Natural sunlight Offers:a cost-efficient and sustainable energy source for photochemical reactions. In contrast to the lengthy and small-scale "flask in the sun" procedures of the past, modem solar Concentrator systems nowadays significantly shorten reaction times and enable technical-scale operations. After a brief historical introduction, this review presents the Most important solar reactor types and their successful application in preparative solar syntheses. The examples demonstrate, that solar manufacturing of fine chemicals, is technically feasible and environmentally sustainable. After over 100 years, 'Ciamician's prophetic:Vision of "the photochemistry' of the future" as a clean and green Manufacturing methodology has yet to be realized. At the same time, his warning, "for nature is not in a hurry but mankind is" is still valid today It is hoped that this review will lead to a renewed interest in this truly enlightening technology, that it will stimulate photochemists and photochemical engineers to "go back to the roots onto the roofs" and that it will ultimately result in industrial applications in the foreseeable future.