A solar energy conversion system may include a receiver with a first heat transfer fluid channel having at least two opposite sides. Each side may present an external surface facing in a direction opposite to that of the external surface of the other opposite side. Each side may be configured to contact a heat transfer fluid carried in the first heat transfer fluid channel. A heliostat field may be configured to direct solar energy to each of the at least two opposite sides during the course of a day such that a thermal stress tending to bend the channel remains below a specified level.