I already have a grid which handles this situation. I'm lost on what your issue is with the grid?
The biggest issue in germany regarding grid and renewable is a distance of 800km between north germany which has a lot of wind and south germany which has a lot of solar.
The grid which already exists because it was built before solar was interesting.
The grid which connects the Suncor Fort Hills mine in Alberta to Tijuana in Mexico.
Even if you want to expand that grid to the level of everyone getting their winter midnight electricity from the midsummer sun on the opposite side of the planet, the material element of the "electric highway" isn't what stops it, it has a low cost compared to the last-mile stuff that already exists.
