A boiler for a solar receiver includes a plurality of boiler panels arranged side by side with each other so that the panels form a boiler wall section. Piping fluidly connects the plurality of boiler panels together to route a working fluid through the boiler wall section from an inlet of the boiler wall section to an outlet of the boiler wall section. The piping and boiler panels are configured and adapted to route the working fluid through each of the boiler panels in a common direction.