I don’t get it. Is that an American thing that your power is generated by a different resource depending on the time of day?!
I don’t think that’s the case here. You get whatever source you signed the contract with here as far as I know.
Also how would the phone KNOW.
So let me get this straight. You're saying that you can sign up for solar generation, but once the sun goes down your electricity goes away because that's the only source you signed up for? Or are you saying that you are served by a single power plant, and if it needs maintenance then you lose electricity for however long that maintenance takes (potentially weeks)?
Using multiple power generation sources, yes each potentially using a different method of generating that power, has been part of power grids for GENERATIONS now. And no, this is not just a thing in the US. Why do you think Germany is considering delaying/scrapping their plans to retire multiple nuclear power plants with the Ukraine war going on and Russia cutting off their natural gas supply? It's because they use multiple methods of generating electricity, despite having some of the highest adoption of renewable energy in the world.
Source: My father was plant manager for multiple power plants while I was growing up. These included coal, natural gas, and hydro power. And ALL of these power plants served a single mid-sized city in the western US.
Edit to add: Or perhaps you meant that your power grid only uses a single resource for its entire power generation. That must be one small grid. Either that or you're claiming that every single power plant in a place such as Europe all use the exact same resource for their electrical generation, since every power generation source in Europe is connected to the
synchronous grid of Continental Europe.