This finals thesis strives to assess the cost-effectiveness of investment into solar panel manufacturing in Croatia. Both a theoretical and practical presentation of solar panel manufacturing business is presented in the context of potential investment, in addition to the presentation of the potential of renewable energy sources on the Croatian market. The collected data was used for the preparation of financial statements for the first five years of business activities. The thesis provides evidence of cost-effectiveness of the business idea and it also shows that the return on this investment is expected in around three years and two months. Considering the fact that during the last several years solar cell prices have seen a considerable decrease, the cost-effectiveness of solar panel manufacturing has been recording a continuous increase. This enables more affordable solar panel system prices for all the members of the general public. The data used in this research study was collected from throughout different websites, scientific papers, books and financial statements provided by similar companies in order to provide as realistic analysis results as possible. Against the backdrop of the final figures of this analysis, project implementation is recommended.