An assessment of solar-powered organic Rankine cycle systems for combined heating and power in UK domestic applications

TLDR

The study evaluates the feasibility of a small‑scale solar heat and power system using an ORC for domestic heating and electricity in the UK. The authors model a roof‑sized solar collector array feeding an ORC engine with a positive‑displacement expander and water‑cooled condenser, coupled to a hot‑water storage cylinder, and perform annual simulations, collector‑type comparisons, and cost analyses to assess power output and economics. The system can deliver an average of 89 W (≈776 kWh yr⁻¹) and meet about 80 % of domestic hot‑water demand at a capital cost of £2.7–3.9 k, with PTC and ETC collectors performing similarly.

Abstract

Performance calculations are presented for a small-scale combined solar heat and power (CSHP) system based on an Organic Rankine Cycle (ORC), in order to investigate the potential of this technology for the combined provision of heating and power for domestic use in the UK. The system consists of a solar collector array of total area equivalent to that available on the roof of a typical UK home, an ORC engine featuring a generalised positive-displacement expander and a water-cooled condenser, and a hot water storage cylinder. Preheated water from the condenser is sent to the domestic hot water cylinder, which can also receive an indirect heating contribution from the solar collector. Annual simulations of the system are performed. The electrical power output from concentrating parabolic-trough (PTC) and non-concentrating evacuated-tube (ETC) collectors of the same total array area are compared. A parametric analysis and a life-cycle cost analysis are also performed, and the annual performance of the system is evaluated according to the total electrical power output and cost per unit generating capacity. A best-case average electrical power output of 89 W (total of 776 kW h/year) plus a hot water provision capacity equivalent to ∼80% of the total demand are demonstrated, for a whole system capital cost of £2700–£3900. Tracking PTCs are found to be very similar in performance to non-tracking ETCs with an average power output of 89 W (776 kW h/year) vs. 80 W (701 kW h/year).