When I say "most of the primary energy requirements are satisfied above" I mean averaged over a year, where a square meter of solar panel produces about 150Wp and has a capacity factor of 11%, i.e. a square meter of solar panel produces around 130kWh/a. 2.4 million hectares would produce around 3200TWh per year, Germany consumes around 4000 TWh per year. These are of course just rough ballpark estimates.

You probably want to diversify into wind too to reduce storage requirements. IIRC wind also produces a bit more power per square meter in Germany than solar. Right now there isn't enough storage to cover the windstill nights, but there are no technical reasons why we can't store the power either in batteries, as Hydrogen or Methane, as heat, or, where geography permits, in pumped hydro (or a combination of different storage technology). It's just a bit expensive right now.

I am tired of this. There will be a lot of batteries once we get EVs. No, you do not need to charge a grid battery to charge your EV, can people please stop with this joke.

The other factor is that grid storage isn't profitable because there is almost zero demand for it. Please wait until it becomes a problem.

A corn monoculture is not a valuable biome. Otoh, a pesticide free meadow under a PV array that is "mown" by a couple of sheep can be a valuable biome.