Do some research BigBlock.

LEDs have an extremely lightweight and compact design. This fact along with low heat emissions make LED's a very attractive light source. Also, they can be designed to emit the specific wavelengths required for photosynthesis (fluorescents and HIDs emit alot of wasted light).

BigBlock is right that LEDs are not cost efficient (yet), but there is a great deal of research and development in low cost production.

If you have problems with space and/or heat, and you have the money to drop, LED's might be for you.
smoknjoe Reviewed by smoknjoe on . About those LED lights I was reading that in order to equal one decent HID light, you need a panel of like 52 LED grow bars. One LED grow bar goes for $150, so that's $7800 vs like $300 for the HID. You do get greater bulb life, but 52 led bars, with three light clusters per bar, is going to take up quite a lot of space, so there's absolutely no real advantage. So don't waste your money on LEDs. Rating: 5