Systems of systems typically contain many technical systems but also span across and affect different legal and economic entities (e.g., companies, public bodies, etc.). The economic entities are involved in exchanges of goods, services and value. To develop an envisioned or to understand an existing system of systems, systems engineers should also be able to model and analyze these value exchanges and the business interactions related to them. Business interactions are strongly related not only to the requirements on the systems of systems, but also on the systems within them. In this paper we propose to use business models, business process models and value network models to analyze business interactions in the context of systems engineering, and to elaborate how they can be related to requirements. We examine our proposal on an example system of systems: a smart grid.