Although Germany has massively invested into green energy, the issue is that the electric network has not been sufficiently expanded. This means that solar and wind energy has to be turned off to not overload the network. However, the owners of solar/wind energy still get paid. This means that in Germany, the price of energy will only make up ~50% of the bill. The other 50% are payments for unused energy (to not overload the network) and costs for expanding the electric network (because some regions such as Bavaria refuse to have wind turbines or solar panels “because they look ugly”, but still need electric). Lesson: When implementing renewable energy in the rest of the world, we have to keep in mind that we have to massively invest into the electric network as well or it won’t work.
The problem is that you need a reason to transport the electricity from Spain to Germany. There are very real limits to the electricity grid and that means, that you can not ignore the location of the electricity production. So in a market based system, electricity in Spain has to be cheaper then in Germany, the difference being the cost of electricity transport and/or the cost of flexible electricity generation in Germany, depending on the grid having enough capacity.
That does not mean barriers, just a system to not pretend the weather in Spain and Germany is the same at all times or that the electricity grid is not limited in any way.