Energy system components are modular in nature and interact across multiple scales. There is a need for a modelling framework that can easily construct and configure systems of modular entities (energy demands, sources, converters, storages and network links). These systems should be hierarchically nestable, facilitating the construction of large systems at high levels of detail. The framework should also facilitate the approximation of sub-systems, to aid model solvability. The above framework should be implemented in an object-oriented fashion, making use of the modular >>Open Energy System Modelling Framework<< (Oemof). Components should be specified in a common format that integrates with a database of available entities. The implementation should allow particular systems to be duplicated and reconfigured as well as reused as subsystems in larger models. Configuration parameters of multiple sub-systems should be readable from an external table.