Germany has not met its ambition to cover all its power needs for one day exclusively through renewable sources, but half of Monday's demand was met with green energy - 20 out of a total of 40 gigawatts. Consumption was lower because it was a bank holiday and the weather was kind. Most of the clean electricity provided was wind and solar generated. The wind is a problem because it is especially erratic. Germany has this and many other energy challenges to conquer by 2022, when it wants to abandon nuclear power. But work on expanding the grid and adapting it for greater reliance on renewables is going far too slowly. This was the terse message from the head of the German electricity network to Chancellor Angela Merkel, this morning. Her response was: "It is important that renewable energy expansion, its transfer through the networks and the security of the energy supply fit together with financing capability." The price tag on investment in that direction over the coming decade alone is more than 30 billion euros. The aim is to modernise the grid to be able to carry green-produced power to where it is needed, and use less nuclear and coal. Germany is the number one wind power producer in the European Union, followed by Spain. Both are way ahead of the runners-up: Italy, France and the UK. The bloc's member states all have a common goal for 2020, to provide 20 percent of the total energy mix from renewable sources. Each has set its own individual goals. Sweden, Finland, Latvia and Austria are aiming higher and achieving their green ambitions more effectively than Germany for the moment. It has its sights set on 18 percent by the end of this decade. But Germany is already on track to exceed the 20 percent target by then, according to Berlin. Europe's largest economy has become a world leader in renewables thanks to strategic placement of state aid. More about: Ecology, Germany, Solar energy