Renewable energy costs vary across Europe due to different weather conditions. Cooperation between countries in building renewable energy sources can lead to significant efficiency gains. If European countries continue with individual approaches after 2020, the cost of the electricity system could increase by 5-7%. However, if they work together to meet renewable energy targets, the additional costs would be 41-45% lower. This shows that cooperation is more cost-effective than individual efforts. To make the most of these benefits, administrative barriers need to be removed, and fair cost-sharing among countries must be addressed.