There are always missing links to these type of perspectives. Off grid is doable but it mostly comes down to demand and that is a function of how the structure was built and how it is used. ‘How it is used’ is mostly a question of lifestyle and what is deemed as acceptable... and that is obviously an issue of individual choice and circumstances. How well insulated is the structure and how well does it accept and reject solar gain? How hot or cold does one consider acceptable? Do you want to cook or do you like to eat food that minimizes cooking? Do you want a fridge or mostly have dried food that doesn’t need much refrigeration? Do you want a hot tub you can jump into at any time... or will a 3 minute shower once ever few days suffice? Are you retired and have plenty of time to tend the place and go chop wood from time to time... or is it a working family with three kids and plenty of demands. The piece makes reference to a place in Spain built in 2014... lots of things have changed since then including the availability of LED lights that take a fraction of the power that incandescent did..... or as part of the lifestyle, have minimal lights and just get up and go down with the sun. And yes, it also comes down to the availability of other resources as befits a particular property..... such as wood that can be used for both heating the space and heating water.
One other thing.... it often comes down to how much of investment one wants to make. Like a lot of things, there’s low hanging fruit but if taken to the nth degree, it gets very expensive and impractical.
Where I live we’ve had exactly 6 days of full sun since June, so there’s that. Oh yeah and right now it’s snowing.