In the concept of smart grid information exchange between different systems, both within companies and with external partners, is of key importance. An effective integration of IT systems requires in addition to interoperability at the level of communication protocols also interoperability at the semantic level, an appropriate integration architecture and a standardisation framework. Without this, the concept of smart grid cannot be effectively implemented. Although the standardisation framework is already available, the implementation of semantic technologies for systems integration in the power utility companies is new to these companies. Extensive development, implementation and organisational efforts will be required. The work presents the issues of information systems integration within the scope of smart grid and proposes integration concepts for most common use cases which are aligned with the European Smart Grid Reference Architecture.