Adaptation of residential solar systems for domestic hot water (DHW) to hybrid organic Rankine Cycle (ORC) distributed generation

Abstract

Among the portfolio of energy systems for local power generation, Organic Rankine cycles (ORCs) for residential applications are an opportunity for local cogeneration based on synergies with existing thermal heating and storage systems. They can be highly competitive for isolated installations and the refurbishment of existing solar heating installations based on solar domestic hot water. This article evaluates the potential for hybrid solar ORC integration in residential buildings. The analyses focus on the annual yields of a domestic 1 kW ORC cycle to assess the advantages and disadvantages of the variation of demand and the availability of solar resources. The models are developed, integrating TRNSYS and EES to allow a detailed evolution characterisation. Performance and impact of CHP adaptation are considered based on demand, storage volume-collectors area ratio, and production strategies. The analysis is completed with a thermo-economic analysis under different ranges of thermodynamic parameters. Positive IRR results of 8.61% are obtained for the installation located in Seville, Spain, operating the ORC 15% of the year. It also reduces the overheating associated with the lack of heat demand and excess solar irradiation in the solar system for the warm months by 20%.