The Norwegian grid is divided up into different regional grids and they each have different electricity prices. Those who build interconnects between the areas can get some of the price difference. It's very different from the UK market, which pretends to have a single area, runs auctions to determine the price and then has to make post-auction adjustments (in the billions) to fix the fact that electricity can't be transmitted across the grid.

See https://app.electricitymaps.com/map/live/fifteen_minutes