Keep in mind that "full spectrum" is a marketing term, a catchphrase. There's no standardization or regulation surrounding use of the term. About the only thing it consistently means is "costs more".
If you're looking for sunlight equivalency, you need to focus on three more objective criteria - color temperature, color spectrum coverage, and intensity. Full noonday sun on a clear, cloudless day clocks in at about 5700-5800k at an intensity of about 10,000 foot candles and a full IR to UV color spread. You can mimic the color temp easily. You can mimic the spectrum coverage to a degree. Mimicking the intensity is pretty tough without some serious hardware or time under a dedicated lamp.
First, stay away from fluorescent. You can get them in the right color temp and it's relatively inexpensive to build a pretty potent light box with a couple of shop-rated cheapo 4-tube fixtures, but the color spectrum coverage is blech. Tungsten-halogen, no. You can't get an incandescent that will burn hot enough to put out the required color temp, so they're out. That leaves LED. While they are a little more (sometimes a lot more) expensive, you can get them in the right color temperature, the spectrum coverage blows fluorescent out of the water, and the low power consumption means you can stack a lot of them without blowing up your electric bill.
Also keep in mind that 5000-5500k lamps produce an intensely bluish-white light. It washes out colors and makes things look generally blah. Think Cool White fluorescent on steroids. Mimic sunlight it does, but have you ever noticed how wimpy and colorless things look in full sun?
What you might consider is putting in higher output standard socket LED bulbs to max out the ambient lighting, then have a dedicated sunlight-equivalency light box or lamp assembly for use on a daily schedule.
Brad
