Aim of the dissertation: The aim of the dissertation is to analyse the financial and strategic view of the energy sector in Greece and to interpret the economic impact of the private and state energy investments that take place in the Greek territory in a challenge period such us the decade after 2020. To that end, it investigates the contribution of the energy sector to GDP and unemployment, and it assesses the macroeconomic and microeconomic effects on the growth and extroversion of the Greek economy. Methodology: The dissertation employs secondary data collection and quantitative analysis. The data is collected from reliable sources, including the IEA, Eurostat, EIA. Statista as well as from state platforms such as DAPEEP, Hellenic Competition Commission, Regulatory Authority for Energy etc. The purpose of the methodology is to investigate the public and private investments in energy sectors such as rrenewable energy sources, oil industry & companies at the field of petroleum, Gas & LNG, coal industry, power plants, LNG processing plants, energy constructions, electromobility, energy buildings, pipelines, etc. Further, it will collect information from major Greek companies that engage in energy investments from all the market fields. Structure of the study: Following the introductory part, Chapter 2 presents the energy market in Greece, the energy balance, and the impact of the COVID-19 pandemic on the Greek energy market. It also presents oil and petroleum products, the legislative framework for energy transition and the Target model. Further, it analyses natural gas, renewqable energy sources (RES), energy efficiency and co-production and energy poverty in Greece. The chapter is completed with the presentation and analysis of the National Energy and Climate Plan (NECP) and a thorough reporting of the climate energy targets, the RES targets, the energy efficiency targets, the strategies implemented to address the Energy Union dimensions and the challenges posed ahead. Chapter 3 performs a sector analysis regarding the oil industry companies, natural gas and LNG, coal industry, power plants, LNG processing plants, energy constructions, electromobility, and energy buildings. Chapter 4 investigates e-mobility and electric cars in Greece. Chapter 5 presents energy investments from Greek companies. Chapter 6 analyses the impact of energy investments both on a global and national level and explains the use of RES technologies and the importance of Power Purchase Agreements (PPAs). Also, it presents the next day for energy in Greece. The Dissertation is completed with conclusion and suggestions in Chapter 7.