Good discussion here. Lumens are fine for comparing bulbs but only if they share the same exact spectrum (they rarely do). There are a few misconceptions I have been trying to sort out about efficiency and spectrum. First thing to recognize is that 600w and 1000W HPS are much more efficient than the smaller sizes (70w HPS is 85 lumens/watt). So let's focus on them when we talk about HID. A 600w HPS can produce 150 lumens/watt and their radiometric efficiency is about 40%, which is mega! Currently on the market is the Cree XP-G R5 bin, which can emit 132 lumens/watt with a radiometric efficiency of 40-45%. Cree plans to release a new LED this fall the XM offering 160 lumens/watt at about 50-55% radiometric efficiency. So yes it is true that LEDs can be more efficient at emitting photons than the best HPS can ever hope to be. However, the commercial LED lamps currently on the market do not use Cree XP-G R5 bin, not even close. More likely the best lamps are using LEDs of 15-25% radiometric efficiency, similar to the best fluorescents. Even worse, there are no deep red (660nm) LEDs on the market that I am aware of that offer better than 20% radiometric efficiency.
As far as spectrum goes a common misconception is that plants do not use green photons for photosynthesis. Yes it is true that plants reflect green preferentially but in practice green photons can drive photosynthesis. A perfectly tuned spectrum is not the magic bullet us LED guys were hoping for. However a significant increase in efficiency over HPS spectrum can be had with LED ~20% increase. The rest of the gains LED can offer over HPS comes from more even spreading of the light and more accurately directing the light to the canopy. HPS fires photons is all directions so unless it is used vertically, many photons are absorbed by the reflectors. LED on the other hand offers a more directional output. Reflectors and lenses can tighten the beam but they also absorb significant photons in the process. So if we buld an LED lamp using LEDs with a correctly tuned spectrum, properly cooled and using 40-45% radiometric efficiency LEDs we should be able to defeat the big HPS lamps in efficiency by a factor of about 2 (using half or less the watts to get the same results). That results in 1/2 the heat as well so there may be savings from cooling fans and AC systems which add up fast.
In general use, LEDs look even better. Consider that you've chosen the MOST efficient wattage of HPS for comparison. 150W of HPS would get its ass kicked around the block by 150W of LED. edit: and I just read about cree finishing/demonstrating a 200lum/W white LED. Not to mention that white doesn't get overrated by lumens in the same way that very yellow light from a HPS does.
Damn feels like science class all over again, except I didn't sleep through this thread. I only understood 10% of the conversation but good read none the less.
when the growers that I respect the most switch to leds I will reconciter it. but with the crap on the market and the ureliability in the real world you will have to do alot more than recite out of some book that says this is the way it should be. You show me the grows. Oh and by the way (Quote) " LEDs produce MUCH more output energy per unit of input energy" that my friend is against the laws of phyiscs. They state simply " energy cannot be created or destroyed, only transfered. if led light created more energy than was put into them, they would end the energy shortage. and to think France has spent billions on a colider to do just the same thing....
I think what he meant to say was LEDs are more efficient at converting a Watt into Lumens. Less energy is transformed into heat than HIDs, systematically lowering overall wattage used for climate control, a peripheral bonus. each watthour is converted into more lumens in the correct wavelength, and if placed close (possible due to lower operating temperature) more lumens per watt are absorbed by the plant. This is but one facet of the issue. Watt Efficiency. It does not cover canopy penetration, overall lumen output, or a number of other factors needed to consider the debate. -- You down with LHC? Yeah, you know me.
I just see it as more disinformation from the led set. in the real world 95 % of thier claims have proven to be just plain lies. i hear about all these great led grows....show me.
[ame=http://www.youtube.com/watch?v=zNfm7XSxVPs&feature=related]YouTube - 600watt-LED Cannabis Grow, 540grams dry weed[/ame] That's pretty close to the 1g/w goal of many. Extremism rarely merits truth.
3000 bucks in lights, 540g divided by 24 plants = 22.5 grams per plant. , less than 1 ounce per plant. I can do better than that with a 250 hps. , I average between 2 and 4 ounces per plant, dried. and if i went back to outdoor i could easily double that. i would look for between 8 and 10 pounds from 24 plants. half pound plants are not uncommon in an outdoor grow. to see a yeild like that from a setup that expensive, i would conciter it a dissapointment. definately not convinced. show me a back to back grow , hps vs led, equil wattage, starting with cuttings from the same mother. the hps will still outpreform the led. even the led did win the yeild would need to at least double the hps to justify the added cost.
Pride. Not logic. That's not 24 plants, so the math is off. Measuring weight per plant is unsound considering the difference in growth patterns of different strains and even phenotypes, as well as growing methods such as ScroG and SOG, trellising, serpentine, lolipopping, etc. Each method and strain will affect yield. Outdoor is completely irrelevant to the thread (pride again, dude chill, you're cool). And you aren't figuring in upkeep costs or operating costs, or peripheral costs of heat + space management as well as initial setup requirements such as wiring and mounting, physical footprint and transportable advantages, only initial investment... There's a few. type in w-w-w dot g-o-o-g-l-e dot c-o-m. It's a really neat tool for finding things on the internet, show-me boy. And you can not figure added cost of initial investment. Anyone growing more than once can make up the savings of running a higher wattage system that requires biannual upkeep and higher operating costs. -- Damn yous guys is some snippity stoners. Smoke a bowl. Both options are viable and have both advantages and disadvantages. There's black and there's White, but there's also PAR and Lux...don't forget all the colors of the debate. "Best" is bullshit. Hyperbolic tendencies NEVER solve ANYTHING, ANYWHERE, EVER! -- PS spellcheck, bexuz erros maek yuo look stopid.
