Designing a new LED grow light system? Help please...

Hey everyone, I'm new to the site, but not to the hobby.

I am thinking about designing and possibly manufacturing a cost effective LED lighting system. I think these systems are the way of the future, but the current available systems seem to be slightly outdated because LED technology changes so often. I have read a great deal of information regarding LED's vs. HID's. That being said, there still seems to be some confusion and lack of continuity of scientific information out there. This thread is designed to gather input from those of you that are "pros" in this. Please contribute openly.

LED systems that are currently available utilize specific wavelengths, usually blue & red. From my very basic understanding, chlorophyll a peaks both at 430nm AND just slightly less at 662nm. Chlorophyll b peaks at 453nm and then slightly less at 652nm. The currently available LED systems usually only push two wavelengths, the two major ones for chlorophyll aborbtion, which push ATP and NADPH. While I know that plants primarily use certain wavelengths of light, there are other wavelengths that are needed by plants, such as beta carotene, phycoerythin and phycocyanin. Plants need more than two wavelengths, not that it can't be done by two, obviously. I am slightly skeptical of capitalism when it comes to producing the best product. I'm curious if years ago, vendors jumped on the LED bandwagon and pushed inferior products with specific wavelengths (emitters that were cheaper than white, not better) in a rush to get on the front of the LED market to make bigger profits, not better products.

Would it be beneficial to create LED grow systems that use white light instead of the narrow spectrums that are available now? I know that much of the needed wavelengths are in blue/red, but there ARE others. I have a supplier than can provide 10W, 20W, 50W, 100W and 200W LEDs in 6500K-7000K white ("full spectrum"). They can also provide me with 10W, 20W, 50W and 100W red & blue (of appropriate wavelengths).

I have two real questions here, with some sub questions...
1) Is it worth inventing a high powered WHITE LED system that covers all spectrum? And if so, how highly powered would be smart? Would it be marketable to create powerful WHITE LED systems, like a true 600-1000W (or more), simply because of the savings in cooling costs compared to HIDs?
2) If the above question isn't feasible or marketable, would it be worth creating a higher powered LED system that utilizes the traditional 2 wavelengths? Would there be any growing advantage to using the 10W, 20W, 50W or 100W red/blue spectrums (for 250-1000W+ total in the 2 spectrums) instead of the current lower powered systems that are available? Would the extra lumens provided by a high powered 2 spectrum system like this provide any benefits in comparison to the available products out there? Again, this concept like the WHITE LED concept, would also be more about the savings in cooling costs instead of only lower power usage.

It seems this technology has come a long ways since the days of 1W, 3W & 5W bulbs.

What do you all think? Is there any logic to what I'm thinking about creating, or am I trying to illogically reinvent the wheel?

I am hardly an engineer, or fully educated scientist, which is why I'm here getting input. Please chime in.

If you want really scientific information, search for the "Grow LED" thread on candlepowerforums. In this thread, many LED specialists (coming from the flashlights mainly) discuss with biological researchers. It is a very good starting point because there is pretty much all the info you need to know.
There also are some explanations that you can find in the "led for horticultural lighting" paper published by Osram OS, which pretty much states the same things discussed in the thread I mentioned above.

What I understood from this thread is that basically any wavelength in the visible spectrum can trigger photosynthesis but some wavelengths such as 620-670nm range have an absorption rate which is much higher. Moreover, 1 watt of red light produces much more photons than 1w of green light. Additionally, red LEDs can be very efficient; for instance the 660nm Osrams and Lumileds are 40% efficient at their standard current (400mA). That means that for every watt of electricity passing through the LED, 400mW of it is transformed into light and 600mW into heat. Those 400mW are photons that directly trigger the highest photosynthetic action on the plants. I don't have the exact figures for green light but basically green LEDs are at most 15 to 20% efficient (LED datasheet), carry about 15% less photons per watt (can be computed, keyword "ernergy per photon") and the photosynthetic action in the green spectrum is anywhere from 30 to 60% less depending on the studied plant (you can find many graphs representing photosynthesis depending on the spectrum but they aren't always very accurate).
A bit (5-20% overall) of blue light seems to be effective to trigger close internodal spacing mainly. Blue LEDs are the most efficient (the latest Deep blue Osrams are close to 55% efficient) but each watt of blue light produces more than 30% less photons than each watt of red light. So it's not wise to use blue as the primary source of light.

That, is why manufacturers went with the "blue/red" spectrum from the beginning. Technically, it is the most efficient use of LEDs because it aims for wavelengths where the action on the plant is the highest.

