I saw a single person standup foil on a local lake. They look unreal, almost unbelievable in operation. Like someone is flying over the lake. Search for efoils on youtube

This does sound approachable. From my experience, people with lake front property and docks with boat "houses" are clear from any obstruction of direct sun. Line the roof of said boat "house" with solar, and in the typical weekender/vacationer use of a boat, seems pretty managable. However, when the sun is up to be charging is typically the time of the boat's use so it won't be on the charger. Use the solar to charge a powerwall type of solution, and then charge the boat at night?

Solar panels could be on the boat itself, but I am assuming solar won't be able to do much recharging while the engine is in use anyway. OTOH, very few boats are used, or moved, every day.

I imagine a boat would have a hefty battery pack anyway, to power a stove, fridge, air conditioning, plus essential bridge equipment.

I think we're talking different sized boat on a lake. Do house boats typically power from battery or from a generator? I have no familiarity with those.

Most houseboats are barges with no propulsion. They use shore power but often have a backup generator. Having some solar or a small wind turbine is relatively common too.

Yes. I was thinking "river boat with limited propulsion that is moved when the owner wants a change of scenery".

Boat houses are extremely heavy, for obvious reasons. Hydrofoil requires light construction, so these two are not compatible (plus it only works at speeds you would not want to have a house moving at).