Increasing population forces us to find the best ways of using the existing energy resources. In search of the best ways there is a higher need for optimisation applications. It is observed that applications in the energy fields are mainly focused on minimizing the investments, maximizing the efficiency of technological designs, and minimizing the operational costs. Operations scheduling or load planning as named in the energy field, is important in minimizing the operational costs. Besides, scheduling is one of the basic fields of operations research that is why it is a field of continuous improvement in line with the changes in the energy field. This research aims to analyse the scheduling literature to depict the subjects least studied. Our article handles the publications of research on scheduling with the objectives, decision variables, constraints, methods and the achievements. Furthermore, the uncertainties handles in primal energy or renewable energy utilization are covered by the analysis performed. The scheduling optimization studies found in literature is clustered using self-organizing maps (SOM) in order to observe the frequency of subjects analysed. This study confirming the literature survey and clustering of existing studies will lead the researchers working on energy systems scheduling.