The present paper analyzed the thermal performance and control optimization of a solar system based on seasonal sorption storage for domestic applications. The system control, which could choose between 41 operational modes, was optimized based on operational costs and maximization of sorption system use. The system was composed by 17.5 m2 of evacuated tube collectors, 3.6 m3 of composite sorbents based on lithium chloride and a stratified water tank. High efficiency of a sorption storage system was obtained when continuous charges or discharges occur, which, in this study, depended on weather conditions (ambient temperature and solar irradiation). The operational economic benefits were maximized using a sorption system with 9% less capacity and, therefore, less storage volume. The sorption thermal energy storage system obtained energy densities of 90 and 106 kWh/m . The whole system could supply 35% of the total thermal demand of a single family house in Nuremberg. The study concluded that the control optimization of a seasonal sorption system is a key factor to make the technology competitive, define its optimal size and, therefore, maximize its energy density in further designs. This project was funded by the European Union’s Horizon 2020 Research and Innovation Programme under grant agreement No. 764025 (SWS-HEATING). This work was partially funded by the Ministerio de Ciencia, Innovación 𝑦� Universidades de España, Spain (RTI2018093849-B-C31–MCIU/AEI/FEDER, UE) and by the Ministerio de Ciencia, Innovación 𝑦� Universidades–Agencia Estatal de Investigación (AEI) (RED2018-102431-T). The authors would like to thank the Catalan Government for the quality accreditation given to their research group (2017 SGR 1537). GREiA is certified agent TECNIO in the category of technology developers from the Government of Catalonia. This work is partially supported by ICREA under the ICREA Academia programme. Alicia Crespo would also like to acknowledge the financial support of the FI-SDUR grant from the AGAUR of the Generalitat de Catalunya and Secretaria d’Universitats i Recerca del Departament d’Empresa i Coneixement de la Generalitat de Catalunya. Peer Reviewed