This study presents the design and techno-economic optimization of a 10.2 kWp grid-tied hybrid photovoltaic (PV) system for residential applications in Owerri, Nigeria. The objective is to develop a reliable and cost-effective solar power solution capable of mitigating dependence on the unstable national grid. Household energy demand was estimated based on the daily consumption patterns of common appliances and their average operating hours. Using analytical design methods, appropriate PV, inverter, and battery capacities were selected and optimized to enhance overall system efficiency. The final configuration comprises twenty 510 W monocrystalline PV modules (10.2 kWp total capacity) coupled with a 10 kW hybrid inverter, yielding a DC/AC ratio of approximately 1.02. Under typical meteorological conditions in Owerri, the optimized array is projected to generate about 36.72 kWh per day. Economic analysis, based on a capital cost of N6.6 million, annual maintenance of N66,000, a 20-year lifetime, and a 7% discount rate, indicates a levelized cost of electricity (LCOE) of approximately N30.5 /kWh and a simple payback period of 7.5 years. The results demonstrate that with realistic load estimation and properly matched components, small-scale PV systems can offer a technically feasible and economically sustainable alternative to grid electricity in Nigeria’s residential sector.