Due to the renewable energies nowadays being of a great relevance in the European Union and recent solar energy sector issues in Lithuania and its relevance to investors and the country, the aim of this study is to suggest the ways to improve the solar energy sector of Lithuania in order to increase the attractiveness of investing in it. The ways of improvement are based on existing examples within the European Union. The best features of development models that were proven to be successful in one or several countries of the European Union were adjusted to be eligible for solar energy sector of Lithuania. This book contains an overview of solar energy sectors in the European Union as well as the analysis and comparison of the data. It also presents the suggestions that could be used as a development model to improve the solar energy sector in Lithuania.