I will try to maintain both threads as best as I can... (01/11/2010)
So I was thinking about getting rid of my ugly array of CFL lights and using ONE small HID light for better penetration. I currently have 188Watts of CFL light, which ammounts to 12000 Lumens. I was going to switch to a 150W HPS... I figured I'd get less lumens but better penetration. I did a BUNCH of research and thinking, and changed my mind... I'm sharing it here now to save others time and confusion so I hope this helps somebody... Also I'm definitely not a genius so if I've calculated way wrong please feel free to call me out on this...
Like I said, I've currently got 188watts of CFL dispensing 12,000 Lumens, which comes out to 61 lumens/watt if you count 10watts worth of pc fans to keep them cool. My area is about 4square feet, so at 3,000Lumens per square foot, this is a good place to be in.
According to specs, the 150Watt HPS bulb delivers 15,000 Lumens of light. At face value you'd think that means it's efficiency is about 100Lumens/Watt, but us stoners are smarter than that right? What they won't tell you is that the 150Watts is the power being drawn by the bulb. There is an electrical loss (as you'd expect) inside the ballast which is reflected in the form of additional current drop. (inductors and capacitors present "reactance" [ac resistance], blah blah blah, been too long since I went to school for some of this...)
Anyway, if you read the spec sheet for the 150 watt ballast (based on info from 1000bulbs.com) it will tell you that the operating current of the ballast (NOT the open or starting current) is 1.65 amps at 120V AC... If you plug this into a units converter, it will tell you that the actual power being used by the lamp is 199Watts while it is on. This brings you down from the 100lumens/watt efficiency you thought you had to an actual efficiency figure of 76 Lumens per watt ACTUAL efficiency.
Although 76 Lumens per watt is better than the 61Lumens I'm seeing now, that's only 15lumens per watt more than I'm getting now. Let's make the comparison for the sake of example in terms of real power usage veses output:
199 Watts of power used (on a 150w HPS) yields 15,000 Lumens
208 Watts of CFL used (26W bulbs times 8 Is the closest you'll get) Yields 13,600 Lumens (1,700 Lumens per bulb)
Do the subtraction and for the same ammount of power used, the 150W HPS Lamp is only ahead by 1,400 Lumens. That's LESS THAN ONE EXTRA CFL BULB!
So how much bigger do you have to make the HPS lamp before it starts kicking CFL's ass in terms of power efficiency? Below you will find I have done the math for the popular sizes of High Pressure Sodium bulbs:
70w(90Watts actual)- 6000Lumen 67Lumen/Watt
100w(124Watts actual)- 9500Lumen 76Lumen/Watt
150w(199Watts actual)- 15000Lumen 76Lumen/Watt
250w(300Watts actual)- 29000Lumen 97Lumen/Watt
400w(468Watts actual)- 50000Lumen 107Lumen/Watt
600w(660Watts actual)- 90000Lumen 136Lumen/Watt
1000w(1140Watts actual)- 140000Lumen 140Lumen/Watt
As you can see, the efficiency doesn't start to get worthwhile until you get up into the 250W-400W+ range. So I guess you could argue that CFL is the obvious choice for someone who wants to stay under 250 watts...
So, are you bummed out because you think $60-$100 bucks for one of those huge 150watt cfl lights is unfair? So do I. The GOOD news is that in terms of light output per watt, the smaller CFL bulbs are more efficient than their larger counterparts. See the enclosed data below
26W- 1700Lumen 65Lumen/Watt
42W- 2600Lumen 62Lumen/Watt
65W- 3400Lumen 52Lumen/Watt
85W- 4200Lumen 49Lumen/Watt
105W- 6900Lumen 66Lumen/Watt
150W- 8200Lumen 55Lumen/Watt
200W- 10000Lumen 50Lumen/Watt
Although it's not a huge difference, you can see that CFL bulbs show a general trend of decreased efficiency as they grow larger in size. What this means to us CFL nuts out there is that for about 25 bucks you can get a couple 3-packs of 26 watt CFLs (2700k of course). You'll use 156Watts and pump out 10,200 Lumens. That's 2,000 Lumens more than you get with that expensive big 150W bulb. Not to mention you can replace the bulbs individually if they burn out (for cheap), and did I mention that they run pretty cool? The 150W monster CFL runs WARM-hot...
Now granted you'll have to rig up your own reflector hood or whatever, but stop and think about this for a second- the grow sights want an extra $65-$100 bucks for the reflector/wing thing for those huge 150Watt cfl bulbs anyway. For half that or less you can rig up your own with a bathroom vanity fixture and some Y-splitters, or some of those jobsite clamp lamp things with the aluminum reflector dome built in.
So that's it... If you've made it to the end of this post then I thank you for your time. Basically the moral here is don't bother with small HID lights... If you're going to stay under 250Watts then just do CFL, and don't you dare waste your money on one of those huge 150Watt CFLs- get a bunch of smaller bulbs for cheaper, with better heat control, more lumens/watt, and more versatility for distributing your light.
Edited by CFLweasel, 12 January 2010 - 01:50 AM.