Smart energy systems seem a promising choice for countries worldwide to realign their power systems to the challenges predicted for the next decades. With the will to participate in this class of systems, many solution providers design custom systems, which sometimes consist of similar parts, but are on the contrary hard to compare to each other. However, a reference describing existing commonalities is needed as a basis for many activities such as regulation design, legislation, national discussion or standardization. This paper illustrates the challenges connected with the creation of reference architectures for smart energy systems, delineates their benefits and suggests a model and method for their incremental, bottom-up development and validation through concrete system architectures.Index Terms-Reference Architecture; Smart Energy Systems; Smart Grid; Ontologies; Conceptual Modeling; Domain Modeling; Bottom-up design;
I. INTRODUCTIONThe existing energy systems will go through major changes within the next decades. Facts like the increasing of renewable, decentralized energy sources, the growing number of electric cars, national efforts on market liberalization and reduction of CO 2 -emissions, integration of different energy grid types (e.g. electric power, district heating or gas grids) or the need for advanced monitoring systems and increased power stability will drive this change. Many countries discuss new concepts to solve problems like the fluctuating supply of renewable energy with smart systems while having to ensure power stability.As a reaction to this worldwide trend, many actors think of a new class of systems, often labeled as "Smart Energy Systems" (SES) and develop new systems inside this class. However these systems focus on different aspects of the energy system, involve different stakeholders, include new components, functions and data structures and use different technologies, concepts, terminology and infrastructure. The class of SES comprises a variety of systems used in home appliances, energy management, district heating, intelligent devices, virtual power plants, demand side management, market places, data platforms, metering infrastructure, field devices, portal software, weather forecasting or grid operations.Many countries, national and international organizations are interested in SES, as this class of systems is expected to have an impact on national grid infrastructure, markets, customers and industries. In contrast the sheer amount of existing systems and their different architectures complicate the comprehension and comparison of different solutions or the elaboration of an abstract view on SES.