Financial Directions for Renewable Energy Sources Investments as a Support for Sustainable Development Policy—Examples of Polish Cities

The EU’s cohesion policy envisages using renewable energy sources (RESs) to realize sustainable development and reduce urban air pollution. In Poland, investments in this area are gradually being made by cities of different sizes, which is the subject of this study. One of the essential tools for implementing this policy is the Regional Operational Programmes (ROPs), under which it is possible to obtain funding for RES investments. Given the high energy needs of cities, such investments are important. A desk research method, qualitative project analysis, and quantitative analysis were used. The authors made inferences based on the data obtained. The authors analyzed all projects financed by the ROPs 2014–2020 implemented since 2014 by Polish cities to use RESs. The beneficiaries selected were local government units. The type and size of RES installations implemented in cities and the relationship between city size and investment characteristics were identified. To date, such research has not been conducted, filling a gap. The results make it possible to determine the directions and scale of financing RES investments in cities of different sizes in Poland, which was considered this study’s primary objective. This study showed that the size of the city determines the type of RES investments. In addition, it showed that the smaller the city, the lower the percentage of projects implemented on their own and the higher the percentage of projects implemented within a cluster or functional area.