In case of Dethleffs' e.home, the EV is also full of solar cells all over the places (334 square feet / 31 m2). At peak operating times, it should deliver up to 3 kW of additional power.
We couldn't find the exact battery pack capacity, but for the full version (as show here) the German concept is rated at up to 103 miles (165 km).
The non-camper version would get 174 miles (280 km) NEDC, which in real world world end up at around 140 miles (225 km). The electric motor is rated at 80 kW.
The interior seems to be better quality than many homes, so the undisclosed pricing estimate is probably pretty high.