Solar versus fossil fuels : A net energy analysis of domestic solar hot water systems in Australia

It is commonly assumed that solar hot water systems save energy and reduce greenhouse gas emissions compared to conventional electric and gas hot water systems. Very rarely has the life-cycle energy requirements (including the embodied energy of manufacture) of solar hot water systems been analysed. The extent to which solar hot water systems can save energy compared to conventional electric or gas hot water systems can be shown through a comparative net energy analysis. This method determines the ‘energy payback period’, including consideration of the difference in operational energy savings and energy embodied in the devices relative to a base case. Dr Robert Crawford, Deakin University, Australia presents the results of a net energy analysis that compared solar and conventional hot water systems for a southern (Melbourne) and a northern (Brisbane) Australian climate.