Let's say you can get $600/kwH for storage? If you need to cover let's say 18 hrs of energy needs (electricity and heat using electricity) that would give a sense of capital cost for the storage portion of the solar + wind package for germany as a whole? This excludes cost of conversion of course across the rest of things.
This push to dump nuclear and gas for wind / solar is going to come eventually, just not clear we are there yet in available supply / cost etc.
So I don't think its infinite, but extremely high and not overnight.
If you convert natural gas heating to electric (using efficient heat pumps), that adds roughly 9x the energy needs. So $5.4 trillion. And that is just to cover average ‘overnight’, with a little buffer. If there is a problematic couple days during winter? People would freeze to death.
Energy needs would likely be more ‘peaky’ during winter, so these would need to go up a bit to deal with the spikes, but it’s probably order of magnitudeish correct.
The current German population is about 83 million, so that would only be about $65,000 for every man woman and child in Germany for the minimal best case storage needs.
For realistic ‘no mass casualty events due to lack of available heat energy every other year’, it would probably need to be 3-4x higher at least.
To protect against a 100 year storm or the like, 7-10x is probably a better idea. But I doubt anyone would ever pay that.