The new version of the Technical Paper DITE 8.03 “Solar Thermal Instalations for Domestic Hot Water”, published by ATECYR, is a revised edition that includes the new Building Technical Code (Código Técnico de la Edificación - CTE). Its recent entry into force requires, except in a few justified cases, that all buildings with DHW have solar thermal instalations that ensure part of this service. It will increase the use of this kind of installation, meaning that in a near future this technology will improve, as well as the technical qualifications of such professionals as project designers and technicians. Therefore, this paper aims at organizing and updating the description of the available technology and the main concepts used in the sector.