Energy is a difficult concept to be understood by students of all levels. Thus, the aim of the study is to determine how high school students at different levels perceive the energy and related concepts. In line with this purpose, 173 students in total of which 57 ones of the 9th grade, 94 ones of the 10th grade and 22 ones of the 11th grade participated in the study in which developmental research method of descriptive research design has been conducted. Four open-ended questions about energy and related concepts have been asked to the students in the study. As a result of the study, it is concluded that the students use energy instead of work, power, repulsion and pulling concepts and they consider energy as a feature specific to living creatures and moving situations. The potential and kinetic energy types are most expressed ones. The students frequently give examples from renewable and non-renewable energy types and they classify them accordingly. It is also concluded that they don't have enough information about conservation of energy. It is thought that this misconception among the students emerges because energy and related concepts are taught them disconnected in different lessons of different disciplines and they do not understand preconceptions about energy and related notions. It is considered that the concept networks, concept maps, and conceptual change texts will help to relate energy concepts in students' minds.