Solid particles have previously been proposed as an alternative to molten salt as a heat transfer and heat storage medium for concentrating solar power plants. While previous solid particle solar receiver designs use fluidized or falling particles, the new type of receiver proposed in this thesis uses a gravity-driven flow of particles in a dense granular flow regime. Through experimentation with sand, the flow and heat transfer properties were studied in two geometries: vertical tubular and vertical parallel plate. The effective thermal conductivity of the flowing sand, calculated from experimental results, was used to model a 5 by 5 meter square, finned solar receiver in ANSYS Fluent. Four different fin configurations were modeled with two levels of uniform radiative flux. One fin configuration was studied using a concentric radiative flux distribution with a peak of 600 kW m-2, and results show an overall thermal efficiency of 66.5% and a maximum temperature of 1047˚C reached on the absorber surface.