You don't want a single point of failure. Having multiple lines across a geographic space is the way to go.

It's a big upfront investment, but it could be much cheaper than storage at scale.

I think ultimately you want power transmission stretching from the UK to Japan so as the sun moves the power generation continues.

I imagine it will happen one day, because it would seem to make so much sense, but this is something governments could make happen a lot sooner if they put their mind to it.