The imports and export are changing all the time, depending on the production or demand of each country, to keep the production and consumption in balance. It's

The imports and export are changing all the time, depending on the production or demand of each country, to keep the production and consumption in balance. It's sometimes easier/faster to import power when you need it (when there is a demand spike) than start your own generators to match the demand with internal production. Then when the other country has a demand spike, you pay them back with your production. In many cases no actual money change hands, these are kept as "power debts" that will be paid later. It can also be easier/cheaper to import power for one point near the border than transport it from farther production facilities.