is derived from one or more of the above sources a temperature 275 of the expander 202 inlet will change only slightly as the actuator 278 works to maintain the optimal temperature 270 at the dish module 201 an alternative heat source for the air heater 203 is a hydrocarbon fuel delivered from a container 284 through a conduit 285 such fuel candidates include for example operation with such fuels requires interaction with the microprocessor controller 277 and permits operation at elevated expander inlet temperatures 275 and improved overall efficiency in response to a change in the optimal expander inlet temperature set point 275 an actuator 279 controlling a valve 286 will be commanded by the microprocessor 277 to make the required correction as this fuel delivery from the vessel 284 is controllable the actuator 279 is a slave to the measured or inferred temperature at state point 270 in the solar power conversion module 205 peak overall efficiency may be maintained by adjusting the circuit flow rate through the turbine and expander using actuator 278 such that temperatures 270 and 275 remain as close to their maximum set point as the external variables see table 1 change an alternative schematic for the central power generator 232 is shown in fig2 rather than producing electric power the central power generator 232 delivers shaft power directly to an air compressor 234 the necessary pressure let down and flow control functions provided by the expander 235 to control the dish module 201 remain the same as previously described in fig1 and 20 the compressed air produced from the expander 235 power is delivered at the pressure demanded by the solar power conversion module 205.