Cogeneration in buildings coupled with PV system: Case study and Technical feasibility

Power shortages have become common in Lebanon due to the ongoing economic crisis, resulting in intermittent and unreliable energy supply from both the national grid and distributed diesel generators. This situation has accelerated the adoption of photovoltaic (PV) systems in residential applications, as they offer a practical solution for improving energy security and reducing utility costs. However, high-rise residential buildings face a major challenge which is the limited roof area for PV panel installation. To address this issue and optimize further on energy demand, this paper presents a case study of a hybrid energy system for two high-rise residential buildings in Beirut that combines rooftop PV panels and cogeneration from the tower’s diesel generator. The synergy between waste heat recovery and PV installation enhances both thermal and electrical energy production. This study shows that the proposed system results in an annual decrease of 60,824 kWh in energy consumption, representing a 43.7% reduction in total energy use and a 36.7% savings in fuel usage. The proposed configuration can be expanded to larger-scale projects such as hospitality, healthcare, educational and commercial applications.