Photovoltaic uses around 1/30th of the land to produce the same energy as with energy crops. 3% of Germany covered would already be a lot. A hectare gets you a

Photovoltaic uses around 1/30th of the land to produce the same energy as with energy crops. 3% of Germany covered would already be a lot. A hectare gets you around 500 MWh/a, so a square kilometer gets you around 50 GWh/a. 3% of Germany is around 10000 square kilometers, so you would get 500 TWh/a, which is around the electricity used in Germany in a year. As a comparison agricultural land is 49%, biofuels are 6.6% of all land in Germany.