Home evolution is definitely a great sector for Apple. Connecting devices to home appliances is very simple and creating a product that is cosmetically neutral and appealing is Apple’s strongpoint.
Recycling energy takes energy, that’s why it is such a difficult field. However with light sensitive tech,it is possible to create a household appliance that can go into a low-power mode when the appliance would produce diminishing returns.
I can already see a house with grey walls and pearl-white apple appliances that connect to your AC Oven and Dryer and any other home energy consumers.