The article aims to explore the determinants of the process of attracting financial resources for implementing renewable (alternative) energy development projects in Ukraine. The authors review and systematize the sources of funding and innovative financial instruments available for developing renewable energy sources (RES) in developing countries. Based on this, a pool of financial resources/RES development tools available for investment in Ukraine has been formed. It is proposed to build a model of the optimal structure of sources of financing renewable energy development projects. The research is founded on the forecasted schedule for increasing the share of RES in the national energy balance of Ukraine up until 2035. The limitations are connected with the lack of factual data on sources/instruments of funding in the field of RES. The model enables the prediction of the amount of funds that need to be allocated to finance renewable energy development projects, while optimizing the structure of their potential funding. The originality/value of the article lies firstly in the innovative application of the optimization model for forecasting the aggregate structure of funding sources in the energy sector; secondly, in the possibility of testing the model in practice and monitoring RES development projects in the territorial communities of the Carpathian region of Ukraine on the basis of the project-educational center for the development of innovations and investments in the region; thirdly, the proposed model can be used in the activities of state authorities and institutions of Ukraine for forming the policy of supporting alternative energy development projects.