Brunei Darussalam is a small country with a population of less than half a million. Despite this fact, Brunei is one of the countries with a high electricity consumption per capita. This large amount of electricity is generated primarily from natural gas, negatively impacting the environment. The country needs to deal with its high electricity consumption immediately. The significant electricity use is divided mainly into three sectors: 1) industrial, 2) residential, and 3) commerce and public service. The residential sector takes almost 40% of the total final electricity consumption. Thus, this paper targets this sector as the population for the study. Since Brunei is a country with high solar energy throughout the year, it has enormous potential to invest in solar PV systems to cover the high electricity consumed by the population. The nation also has residential housing schemes with mostly large rooftop areas, enough to support PV panels. Since rooftop PV systems are popular in many countries but not Brunei, this paper will study the potential electricity the country can generate from investing in rooftop solar PV systems. The study calculated the optimal PV system sizes based on the residential sector's load profiles. The results of this sizing were compared with the available rooftop area of the national housing schemes. Thus, by the end of the study, the paper will present the potential PV systems the nation can invest in based on residential houses. Through this study, future housing planning can consider the valuable potential of investing in residential rooftop PV systems.