Now, regarding white light. Some people started to use white LEDs because they thought their efficiency was better. They looked at lumens, more specifically at lumens/watt and compared with blue LEDs and red LEDs. If you do a bit of research on that (basically looking at datasheets), you will see that white LEDs from the big manufacturers (Cree, Lumileds, Osram, etc.) reach 130 lumen/watt where the red and blue LEDs are only 50-70 lm/W. That is absolutely true, white LEDs have better luminous efficacy than color LEDs. But it is absolutely wrong to compare like that in a grow light perspective. The "lumen" is a unit that has been created to compare what light the HUMAN EYE can see the best. It doesn't represent the ACTUAL quantity of light coming out of a source.
If you look up for the "luminous function", you'll see that the curve reachs its peak at 555nm and is very low at 450nm and 660nm. What that means is that you need 683 lumens of green light to have a full 1 watt coming out of your light. In red (625nm), it is something like 150lm for 1 watt. All in all, it means that a 200 lumens green LED outputs in fact LESS light than a 50 lumens red LED. So what does this have to do with white?
A white LED is made from a blue LED with a phosphorous layer to "color" some of it into green (for cold white) or into amber (for warm white). Thus, a lot of the light coming from a white LED is in fact green or amber so its 130 lumens/watt does not mean that it outputs more light than a 70 lumens/watt red LED.

So what you're looking for when comparing LEDs to use in your grow light is the radiant efficiency. How much watts of lights are created for each watt of electricity consumed. It doesn't appear in most datasheet for white LEDs but you can approximately compute it if you have the emitted spectrum and know the luminous function. From what I found out, even the best white LEDs (Cree XP-G) are less than 40% efficient. Cool whites (5000k+) are the most efficient (around 40%) and warm whites (3000k-) are the least (less than 35%, for the best on the market).
"High wattage" (5w, 10w, etc.) white LEDs you can find from Chinese manufacturers are said to have a luminous efficacy of 80 lumens/ watt. Without much computation, I can safely say that they seem less than 25% efficient in radiant output.

Some others like white LEDs because it provides a full spectrum, or at least a wider spectrum than color LEDs. I'm not a biologist and I cannot say whether or not plants benefit from a light covering more spectrum.

In my personal opinion, I'd say that using highly efficient red, deep red and blue LEDs is the key for the best results. Using white as a main light source is basically like copying HIDs. But HID lights are already very efficient. I recall reading that depending on the bulb, they are anywhere from 25 to 35% efficient. That's why I think people will have a hard time beating HPS with only white LEDs. I think the key to really beat HPS lays in using light which strikes the highest absorption points in plants, which is mostly in the red spectrum.

I wrote that a but in a hurry and didn't put any link to source my info. That's bad. If you need further explanation/proof in any of this, I'd be happy to try to provide it.

^^ great post pat........+ rep

edit.....can't rep you again.....still a great post though

patrikantonius said:

...A bit (5-20% overall) of blue light seems to be effective to trigger close internodal spacing mainly.
Blue LEDs are the most efficient (the latest Deep blue Osrams are close to 55% efficient)
but each watt of blue light produces more than 30% less photons than each watt of red light.
So it's not wise to use blue as the primary source of light.

Click to expand...

In Jubiare's thread there was some of the same talk about the amount of photons,
but I'm not convinced that be course blue emit less photons, the fact that they carry more energy is irrelevant,
have you seen any evidence that blue is not hitting harder so to speak ?

"A red photon at 660nm have a energy of 1.879 eV"
"A blue photon at 442nm have a energy of 2.808 eV"

I see it as getting hit by a heavy weight(blue) vs. a light weight(red)
a blue led sends out fewer punches but is hitting 35% harder than red.

I got this info in the thread I was talking about http://bit.ly/MPMbKR

What many of them do not seem to understand is that 680nm is the most efficient wavelength absorbed by Chlorophyl A. This is because the energy of a photon at 680nm contains the exact energy required to raise the dimer chlorophyl A molecule at the center of an antennae complex to the necessary excited state that will allow the process to liberate an electron. Basically, allowing for variances in specific wavelength absorption rates, all absorbed photons from 380nm to 680nm will have exactly the same effect in the process to free up electrons. The difference is that the photons of shorter wavelengths than 680nm contain excess energy that the plant must then dissipate as waste heat. And since a photon is a photon is a photon - for a given amount of output watts - you will generate a lot more photons at 680nm than 380nm.

Click to expand...

The poster seem a genuine researcher on the matter and it is sourced with scientific papers.

Beautiful thanks !

So a "red" photon is sufficient to knock off a electron and the left over energy from a blue is converted to heat,
then it make perfect sense that more photons is better than fewer hitting harder.

