It's about limiting power use by attempting to be more "efficient" and cutting down "cooling" costs/energy. When considering indoor grows, this is a "false truth". Energy is never lost, only transformed. How is this relevant, if I have to explain, then that means I'm handing over the goose that lays golden eggs.
You're joking, but nobody is laughing. I am saying this again, no LED light is going to out perform a 1,000w HPS in quality, and certainly not even a fraction of yield. Proof? I can go by LED "suggested use" alone. You can drop the highest intensity LED to within inches of the canopy. Do the same with a 1k HPS and you're "Jiffy Poppin' ". You cannot grow 10' plants (and certainly not 12'), with rocks from top to bottom, under ANY LED/COB. It is as simple as that. Argue otherwise, you're the village idiot. This is fact, not fiction.
Feel free to prove me wrong. Pics don't tell the whole story, but I'll put up a bottom nug pic VS the BEST LED/COB cola. Gauntlet thrown.
The flaw in the LED/COB argument is that the proponents are only considering spectrum/"efficiency", completely neglecting what that "efficiency" sacrifices, which ultimately slows metabolism. To me it's "retarded", but I have a wider "scope", so... . Hint 1, already given above. Hint 2, already insinuated above. HID smashes LED/COB so hard that their mom's butt is sore.
I've seen these grows large scale and honestly they suck ass.
Fact, it is what it is.