Dual-towers are 1.5 points more optically efficient than single-towers.

Tower selection algorithm enhances the field cosine factors by 3.5 points.

Spillage losses computed with a novel cone-tracing model.

Difference with SolTrace: 0.43% (spillage) and 0.84% (shading and blocking).

Optimized heliostat fields exceed the preliminary ones by up to 5.9 points.


Solar tower systems show significant prospects based on their room for improvement in the solar thermal industry. Despite not being an entirely new concept, multi-tower systems have not been extensively studied in the literature yet. An optical optimization model is presented to evaluate the feasibility of dual-tower systems, where each heliostat can select the most convenient receiver. There is a number of optimization variables, which makes it essential to implement a fast optical algorithm capable of evaluating the field optical efficiency. Taking advantage of the tower central receiver’s axial symmetry, an integration method is proposed to work out the individual spillage for each heliostat. As a result, an optimal design has been accomplished where 32 representative days (with several time-points each) have been taken into account to assess the yearly-averaged optical efficiency of the whole solar field. Thus, it can be concluded that a ∽1.5% increase in the annual optical efficiency can be achieved with respect to the analogous single tower system.


Energy Systems Engineering Group (ISE), Department of Thermal and Fluid Engineering, Universidad Carlos III de Madrid, Av. Universidad, 30, 28911, Leganés, Madrid, Spain
Universidad de Málaga, Escuela de Ingenierías Industriales, Campus de Teatinos S/n, E29071, Malaga, Andalusia, Spain