I've searched through some LED topics but havent found mentioned anywhere:
How many Lumens would a mature plant need if LED's were used?
How many Lumens would a mature plant need if LED's were used?
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LED - Lumens/sq. ft.?
- Thread starter llbuckshotll
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From what I know you dont go led for lumens. You go led for spectrum coverage and you want about 200+ watts and potentially two panels. Theres a chap on here just made a thread. Hes got nearly 400 bux worth of led setup. It is significantly more expensive than the other options. You can get second hand metao halides and hps for under 100.
Sarge said:
Is this by chance me?
You are right about lumens not being important (though these lights are way too bright to look at directly, I will even use sunglasses occasionally if I am working on the plants while they are under the light, the indirect light reflecting off the leaves, pots, table etc are blinding.) you are really interested in photsynthetically active radiation or PAR http://en.wikipedia.org/wiki/Photosynthetically_active_radiation . It is a measure of the amount of light that is useful to plants.
For example, say plants only need red light (a majority of their absorption is actually in the red spectrum), so you get a red light with 1000w. That means 100% (minus losses for heat) of the energy is going toward growing your plant. However, red light is the "dimmest" light (not including infra-red or UV etc) so even if you are putting out 1000w of growing light, you may have low lumens.
Now say that the light is a "full spectrum" light such as a HPS, halogen, or fluorescent light. Even if you ignore all the losses, efficiencies etc. these lights are putting out light in spectrums your plants cannot use, or do not absorb, such as green, orange, yellow etc light. This is wasted energy.
However, this wasted energy can be bright. Lumens is a measure of brightness, so if you are putting out 1 million lumens of green light, you might have one bright ass light, but you aren't doing any favors for your plant.
Here is a good chart of the absorption spectra http://hyperphysics.phy-astr.gsu.edu/hbase/biology/imgbio/chlab.gif
The great thing about LEDs is that they can target specific wavelengths of light so you don't waste energy putting out light you don't need. So even if a 300w LED panel isn't as "bright" as an HPS etc, it may be more effective because it does not put out heat (LOTS of energy wasted, not to mention you must place the light far from the plant) and it does not use energy to produce light your plants can't use.
Hope I am making sense, I'm rambling, I can already tell.
A 250w led will produce the same heat as a 250w HID, or 250W incandescent, or a 250w heater.
It's because the light converts back to heat.
It's because the light converts back to heat.
NateFrentz said:
No it won't. Heat is wasted energy for lights. The amount of heat it puts off will vary based on the efficiency of the light source.
They all will use 250 watts; that is true.
This is roughly the order for efficiency. Top of the list=most efficient.
HPS
MH
LED
T5
T8
T12
Incandescent.
NateFrentz said:
Incorrect on so many levels.
Jeff H said:
More correct, but still incorrect. This "efficiency" is based on Lumens/watt. As I mentioned earlier, lumens are not a good measure of how "good" a grow light is. Also I am not convinced that HPS and MH are more efficient than LED. I never see 1000w LED grow lights for sale but I commonly see 1000w HPS or MH grow lights. Also, cities are beginning to change their HID street lights to LED to save money.
Typically the cooler your bulb is, the more efficient it is. And we know both LEDs and Fluorescents are cool to the touch. However, fluorescents suffer from the same problems as other full spectrum lights
EDIT: Also, I just wanted to mention that these extremely high lumens/watt claims do not take into account how much of the light actually hits the desired target area. Use of reflectors, shields, ballasts, ambient temp, etc reduce overall efficiency.
TheImpatientGardener said:
Please point out what I said that isn't correct. This wasn't a technical discussion about lighting efficiency so I didn't bother to type the wall of text that I already said several times on this forum. If you want the lumens/watt numbers on all the popular lights, I posted them a couple of weeks ago with some help from Willard3.
TheImpatientGardener said:
If someone shows me a source for LED lighting is more efficient than 130 lumens/watt that HPS is, I'll change my opinion, but current Wikipedia information puts LED lighting at under 100 and varying with colors. MH is right at 100.
Jeff H said:
Well, let me rephrase that. The WAY that efficiency is measured for ambient or direct lighting doesn't have significance in growing plants, as I mentioned earlier. Lumens is irrelevant when comparing a white light source to say, red or blue. http://en.wikipedia.org/wiki/Luminous_efficacy
Also lower on that page it lists efficiency of LED and HPS, both peak at 150 lm/w. This material is outdated though as LED technology is advancing very rapidly. We are now at 276 lm/w (granted that is a specific company under laboratory conditions, there are also fluorescent bulbs that are pushing 140 lm/w). http://www.cree.com/news-and-events/cree-news/press-releases/2013/february/276-lpw
I'm not trying to argue that one is "better" than the other, but comparing lights based on lumens for growing plants is flawed. Using that logic, comparing lights based on efficiency of lumens/watt is also flawed.
