This paper explores the performance advantages of a novel design of an evaporator-superheater for Rankine solar applications. The solar absorber device consists of a dual-chamber design in which the outer chamber contains fins for enhanced heat transfer allowing for multi-pass working fluid to accomplish both single phase and multiphase heat transfer in a simple low-cost manner. Analytical models to predict heat transfer performance and frictional losses in this design are described. Nondimensional analysis compares multiple strip-fin configurations for the outer chamber to establish optimal constructions. Predicted performance of the dual-chamber design is compared to traditional single chamber solar absorber tube for a 10 kW case study. The design analysis indicates that the concentric dual-chamber design minimizes heat loss to the surroundings providing a high level of evaporator performance. Copyright © 2011 by ASME.