Performance analysis of a micro gas turbine and solar dish integrated system under different solar-only and hybrid operating conditions

•On and off-design model for dish and micro gas turbine solar power generators.•Operating modes include solar-only and hybrid operation with variable fuel share.•Solar-to-electric efficiencies range from 16.78% to 18.35%.•Capacity factors range from 29% to 65%.•Specific emissions in hybrid mode range from 100 (low fuel share) to 475 g/kW h.

A hybrid energy system comprising a parabolic dish solar energy concentrator (Solar Dish) and a micro gas turbine is investigated in the study. A thermodynamic model of the system is presented, able to simulate both on-design and off-design performance of the system and accounting for the main technical aspects of the concentrator, receiver and gas turbine engine. Then, simulations are performed for various system sizes and operating strategies, with and without supplementary firing and for a reference location (Seville, Spain), yielding solar-to-electric power conversion efficiencies between 16.78% and 18.35% (rated conditions), depending on size. Annual performances result in a capacity factor of about 29% (2540 full operating hours) in solar only operation and annual average efficiency at 95% of the nominal value.The main results indicate that moderate supplementary firing is interesting for it increases the average efficiency of the system and the annual yield, whilst still keeping the carbon footprint within reasonable values. Nevertheless, as heavy fossil fuel firing is adopted, the system becomes less competitive against conventional, standard distributed generation power systems either for natural gas or diesel fuel. Whilst these trends were somehow to be expected, the interest of this paper is to provide the reader with a fundamental analysis from which a technical and economic analysis can be performed, aimed at identifying the most leveraged solar share (i.e., fuel utilisation).