EDIT: forgot to include the link for the fluorescent tubes http://www.samsung.com/global/business/led/support/news-events/news-detail?contentsId=165 as you can see, that efficiency is greater than the 130 lm/w of HPS, but is irrelevant anyway.
Not looking into LED for the lumens, just trying to see how much a plant would need to find a common denominator between all light sources. I'm making the assumption that the direct light & dialed in spectrum coverage, can lead to a more efficent system. As in less lumes & less watts using LEDSarge said:
Agreed, and this is where I think (if possible) LED's can be more efficent. By using less Lumens/Watts/Heat with a dialed in spectrum and more focus light.TheImpatientGardener said:
Interesting links TIG, but you obviously can't buy any of those yet. Technology is definitely advancing. At one point incandescents were cutting edge technology.
As for the most efficient buld we can get at most stores, that would be the HPS bulb. Now measuring efficiency in watts/lumen is how it is done. That doesn't make it best for plants. Arguably, you could have an extremely efficient green light but it won't do anything for a plant because they don't absorb green light.
As for the most efficient buld we can get at most stores, that would be the HPS bulb. Now measuring efficiency in watts/lumen is how it is done. That doesn't make it best for plants. Arguably, you could have an extremely efficient green light but it won't do anything for a plant because they don't absorb green light.
llbuckshotll said:
I guess a better question would be how large is your plant, and how many plants do you have/want to keep? If it is only a couple mature plants I might suggest looking for a "UFO" solution around 50-90w as it looks like they are easy to hang and would provide sufficient light for a medium size plant (maybe 2-3 ft in diameter) but I can't attest to their penetration or coverage as I have never used them. I think getting multiple smaller wattage LED grow lights would give you more coverage than a single larger unit.
A more traditional LED light such as what I use (a 270w and 240w, with a 180w on the way) would probably be sufficient for a larger mature plant, as I have seedlings and juveniles growing alongside tall plants (light is probably atleast 18-24 inches away) and the juvenile plants are starting to flower. If I were to move the lights say, 18 inches from the top of my larger plants, the coverage would be quite large.
I'm expecting my 180w box type LED light to perform very well also. I think I can get more spacing out of my lights to increase my grow area so I'm experimenting with getting lower wattage led units and seeing the results.
TheImpatientGardener said:
Thats what I'm thinking and where I'm headed
Jeff H said:
True, but with "white" LEDs really being a combination of blue, green, and red light, I'd be curious to know how efficient they really are at producing a true white light. I can imagine that some of the efficiency is lost by producing the red light to adjust color temperatures. I just like knowing that almost none of my light is wasted in the green-yellow spectrum, which is exactly what produces the "brightness" or lumens that a bright light produces. Look at this graphic http://en.wikipedia.org/wiki/File:CIE_1931_Luminosity.png and compare it to http://hyperphysics.phy-astr.gsu.edu/hbase/biology/imgbio/chlab.gif
I like knowing my lights are producing 380 nm, 425nm, 460nm, 630nm, 660nm, 730nm wavelength light.
I love how everybody that wants to purchase lights to grow chiles becomes an instant expert on lighting.
I do lighting design for a living and lighting efficiency is defined as lumens/watt. Any other definition of lighting efficiency is bunk.
Anybody who uses Wikipedia as a source doesn't have any respect for science.....Wikipedia is unvetted crap.
I do lighting design for a living and lighting efficiency is defined as lumens/watt. Any other definition of lighting efficiency is bunk.
Anybody who uses Wikipedia as a source doesn't have any respect for science.....Wikipedia is unvetted crap.
Absolutely true.willard3 said:
But not necessarily applicable.
This is true for, lets say 'light in a room viewable to humans'. Yes the more lumens/watt the brighter the space will be for less money.
Our application is with respect to the growth of chillies. Basically the efficiency were looking for is growth/watt. As in the minimum amount of watts needed to fully
satisfy a mature plant with light.
Now if you make the statement, "chillies will all grow the same amount if equal amount of lumens are supplied by any type of light" (assuming all other variables equal). Then both statements are equal and efficiency is lumens/watt. But this is where the argument gets complicated.
I'm theorizing that with the LED's applying more of their light in the direction needed, being closer, & using only the wavelengths necessary that the same growth can be achieved using less lumens.
If this is true, then at some point the LED's will essentially be more efficient as less lumens and less watts are needed to achieve the same growth. Now even if less lumens are needed we still need to cross the threshold of efficiency(<--made up term
). They may require only a small amount of less lumens and the lesser efficient LED's may still consume more watts.I've ordered some of these and plan on running them off an old computer power supply:
http://www.ebay.com/itm/141096327397?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649
I have 3-4 bulb T12 fixtures and 2-4 bulb T8 fixtures. I havent figured out the math yet, but intend on setting up some experiment to see if the LED's can out perform these fixtures.
