Disclosed herein is a solar reactor comprising a reactor member; an aperture for receiving solar radiation, the aperture being disposed in a plane on a wall of the reactor member, where the plane is oriented at any angle other than parallel relative to the centerline of the reactor member; a plurality of absorber tubes, wherein the absorber tubes are oriented such that their respective centerlines are at an angle other than 90.degree. relative to the centerline of the reactor member; and wherein the aperture has a hydraulic diameter that is from 0.2 to 4 times a hydraulic diameter of at least one absorber tube in the plurality of absorber tubes; and a reactive material, the reactive material being disposed in the plurality of absorber tubes.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR SUPPORT
 This invention was made with government support under Contract Number DE-AR0000184 awarded by U.S. Department of Energy/Advanced Research Projects Agency-Energy (ARPA-E). The government has certain rights in the invention.