Solar energy has been widely introduced in the building market to provide electricity, heating and domes-tic hot water for a sustainable development. However, the low-density and the mismatch between energysupply and demand make appropriate its combination with thermal energy storage (TES) systems. Theintegration of these technologies (solar thermal and TES) in the building design is a key aspect to reduceenergy consumption. Latent heat storage using phase change materials (PCM) presents an advantage incomparison to conventional sensible heat storage systems due to the required volume. In this context,an innovative system that integrates PCM inside the structural horizontal building component is pre-sented in this paper. The slab consisted of a prefabricated concrete element with 14 channels filled withmacro-encapsulated PCM which is used as a storage unit and a heating supply. In order to melt the PCMthe system is coupled to a solar air collector. The prototype is tested in an experimental facility locatedin Puigverd de Lleida (Spain) where its thermal performance is evaluated under real weather conditions.This study demonstrates the high potential of the concrete slab on reducing the energy consumptioncompared to a conventional heating system. The work partially funded by the Spanish government (ENE2015-64117-C5-1-R (MINECO/FEDER), ENE2015-64117-C5-3-R (MINECO/FEDER), and ULLE10-4E-1305). The authors wouldlike to thank the Catalan Government for the quality accreditation given to their research group (2014 SGR 123) and thecity hall of Puigverd de Lleida. This project has received fundingfrom the Eurpean Commission Seventh Framework Programme(FP/2007-2013) under Grant agreement Nº PIRSES-GA-2013-610692 (INNOSTORAGE) and from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 657466 (INPATH-TES). Alvaro de Gracia would like to thank Ministerio de Economia y Competitividad de España for Grant Juan dela Cierva, FJCI-2014-19940.