I've seen a post on here where someone did pretty good with older smaller LEDs and only using 45 Watts. Im currently pulling 5.5 amps/660 watts for my 5 fixtures and its not enough light. This is also $60+ month for me, so I need to find some where to cut cost if possible.
llbuckshotll said:Absolutely true.
But not necessarily applicable.
This is true for, lets say 'light in a room viewable to humans'. Yes the more lumens/watt the brighter the space will be for less money.
Our application is with respect to the growth of chillies. Basically the efficiency were looking for is growth/watt. As in the minimum amount of watts needed to fully
satisfy a mature plant with light.
Now if you make the statement, "chillies will all grow the same amount if equal amount of lumens are supplied by any type of light" (assuming all other variables equal). Then both statements are equal and efficiency is lumens/watt. But this is where the argument gets complicated.
I'm theorizing that with the LED's applying more of their light in the direction needed, being closer, & using only the wavelengths necessary that the same growth can be achieved using less lumens.
If this is true, then at some point the LED's will essentially be more efficient as less lumens and less watts are needed to achieve the same growth. Now even if less lumens are needed we still need to cross the threshold of efficiency(<--made up term
I've ordered some of these and plan on running them off an old computer power supply:
http://www.ebay.com/itm/141096327397?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649
I have 3-4 bulb T12 fixtures and 2-4 bulb T8 fixtures. I havent figured out the math yet, but intend on setting up some experiment to see if the LED's can out perform these fixtures.
I've seen a post on here where someone did pretty good with older smaller LEDs and only using 45 Watts. Im currently pulling 5.5 amps/660 watts for my 5 fixtures and its not enough light. This is also $60+ month for me, so I need to find some where to cut cost if possible.
You've got the right idea. Be careful with power supplies, they can EASILY kill you if you don't know what you are doing, or attempt to modify them/open them.
willard3 said:
I'm an engineer and I understand efficiencies better than you might think, I think I'm qualified to chime in on this topic.
Efficiencies can be anything from watt/watt, heat/heat or lumen/watt. It really depends on what YOU are measuring. One light could put out 100% UV-B (or blacklight) light and still be 80, 90, or 100% efficient, but using the lumen/watt method you would consider it to be 0 lumens/watt, completely inefficient. Lumens/watt is only worth mentioning if you are using a light for visibility and even then, color temperature is a factor and should be considered when making your decision. For growing plants, lumens/watt means almost nothing (unless your plants have sensitive eyes or are scared of the dark
)Taken a few electronics classes on my path to BS in Comp Eng Tech @ RIT (even though I dont use itTheImpatientGardener said:
You've got the right idea. Be careful with power supplies, they can EASILY kill you if you don't know what you are doing, or attempt to modify them/open them.
I'm an engineer and I understand efficiencies better than you might think, I think I'm qualified to chime in on this topic.
Efficiencies can be anything from watt/watt, heat/heat or lumen/watt. It really depends on what YOU are measuring. One light could put out 100% UV-B (or blacklight) light and still be 80, 90, or 100% efficient, but using the lumen/watt method you would consider it to be 0 lumens/watt, completely inefficient. Lumens/watt is only worth mentioning if you are using a light for visibility and even then, color temperature is a factor and should be considered when making your decision. For growing plants, lumens/watt means almost nothing (unless your plants have sensitive eyes or are scared of the dark
), so if I die at least I don't have to pay any more student loans 
but I should be good 
.Scared of the dark....lmao...
There are a bunch of resources on the net to modify old power supplies to use as DC power supplies. I have one I did a few years ago but it will only put out about 15 or so amps at 12v. YMMV....IIRC, it doesn't take much more than the right resistor on the 5v leads to make it work but please look it up, it has been several years since I did thisllbuckshotll said:
TheImpatientGardener said:
It is interesting that it is usually engineers and designers that get into these technical discussions. My degree is also in engineering,
The other thing to observe here is that Cornell's greenhouse, where they grow for both research and market, uses HID for light source. I will guess they did their research before they purchased..
LED is pretty cool and eventually may catch HID for efficiency, it just hasn't happened yet.
Read pond area lighting:
http://www.cornellcea.com/attachments/Cornell%20CEA%20Lettuce%20Handbook%20.pdf
LED is pretty cool and eventually may catch HID for efficiency, it just hasn't happened yet.
Read pond area lighting:
http://www.cornellcea.com/attachments/Cornell%20CEA%20Lettuce%20Handbook%20.pdf