**5. Conclusions**

The panel data models indicated a positive, but very low impact of GDP per capita on the share of RES in electricity in the period of 2007–2017 in the case of the EU countries. However, causality between the two variables was not identified.

The EU member states were grouped by means of cluster analysis, however, future research would be necessary to ge<sup>t</sup> more robust results and develop specific policy recommendations. The extension of this model is required by including other important variables such as RES potential available in the countries based on geographical conditions and other important factors which were not addressed in this study.

Economic development level of countries is supposed to have significant impact on the exploration of RES potential taking into account geographical conditions of the countries in question. Higher economic development level first of all allows raising more funds for renewable energy support. As the old EU member states have also more developed energy markets, stronger institutions and legal frameworks, lower corruption perception levels, these issues need to be further explored.

Some other aspects need deeper analysis as well, namely, the political, social, economic, environmental, and technological determinants behind weaknesses and strengths of renewable resources. It is also important to assess the e ffects on RES expansion of the following specific factors: policies promoting RES, investments in the field of research and development, internal energy production, industrial know-hows, community policies, energy dependency, technological development level, and citizens' openness to business, institutional indicators such as corruption perception, regulation quality etc.

RES as such is supposed to have a positive impact on economic growth as it provides new jobs, technological innovations and also promotes GDP growth. Therefore, it is important to analyse the impact of RES deployment level on economic, social and environmental indicators of the countries, however, additional variables need to be integrated into the model as also having impact on GDP per capita growth rate.

**Author Contributions:** Conceptualization, M.S. and D.S.; Methodology, M.S., D.S., Y.B., E.K. and S.G.; Formal Analysis, M.S., Y.B. and E.K.; Investigation, Y.B., S.G. and D.S.; Resources, Y.B., E.K. and S.G.; Data Curation, M.S.; Writing—Original Draft Preparation, M.S., D.S. and S.G.; Writing—Review & Editing, M.S. and D.S.; Visualization, M.S.; Supervision, D.S., Y.B. and E.K.; Funding Acquisition, Y.B., E.K. and S.G.

**Funding:** This research received no external funding.

**Conflicts of Interest:** The authors declare no conflict of interest.
