The main object of this paper is the documentation and study of the main factors behind the spectacular diffusion of solar energy use for domestic hot water production in Greece. The time pattern of the diffusion of flat-plate solar collectors since its 'out of the blue' first appearance in 1974, shows that the diffusion rate grew exponentially at first, with the annual sales figure reaching 91,000 m(2) by 1980. A rate slow down in the early 1980s was followed by a brief period of explosive growth, with the annual sales figure reaching its peak value of more than 185,000 m(2) in mid-1980s. A rapid decline of the growth rate down to the present annual sales level followed. The installed solar collectors pattern has the characteristic form of an S-shape curve, representing the overall penetration of the flat-plate solar collector use for domestic hot water production in the Greek economy and society. This evolution has gone through an inflection point around 1987, i.e. at a time when about 1,000,000 m(2) Of Col- lectors had been already installed. By the year 2000, about 2,070,000 m(2) of collectors had been installed, with a tendency to level off by 2010, unless some of the present conditions determining this phenomenon change. (C) 2004 Elsevier Ltd. All rights reserved.