France built out a huge number of Nuclear reactors in the 80s. Some 70% of it's electricity comes from Nuclear. Nuclear has a very low marginal cost so when it'

France built out a huge number of Nuclear reactors in the 80s. Some 70% of it's electricity comes from Nuclear. Nuclear has a very low marginal cost so when it's up and running you want to run it at full power as much as possible. At times of low demand in France this means exporting as much of it as they can at whatever rate they can get for it. It's not that they have a huge surplus overall, it's just the economics make it better for them to export rather than load following.