Fluorescent Christmas lights did exist at one time. Not sure when but they did exist. I have a strand of them. Uses 13 watt PL bulbs. But only 5 bulbs. They didn't really take off like LED and incandescent did. And, 13 watts times 5 bulbs versus 7 watts times 25 bulbs...that's probably the reason why. Now, if they had used neon bulbs that screwed into incandescent sockets that only used say 3 watts, maybe. But 13 watt Christmas bulbs and only 5 bulbs? Yeah right! Especially with today's Christmas lights.