In the era of the Internet of things, billion of smart objects are going to be connected, with the needs of producing and storing big amount of data. In this context, there are many drawbacks to overcome related to data storage, processing power and connection capabilities of physical devices. This paper focuses on the specification of virtual sensors (VSs) as abstraction of real sensors, reproducing their logical behavior and enriching their functionalities within the cloud platform. The use of VSs is presented with the goal of proposing innovative services for stakeholders in the electromobility framework. To this purpose, a methodology to describe and implement VSs is presented based on Unified Modeling Language diagrams and a useful VS is designed for electromobility enhancement, that is, charge price prediction VS.