I just finished a shelf for starting seedlings indoors. It's got room for a heating mat at the bottom. Three shelves above that have six T8 flourescent tubes each. I used lumber yard spruce so it's light weight and the bolted construction means I can disassemble it.
The lights are adjustable in height and are plugged into switched receptacles controlled by a timer. A second timer controls a switched receptacle for a fan. A GFI receptacle provides downstream protection for all the wiring.
With the lights raised up there's about 18" of useable height in each shelf space.
If that's not enough for taller plants a light section can be removed, a shelf removed, and the available height doubled.
Rope and friction hitches are used for light adjustment and removal.
Spring is coming!