The mobile commerce of applications integrating solar thermal collectors, together with their configuring applications, has started to develop. Such applications are not only a business opportunity but also a sustainable and feasible solution for energy consumers who are more and more digitalised. This paper focuses on understanding behaviours in niche markets formed by small-sized and/or isolated consumers who need customized, sustainable and economically efficient applications for heating water for domestic and business use. We chose the focus group interview as the method of research. Primary data were collected in Romania and analysed with Atlas.ti 8. Firstly, the results revealed that consumers’ behavioural changes needed for switching to solar energy are influenced by their attitude regarding investment in this market as well as by the perceived social influences and control. Secondly, the results showed the effort paradox of small-sized and/or isolated users of applications integrating solar thermal collectors who shall be considered by developers and sellers alike in providing them with water heating solutions. In terms of business implications, we highlight that the cost-reduction strategy within enterprises is to go green, so major investments in solar technology in order to become energy independent and self-sufficient are envisaged on the long term, whereas the use of digital applications integrating it requires a high level of staff’s digital skills and the use of smart devices.