, Mexico, using Homer Pro software, version 3.14.2, to simulate realistic scenarios. The analysis incorporated local climate data, residential load profiles, and updated economic parameters for 2024. System optimization resulted in an installed capacity of 173 kW of solar panels and 113 kW of inverters, yielding a levelized cost of energy (LCOE) of MXN 1.43/kWh, a return on investment (ROI) of 5.3%, an internal rate of return (IRR) of 8%, and a simple payback period of 10 years. The projected annual energy output was 281,175 kWh, covering 36% of the local energy demand. These results highlight the potential for integrating renewable energy into urban contexts, offering significant economic and environmental benefits. The integration of public policy with urban planning can enhance energy resilience and sustainability in intermediate cities. This study also supports the application of tools such as Homer Pro in designing energy solutions tailored to local conditions and contributes to a fair and decentralized energy transition.

Electricity purchase price variation can influence the economic feasibility of residential distributed generation, particularly in regulated markets where grid electricity prices and export compensation conditions affect investment decisions. This study evaluates the impact of flat electricity purchase price scenarios on the techno-economic viability of residential grid-connected energy systems in Santo Domingo Tehuantepec, Oaxaca, Mexico, using HOMER Pro. The analysis considers PV, wind generation, diesel generation, converter, and grid connection as candidate components, while evaluating three residential demand profiles of 11.26, 30.00, and 83.30 kWh/day and 10 electricity purchase price scenarios ranging from 3.45 to 5.00 MXN/kWh. The objective is to identify the electricity purchase price values at which the optimal architecture changes from conventional grid-only supply to PV/converter/grid adoption under the evaluated case study assumptions. The results show that grid-only supply remains the least-cost option from 3.45 to 4.20 MXN/kWh for all demand profiles. At 4.25 MXN/kWh, HOMER Pro selects PV/converter/grid configurations for the medium- and high-demand profiles, while the low-demand profile remains grid-only. At 4.30 MXN/kWh, PV/converter/grid also becomes optimal for the low-demand profile. At 5.00 MXN/kWh, ROI reaches 11.0% for the three residential demand profiles, while payback decreases to 6.5 years for the low- and medium-demand profiles and 6.4 years for the high-demand profile. The wind turbine and diesel generator were not selected in the optimal configurations, despite being included as candidate technologies. These findings provide a practical case study indicator of the electricity purchase price levels at which residential PV-grid adoption becomes economically competitive under flat purchase price scenarios and zero export compensation.