Reaching a neutral use of energy in the building environment is challenging. That is because, as the population expands, so does the energy consumption. Considering that the building environment is accountable for 40 percent of energy consumption and 36 percent of total CO2 emissions, the building sector has to conform with specific guidelines and targets, in order to reach neutral energy use. Newly constructed buildings are already targeting better energy performance. However, more than one fifth of European building stock has been built before 1945, and together with low renovation rate in Europe, heritage buildings are struggling to become part of the new energy reality. In order to complete the energy transition, every sector of building environment should commit on energy saving and producing interventions. On one hand, by renovating heritage building stock energy is saved and buildings are performing better. On the other hand, it is challenging to apply energy production interventions in such buildings in order to balance the energy demand. This is the reason why, the current research is focusing on how photovoltaic technology could be applied on heritage buildings, without compromising their architectural character. The application guidelines, which are going to answer the latter question, are going to be tested on a heritage case study in Greece. Moreover, the legislative framework for energy transition is going to be described with the purpose to explore the extension of the guidelines, since they are covering all sectors of human activity. Additionally, the building stock in Greece is being presented and how the European legislative framework is applied in this country’s concept. What is more, photovoltaic technology is going to researched in depth, specifically how the photovoltaic cells are producing and how do they produce energy. In order to get more explicit about solar interventions on heritage cases, such as where is the best place for the application and why. In addition to that, more criteria for suitable solar application on heritage are going to be researched, such as color, transparency, size and functionality. After the literature research on both heritage culture and photovoltaic technology, and also the applied version of them in reference buildings, a list of design requirements has formed. Therefore, the only way to test if these guidelines could be used for photovoltaic application in a random building, then it could be very valuable to similar future interventions. Thus, a heritage case building in Greece, specifically in the city of Florina of north-western Macedonia. Regarding the design process, up next, the photovoltaic application is going to be analyzed based on the design requirements of the technology upon heritage and the specific demands of the building case. Supplementary to design guidelines, a matrix is formed in order to present all the different options for the interventions. By the end of the matrix, two energy scenarios are forming in order to perform the application in situations as close to reality as possible. Regarding the design, public opinion upon energy interventions is very valuable, and especially when it comes to solar application on heritage buildings. Moreover, the acceptance of similar interventions is going to be discussed. In addition, and in order to have specific overview about public acceptance in the local community of this research case study, a questionnaire is going to be conducted. The results are going to be presented and the public’s influence is going to be examined. Ultimately, the final design proposal for the case study is going to be demonstrated and the different applications are going to be analyzed. Finally, an overview of the design proposal is being inspected, as far as it concerns the building itself and the urban environment in total. To sum up, general conclusions re going to be presented and also the limitations of the research itself. A few suggestions are additionally to be explored for investigation of future possibilities on the subject.