Part of the issue there is that for a large number of people the ‘few times a year’ are major holidays when everybody else wants to tow their house-sized RV and boat to the lake for a day or two. The rental fleet just isn’t big enough to service the surge demand.
FTA:
The so-called plug-in systems involve routing the direct current generated by the panels to an inverter, which converts it to an alternating current. They can then be plugged into a conventional wall socket to feed power to a home.
So, yeah, almost certainly illegal in pretty much any grid-powered home in the US.
The basic problem is that if the grid power goes down the inverter can back-feed the grid enough to electrocute the people who are working to fix it.
Utilities require an approved isolation system of some kind that prevents that happening. They are pretty strict about this for various other technical and political reasons too, but evidently it is mostly a safety concern.
I’ve got some good locations at home for panels, and about 500W in panels that I use for camping, but the equipment I’d need to handle easily and safely consuming the power at home is kind of expensive (just running an inverter and a battery for an isolated system is easy enough, I’ve got all that, but it’s not cheap to seamlessly connect it to my home power system). Would love to have a safe and approved system like what is described in the article.
Can’t forget the boat! For reference, while this isn’t typical, it’s not uncommon. That’s a pretty small travel trailer and boat. I’ve seen this setup with much bigger trailers and boats several times.