The activities of the Solar & other Energy Systems Laboratory (SESL) started in NCSR "Demokritos" by the late A. Delyiannis, Professor of Chemical Engineering at the National Technical University of Athens and the current Director of the Laboratory Dr. V. Belessiotis at the end of the 1970's. The focus at that time was on solar desalination, the development of thermal electric power generating plants and mechanical, agricultural product driers using hot air. Subsequently, and up to the beginning of the 1990's, emphasis was placed on the development of methodologies for the characterization and performance evaluation of Thermal Solar Collectors and Domestic Hot Water Systems, an activity which led to the creation of the relevant international ISO standards. Over the same period, the infrastructure for the testing of such devices and systems was developed, allowing for the evaluation of the entire set of solar collectors and systems manufactured by the national industry, aiming at the characterization and the design optimization of the products. This was an important development for the domestic manufacturing branch of solar thermal products.
In the decade of 1990's, a significant further development of laboratory infrastructure took place, with a parallel establishment of a Quality Assurance System, while SESL also contributed to the growth of the concept of Quality in Greece through the relevant institutional bodies, National Accreditation Council (ESYD), market regulation, Association of Greek Laboratories (HellasLab) etc.
Finally, starting in the decade of 2000's and up until now, emphasis has been placed on Research & Development activities, with main areas of focus: solar collectors & systems, analysis & design of thermal storage systems, solar cooling, thermal distillation-desalination, mechanical/solar-assisted drying processes and systems, metrology of energy quantities, and computational fluid dynamics and heat transfer.
Parallel to these activities, the Accreditation of the Laboratory Infrastructure was pursued, originally according to the EN45001 standard and later on to its successor, the ELOT EN IOS/IEC 17025 Standard. It should be noted that SESL was the first laboratory in the research-academic sector in Greece to obtain this accreditation and one of the first such at European level.