Techno-Economic Comparison of Vehicle-to-Building Lithium-Ion Battery and Diesel Generator Systems for Smart Building Backup Power Using HOMER Pro

The transition toward a low-carbon energy system is driving the development of smart buildings that require reliable, environmentally friendly backup power systems. Diesel generators remain the dominant option despite their fossil-fuel consumption and emissions, while Vehicle-to-Building (V2B)-based Lithium-ion battery systems offer a promising but underexplored alternative, particularly in Indonesian smart buildings. This study evaluates the techno-economic feasibility of a V2B-based Lithium-ion battery system as an alternative backup power source, using HOMER Pro to model a representative five-story office building (977 m²). Two configurations were compared: Grid + Diesel Generator and Grid + V2B-based Lithium-ion Battery, assessed technically, economically (Net Present Cost, Cost of Energy, Operating Cost), and environmentally. Results show the V2B system can supply backup power for 4.10 hours and eliminate diesel fuel consumption by 100%, but produces 61.2% higher NPC, 65.7% higher COE, and 36.8% higher operating cost, with only a 0.18% reduction in CO2 emissions. Although not yet the most economical alternative, the V2B system significantly enhances building energy resilience and represents a promising pathway toward cleaner backup power as battery costs decline and electric vehicle adoption increases.