Techno-economic analysis for constructing solar photovoltaic projects on building envelopes

Solar energy applications in buildings are crucial to urban sustainable development and commercial energy investment. Increased environmental and economic awareness, coupled with local governmental incentives, inevitably causes a growth in construction of photovoltaic (PV) projects. Previous studies extensively explored and developed life cycle energy assessment and costing analysis for payback times of rooftop PV systems. This paper presents a new methodology that combines a life cycle cost (LCC) approach and a pixel method for visualising economic performances of constructing PV projects. The time of recovering the expenditure invested in a PV project is then considered a main economic indicator and is formulated mathematically in the pixel unit representing an actual area of 3 cm x 3 cm in an empirical study. A building model derived from a real student accommodation is then chosen as a case study in this paper. The 3D visualisation demonstrates a potential investment return for placing each solar panel on a specific site over roofs and facades. The proposed contour lines of economic returns also illustrate the optimum ranges for constructing potential PV projects with desirable payback periods during their lifetimes. Results reveal that the facade installation is sometimes competitive with the roof-top installation. This study will benefit designers and construction managers in determining the optimal solution of implementing the rooftop and fa ade PV systems in the phases of design and construction.