I'm Dreaming of a Green Xmas...
Somehow I doubt the power is "transported" directly to the Champs Elysee. I am guessing it is just a piece of arithmetic between what the Pyrenees installation pumps into the local grid (consumed by Toulouse, Perpignan etc) and what the lighting takes out up in Paris. And the same trick means no need for storage (just averaging over 24 hours). The reality is those Parisian electrons are coming from a nearby nuclear power station.
Pity, because it would be so much more impressive if local solar-PV on the roofs of that very expensive real estate was powering the lights. Trouble is, at this time of year there are more and more grey days, so the lights would not be shining so bright.
But, it's a start.