Techno-economic and reliability assessment of solar water heaters in Australia based on Monte Carlo analysis

Monte Carlo analysis is used in this study to estimate the techno-economic benefits and reliabilities of solar water heaters. The study focuses on a product range manufactured by a local company in Australia. The historical data provided by the company forms the basis of this investigation. The inverse Weibull distribution function is a good match for representing the historical data in the model in terms of the number of failures per operating time for each component. The overall system reliability is determined as the sum of individual component failures during the product lifetime. The analysis is carried out for different system configurations using copper, stainless steel and glass-lined storage tanks. All the systems utilise flat plate collectors. The product with glass-lined storage tanks and electric boosters show a good overall reliability if systems are maintained. Based on the probability model, the variable maintenance costs of solar water heaters were estimated over the product lifetime. This together with capital expenditures and fuel charges are used to compute the specific price of hot water supply for different system configurations. Moreover, a sensitivity analysis is implemented to show the impact of auxiliary heating on the economic viability of the products. The results show that solar water heaters can offer significantly better long-term economic viability compared to conventional systems at moderate auxiliary energy consumptions

Life cycle assessment of domestic hot water systems in Australia

Global warming potential (GWP) and primary energy demand (PED) were investigated for a range of domestic hot water systems in Australia, from cradle-to-grave, using streamlined life cycle assessment. The production of the hot water systems was modelled using inventory data calculated using specifications from a range of Australian manufacturers. The use stage of the life cycle was modelled assuming installation within Australian climate zone 3 according to the Australian and New Zealand water heater standard (AS/NZS 4234:2011). The electric storage hot water system had the highest GWP and PED, followed by solar electric, gas storage, gas instantaneous, and then solar gas instantaneous system. The solar hot water systems were shown to significantly reduce the GWP and PED compared to their non-solar counterparts, despite the additional impacts associated with production. The use stage accounted for 87%–99% of the GWP or PED of all systems. GWP and PED payback periods were less than 12 months for the solar hot water systems