For the open minded and LED enthusiests/pioneers... http://webench.national.com/webench5 This progam, from National Superconductors, is a most excellent option if you're building your own lighting system. It features a comparative chart of LEDs and even helps you design the circuit and produces a bill or materials for parts. Signup is free. -- Now I'm gonna bitch for a second about LEDs available now. My main problem with the LED boxes that are available now is the obvious shortfall in design, centralizing the LEDs on a single board in a similar fashion to HIDs. Apparently most LED designers want to mimic product functionality of HIDs, creating a central light source on a single board. But with LEDs, the potential to disburse the light source in a 360deg. radius of the growing area, as well as the ability to place the lights near in contact with the plants should take rise to new designs. LED walls on every side, under-canopy LED sheets that fit around the base of the plant, independent or cluster light boards allowing for easy conformity to canopy height and shape, inner-canopy light "orbs" dropped into the canopy. All of these have the potential to do what HIDs can not. LEDs may not have all the power of the HIDs but they have the potential to be something more. The LED guys aren't thinking outside the box, literally.
they do make small 45w led pannels. they could easily be arranged in multiples anywhere in your cabinet. I want to believe in leds. they do veg extremely well. but 3 months out of a light. a dealer who wont stand behind the products they sell and as far as that went neither would the manufacturer. i want stuff i can rely on. the 400 bucks the led cost me was difficult to loose. i am on a fixed income and i just dont have that kind of cash to throw in the garbage. on top of that it cost me another 400 to replace it. it came to within a knats ass of weather i could continue with my program. i would love to replace the 200w cfl in my vegging cabinet with about 200w of led lighting. after my first go round.. i just cant trust it wont be another huge waste of money.
Yeah man, you had a bad buying experience. Was probably filled with cheap chinese components assembled by a 5 year old, or worse, a stoner working at the store. The market options for LEDs are limited and lacking, but the DIY community has the potential to revolutionize micro grows in a few years, and larger grows within a decade. As tech prices (hopefully) drop, the initial investment will recede and the output potential and thermal efficiency and footprint will make LEDs more viable to low scale growers. I was talking with some local dispensary in-house growers this week, they've decided to go LED to save on both operating watts and climate control watts as well as bulb replacement costs over time. At a production level like that, the initial investment is recovered quick enough to justify it. Home grows are a different story, but even there, the compactness and low heat are big bonuses. It seems to me, if they were cheap enough (and better quality than the one's you bought, Mr. Bob) they could win the debate. The price seems to be the ultimate limiting factor, as without the exubrent price tag, we could just line every wall of the room with thousands of LEDs, and drop clusters into the canopy. You could get real tricky and create a current 'throb' that encircled the room, ebbing the lights across the room to create a sort of "light spinner." Plants would constantly be trying to turn towards a different section of the room, top to bottom and ever changing, leading to thicker pedunkles that can carry more nutrients to the developing calyxes and wider lateral canopies with thicker underbrush. Damn, that'd be one psychadellic grow op....I'm on it, see you guys in 3 years with pics.
GrapeStreet: I agree with what you are saying completely with one adder. The reliability has got to improve. 3 months just wont cut it. Led still needs time. As I have said before, when the growers I respect the most switch to led , I will reconciter. Right now, its a universal Leds Dont Work.
Wow. I forgot about this thread. I actually let you get away with posting this garbage in this thread for a while. You're a moron, and a petulant moron. The worst kind. [Name calling is not allowed here at the city. -FW] No lighting technology is perfectly efficient. HID lights are like 40% efficient AT BEST. That means there's a 60% gap in efficiency that can be exploited by more efficient lighting technologies to be better than HID. Thanks for being stupid and erroneously trying to apply laws you don't understand, though.
Bullshit, bullshit, bullshit. You can't say anything true. A 250W HPS will not give you 1g/w, EVER. And outdoor? What the fuck is wrong with you? You're comparing OUTDOOR grows to LEDs to try and demonstrate that HID is better than LED? Seriously, you have no logic skills whatsoever. Also LED will win your stupid comparison. They produce better g/w than HID. They're more expensive watt per watt, but don't fucking try to act like that's what you meant in the first place. When you got called on your stupid bullshit you decided to change your argument to one of expense? Awful. Don't post in this thread again or I will rip you a new one. [Disrespect doesn't fly either. -FW]
Also base reliability for LEDs is nowhere near 3 months. You're buying some cheap ass indonesian garbage if it's only lasting that long. "Penetration" and other myth factors that people try to use when comparing lights is pointless. More light=more penetration. End of story. The only way to achieve greater penetration with the same light is to throw its light across a smaller area. Therefore, efficiency at converting input to output energy IS already taking penetration into account. The only factors that matter are light thrown and the spectrum of that light.
my math says 4 ounces is 112 grams. that is 1/2g/w, at 2 ounces 1/4g/w . Those yeilds are very possible with a 250 hps.
600W making nearly 600g = roughly 1g/w. This shit isn't that hard. Pull some more numbers out of your ass why don't you. 250g = 8.8oz. You pull off 8.8oz out of a 250W hps and there's a place in every marijuana publication on earth for you.