This study presents a combined flat plate heat receiver (FPHR) for a solar power tower plant. Four flat plate heat pipes (FPHPs) as heat transfer units are homogeneously enclosed in a cavity of 150 constituting the combined FPHR. The start-up characteristics of the FPHP were experimentally investigated and quantitatively analysed. In addition, the isothermal performance, heat transfer performance, stability under severe working conditions, and effect of non-condensable gas on the thermal characteristics were experimentally investigated. The results show that the heat transfer limits are not encountered during the start-up process and the FPHP heated on one-side surface could successfully start up. The continuum flow regime established in the FPHP results in a good isothermal characteristic and makes the output power to synchronously respond to the input power without delay under a heat flux fluctuation condition. It is also found that the FPHP possesses potential to inhibit the hotspots under non-uniform heating condition. Besides, the accumulated non-condensable gas would lead to the reduction of the heat transfer performance. The main conclusions drawn from this work will be helpful for further development of the heat receivers used in solar power tower systems. (C) 2018 Elsevier Ltd. All rights reserved.