I just wanted to provide a place to discuss LED Lighting, primarily the differences between diodes (Lights with a purple hue) and full spectrum COB's (Appear to be "White" light).
Here is a list of definitions of all the primary Lighting terms:
LEDs are very complicated when it comes to calculating the actual amount of light usable to a plant. From a DIY point of view I can't imagine trying to build my own LED fixture using 50 diodes. A single COB bulb makes it very easy to build, this one light got me started growing for $40. and with 5 you can easily illuminate a 4x4' area for $200.
I will say there is a newer CXB3590 Bulb by CREE now tops out at 300 lumens per watt, which is very impressive given where they were ten years ago:
Here is the CREE CXB3070 COB LED installed onto a heatsink:
I find that CPU coolers are extremely cheap to find because there are so many on old computers, they tend to be more than sufficient to cool the bulb (100-200W active heatsink). I can say that the lights are capable of growing 4" California Sweet Peppers which require a full spectrum, as well as high intensity lighting to actually create large peppers. They operate at 36V and are capable of 100W, but to get them to be more efficient I only drive them at about 1.4 Mamp. This allows me to have it run at almost 66% efficiency in terms of output.
LED Driver: http://www.mouser.com/Search/ProductDetail.aspx?R=LPC-60-1400virtualkey63430000virtualkey709-LPC60-14001
If you all are interested in learning more about plant lighting requirements, I highly suggesting reading this article:
If you all are interested in learning more about LED lighting calculations, this article is very comprehensive: