Powerwall.... Do these batteries actually exist? The web page is a little vague about availability, not to mention price. In any event, Powerwalls are unlikely to resolve Germany's grid issues. What's apparent is that the EV enterprise is dependent on the advancement of battery technology. Powerwalls have a stated capacity of 6.4 kWh. (From Tesla's page: Each Powerwall has a 6.4 kWh energy storage capacity, sufficient to power most homes during the evening using electricity generated by solar panels during the day. Multiple batteries may be installed together for homes with greater energy needs.) It appears we're not there yet.