The goal of this thesis is to examine the issue of energy transition and to highlight the importance of photovoltaic systems in the attempt of Greece to decarbonize its economy. Additionally, the author examines the role of this technology in the country’s energy security, society and energy system in general. During this process, there are mentioned the challenges that are derived from the need for further deployment of PV systems. Furthermore, the thesis investigates the opportunities that are appearing for Greece through embracing energy transition. These opportunities include the conversion of Greece to an energy hub or energy export country through the tool of international grid interconnections. Finally, a comparison between Italy and Greece in terms of energy transition is attempted. The present thesis concludes that energy transition is a necessity in a global level. Faced with this reality, Greece has to start producing energy exclusively from clean technologies. Photovoltaic systems can play a crucial role in the attempts of Greece and can provide the country with multiple benefits.