**4. Discussion**

This paper has aimed to assess the impact of GDP per capita on penetration of RES and its e ffects in improving real GDP per capita as well. The objective character of the achieved results is ensured by utilization of historical data and applied statistical methods. This work also highlights the importance of producing more energy from RES for the countries to improve their economic growth and standards of living as the increase in the share of renewables provides for increase in standards of living because RES are based on new technologies, create new jobs, boost external benefits for the society, including pollution reduction and

The EU countries were distributed into two large groups basing on the shares of renewable energy in electricity. This research also confirms the necessity to implement important policy measures to promote more active use of RES, taking into account the RES potential available in a country.

One of the main goal in this research has been studying the relationship between the share of renewable energy in electricity and real GDP per capita. Many of the previous research focused on correlation between economic development and energy production or/and consumption. We have chosen GDP per capita since it reflects the achieved level of economic development in the long run and population well-being is a final goal followed by all citizens, and also by governmen<sup>t</sup> [58–62].

One of our important results is revealing the lack of causality between the two variables (the share of renewable energy in electricity and real GDP per capita). This means that production of energy from RES is not so high as to ensure on long-run economic welfare. Other important macroeconomic variables need to be taken into account when assessing the impact of RES on economic growth.

On the other hand, developed countries of the EU do not necessarily have high share of renewable energy in electricity and this is mainly linked to geographical conditions and physical renewable energy potential. There are numerous examples in this regard. Rich countries like Belgium, France, Germany, Ireland, Italy, The Netherlands, Luxembourg, and the UK registered shares of renewable energy in electricity lower than the EU average in 2007 [60]. Except for Germany, these countries also registered lower values than the 2017 European average for the same indicator.

The proposed panel data models suggested that GDP per capita influences the share of renewables in electricity positively and statistically significantly although this impact is very small. A consistent increase in the GDP per capita is necessary to extend the share of renewable energy in electricity [42]. Economic development level of a country has its impact on RES as it allows generating more financial resources to promote renewables as well advanced economies have better developed mature energy markets, better institutional indicators, industrial know-hows, community policies, technological development level, and citizens' openness to business having also positive impact on RES penetration [12,15].

One of the EU strategies is to reduce the final energy consumption and this objective could be achieved following two patterns: improvement of energy e fficiency and growth of the share of renewable energy in final energy consumption and, as an e ffect of this by growing the share of renewable energy in electricity. If this goal is achieved, many benefits are obtained: sustainable development, reduction of global warming, environment protection, reduction of the dependence on energy imports [61].

The enhancement of renewable energy consumption has been observed since 2010 in the EU Member States, as an e ffect of EU Directive given in the year 2009 [62]. Even if most of the EU member states are on an upward trend, the achievement of the 2020 target it not secure, knowing that investments in renewable energy production have slowed down since 2015. Spain and Belgium focused more on the consumption of electricity from RES, the rest of the consumption being based on other types of fuels. Poland made important e fforts to increase renewable energy consumption, but for achieving the 2020 target, has to boost production from RES. Austria, Denmark, Finland, and Sweden are countries where RES plays an important role in the energy mix [63]. In these countries, the lack of fossil fuel resources and the climatic conditions forced society and industry to reduce at minimum the energy consumption.

Even if significant investments were made in the UK for increasing the production capacity of RES, especially for solar panels, this country is far from achieving the EU target. The uncertain context of Brexit creates more barriers. Germany made big progress in the consumption of fossil and nuclear fuels, while France and Italy have serious problems in meeting the targets for 2020 [64–69]. Netherlands also encountered di fficulties because its final energy consumption is based on a natural gas network that is quite cheap; governmen<sup>t</sup> subsidies for the RES promotion are not attractive, being lower than in Scandinavian countries.

Portugal has invested heavily in RES, but high costs did not allow it to maintain a high increase from one year to another. Czech Republic, Romania, and Hungary have a rich network of RES, but the efforts to meet EU target intensified after these countries joined the EU [70,71].

In some EU countries, the target value for 2020 in the case of share of renewable sources in gross final consumption was exceeded: Hungary and Estonia since 2011, Sweden and Bulgaria since 2012, Czech Republic since 2013, and Romania, Lithuania, Italy, and Finland since 2014. By increasing this share, the EU countries will be able to significantly reduce greenhouse gas emissions and improve the environment quality.

This analysis is limited by the fact that only a few variables were considered in the panel data models because of their availability for that specific period and for the EU countries. Moreover, a larger period would have been required for a deeper analysis, however, the data on all the variables in the models are available only since 2007. In the future other important variables will be included in the model and countries will be grouped into clusters according to their geographical conditions and physical RES potential available.
