Feasibility of off-grid housing under current and future climates

Abstract

This study evaluates the feasibility of off-grid operation of fully electric housing under current and future global warming climates through case studies using building simulations. The case studies were carried out for two house types with different sizes and construction materials, under two typical occupancy patterns (occupied full day and evening only), in seven cities chosen to be representative of a broad range of climates. The study examined three operational scenarios: off-grid operation using PV and batteries; off-grid operation with PV, battery and petrol generator; and grid-connected net zero energy operation.Results show that for the houses being powered by electricity only in warm and moderate climates, large PV battery systems are required to achieve off-grid housing using PV and batteries only, and that payback periods are longer than 15.8 years under current and projected future climates considering replacement cost of battery storage, and projected inflation, discount rate and electricity price escalation rate. Off-grid operation with PV and batteries is economically unviable in heating dominated regions. The study shows that when a PV battery system is hybridized with an on-site petrol generator, the payback periods can be reduced significantly, and it may become economically feasible to operate off-grid with PV, battery and generator for both house types under most occupancy scenarios in moderate and warmer climates, but may still not be economically viable in colder climates. The case study also demonstrates that a grid-connected net zero energy home is economically feasible for all seven cities studied, and more economically attractive than a fully off-grid house under both current and projected future climates, even without subsidies for solar feed-in tariffs.