This thing is awesome. A travel trailer (or caravan if you're from Europe), the Dethleffs e.home coco features an 80 kWh battery in its base that feeds a powerful motor for each wheel, allowing it to increase the ease with which the tow vehicle functions. In the offseason, it sits beside your home, generating a small amount of electricity from its roof, but more importantly, serving as a battery backup, or perhaps a daily buffer: feed your home from the battery when electricity is expensive, then charge it back up when it's more expensive (typically at night). This would help it pay back some of its (probable) substantial cost.