Fluorescent lights definitely do emit in the wavelength that harms hopped beer. They don't have anywhere near the potency of the sun, but it's worth putting a t-shirt over the carboys IMO. Winers (er, ah, "winemakers") do say to keep wine in the dark, but I'm not familiar with the exact reactions they're concerned about. With beer, it's the isomerized (bittering) hop resins which further isomerize into mercaptans which taste and smell like skunk. For a sensory training exercise, try a Heiniken in the green bottle anywhere in the U.S. That skunky aspect ISN'T supposed to be there! Green glass doesn't filter out the harmful wavelenghts of light, only brown will. This defect is so pervasive, and Heiniken is so popular, that these mercaptans have become associated in American consumer taste panels with an "imported" flavor that is not recognized as a flaw. For laughs, get a twelver of Heinie bottles in the cardboard case. Set two on a bright sunny windowledge for a few days and compare.
Even better, start with fresh homebrew that hasn't been mailed across the ocean and abused for weeks. Bottle a six-pack in Corona bottles. Set two out every two days in the sun (so you have six-day, four-day and two-day struck bottles) and do a triangle test including non-lightstruck bottles. You'll be blown away. People with trained and sensitive evaluation skills can detect it evolving over the course of each pint on a sunny patio here in CO where the sun at altitude can feel like a microwave.
So I guess for my money, even for wine (I don't know why but it's good general practice), put a t-shirt over the carboy or a brown paper grocery bag with a hole for the airlock.
Bees, brews and fun
in Lyons, CO