Comparison in net solar efficiency between the use of concentrating and non-concentrating solar collectors in solar aided power generation systems

Solar Aided Power Generation (SAPG) technology offers the promise of a higher energy efficacy and lower carbon emissions. In virtually all pilot-scale SAPG projects, concentrating solar collectors (e.g. parabolic trough collectors) are used to produce solar heat with a temperature ranging from 300 °C to 350 °C, to replace the feed water pre-heating in high pressure feed-heaters (HPH) in regenerative Rankine steam cycles. Although concentrating solar collectors offer a higher solar thermal efficiency, whether the use of this type of solar collector in a SAPG system can still offer both higher net solar thermal and net solar to power efficiencies remains unknown. This paper investigates the performance of an SAPG with either concentrating collectors or non-collectors (evacuated tube collectors). It was found that non-concentrating collectors are able to generate more power through the SAPG mechanism and exhibit higher net solar efficiencies than concentrating collectors on the per unit land area basis. This outcome suggests that the use of non-concentrating collectors in SAPG systems is more efficient than the use of concentrating collectors.