This study proposes a design of a trigeneration plant for the usage of Periwinkle Lifestyle Estate in Lagos State Nigeria. The proposed system would provide electricity, heating and freshwater requirements for residential buildings from a renewable energy source. Concentrated photovoltaic solar thermal (CPV/T) collector is used to generate the electricity and provides the required amount of thermal energy to the multistage flash desalination plant and Kalina cycle due to its high electrical and thermal effectiveness. The EES is used to model the tri-generation system by solving the governing equations with an interconnected structure, while TRNSYS and HOMER software was also used to collect the solar data for the case study area. The combined trigeneration structure can produce 0.6412 kg/s of freshwater, 1520.25 kW of electricity generation, and 91.57 kW of heat required for the district heating application, for the usage of Periwinkle lifestyle estate Lagos State Nigeria. The designed system can serve as an alternative to producing high-quality freshwater for drinking and irrigation, reliable and steady electricity and heating services during the winter season, without pollution. • A trigeneration system using CPVT is presented. • The effect of ammonia concentration on the system is analyzed. • The combined trigeneration structure can produce 0.6412 kg/s of freshwater, 1520.25 kW of electricity generation. • The proposed system can meet the electricity, heating and fresh water demands of case study city.