Just this part alone is pretty impressive
I really think ordinary household LED lightbulbs are overlooked. I totally understand people turning their noses up at the concept. It's not sexy. :) But, it's cheap, available and energy efficient.
It's not terribly labor efficient (rigging up sockets, positioning a dozen bulbs). That distribution of light around the plant may make the difference between 20w/sq ft and 30w/sq ft as concentrated top-down light. (But, you pay for that with labor.).
I think they're perfect for the budget grower. Also, the new grower who doesn't want to get too deep into anything before they know they can grow. They can buy 3-4 bulbs at a time as their plant grows. $10 total investment. (Plus the sockets. They're an investment that outlives the bulbs and can be used for sidelighting. They also allow for replacing light at 12 cents per watt.).
They definitely have a place. They're not right or everyone. They're just not as bad as people might think. Far from it. (
Far.).
== Different topic:
There's also a psychological factor, like we were discussing a few hours ago (a few posts higher). When you buy into the latest, most efficient lighting... you're probably going to feel the need to upgrade in a year or two -- as the latest tech reaches the market, and your light fixture has 8 grows on it (10,000 hours of use, maybe 20% lower lumen output).
Lightbulbs seem simpler that way. At 15-cents/watt to buy, you can replace them every grow (I think that would be excessive. I'm just illustrating a point.). And, you don't have the emotional investment which LED users typically have (chasing technology). It's just lightbulbs! Go to Home Depot, see them still on the shelf, and breath a sigh of relief that you haven't been let behind! (wink).
And, really, when you get down to a certain efficieny level, do the incremental improvements matter anymore? A 30% improvement for an HPS grower (going from 50w/sq ft down to 35w/sq ft CMH) is significant. But, when you're at 30w/sq ft, that only takes you down to 21w/sq ft. That's good, but not as substantial. Another 30% improvement is 15w/sq ft.
It's diminishing returns.
I live in a hot environment. I might appreciate 15w/sq ft. But, for most people that's not a thing. (Many, like you?, benefit from the heat of HPS. There's so many factors to what makes a grow light right for an individual.).