I'm glad I'm useful to someone at least, because OP doesn't seem to be very interested in the subject

For the OP, a 1000w LED puts out as much heat as a 1000w HID. Both are about 40% efficient, meaning 60% is converted to heat. The only reason LEDs have a reputation of low heat output is they are generally much lower wattage in a given application and HIDs radiate their heat down onto your plants while LEDs convect their heat off the backside of the chip. A broad spectrum white LED would be cheaper to build as the chips are cheaper, but is counter productive. The efficiency of LEDs is in the ability they have of not wasting power producing the portions of spectra the plant doesn't use. The only reason some makers add white chips is the concern that the plants MAY need some light other than red and blue. We don't know all the details of the way plants use light. We haven't had the lights capable of isolating the different spectra until recently.

Red1966 said:

For the OP, a 1000w LED puts out as much heat as a 1000w HID. Both are about 40% efficient, meaning 60% is converted to heat. The only reason LEDs have a reputation of low heat output is they are generally much lower wattage in a given application and HIDs radiate their heat down onto your plants while LEDs convect their heat off the backside of the chip. A broad spectrum white LED would be cheaper to build as the chips are cheaper, but is counter productive. The efficiency of LEDs is in the ability they have of not wasting power producing the portions of spectra the plant doesn't use. The only reason some makers add white chips is the concern that the plants MAY need some light other than red and blue. We don't know all the details of the way plants use light. We haven't had the lights capable of isolating the different spectra until recently.

Click to expand...

Are you not missing the radiated heat in the light spectrum from a HPS bulb ?

That big IR peak at 770nm is bigger than the blue light, and you don't get that with LED's
The warmth I 'm feeling on my skin when I shine 660nm LED lights on it, is not IR but 660nm red converted into heat in the skin.

This thread LED heat VS HPS heat? has some of the same discussion if I recall correctly.

I think red is right, basically the main difference watt for watt between HID and LED is that for LED basically 40% of the heat is going downwards (light) and 60% is going upwards directly into the heat sink. With HID 100% is going everywhere. Both a watt of light and a watt of heat are basically heat. In fact 100% of the electricity coming into a LED is transformed into heat; but some of it are visible photons and the rest of it ??? something going into the heat sink. It's the same with HID.

On a side note, if we compare efficiency with HID, a 1000-watt Sylvania HPS outputs 1621 µmol/s. That's approximately 1.62 µmol/s/W
In comparison, a GD+ bin 2T, 48% efficient at 350mA, peak wl 660nm, outputs (0.480 J/s) / (3.00977e-19 J) = 2.65 µmol/s/W

Just to be sure, when we talk about efficiency, its in the conversion from electricity to usable plant light,
not lumen or PAR light where cyan-green-yellow counts as much as red/blue.

Looking at the spectrum I don't understand how using wattage on that can be equal to the watts burned off in a LED of pure 660nm red and 445nm blue.

I agree about the radiated heat vs the dissipated heat is all about how you calculated the efficiency.

Yes of course PAR efficiency is only one part of the story because it doesn't take into account the plants' absorption rates. But I think HPS bulbs have a more decent spectrum than MH anyway. The problem is (with HID) you need to go with 1000w bulbs to reach maximum efficiency whereas with LED, the lower the power, the better the efficiency. But anyway, I'm not here to debate HID vs LED, especially not with you

I think we all are right on the subject it's just the standard of measurement thats not invented yet, lumen vs PAR vs LEDPAR.

Rasser said:

Are you not missing the radiated heat in the light spectrum from a HPS bulb ? That big IR peak at 770nm is bigger than the blue light, and you don't get that with LED's The warmth I 'm feeling on my skin when I shine 660nm LED lights on it, is not IR but 660nm red converted into heat in the skin. This thread LED heat VS HPS heat? has some of the same discussion if I recall correctly.

Click to expand...

"HIDs radiate their heat down onto your plants while LEDs convect their heat off the backside of the chip"

patrikantonius said:

Yes of course PAR efficiency is only one part of the story because it doesn't take into account the plants' absorption rates. But I think HPS bulbs have a more decent spectrum than MH anyway. The problem is (with HID) you need to go with 1000w bulbs to reach maximum efficiency whereas with LED, the lower the power, the better the efficiency. But anyway, I'm not here to debate HID vs LED, especially not with you

Click to expand...

I thought PAR was designed to do exactly that. HPS bulbs put out very little blue light, almost nothing. Blue light in veg is required to prevent stretching. 600 watt HID bulbs are more efficient than 1000 or 400 watt. The 1 watt LEDs ARE more efficient than 2 or 3 watt, but fixture size can be problematic.

PAR is only measuring the quantity of photons in the visible spectrum (400-700nm). For instance both MH and HPS lights have a high PAR but HPS perform better in flowering because plants need larger quantities of red light than blue light. That's why PAR is not the only relevant information; the distribution of the spectrum is also crucial.

badassledsystems said:

Hey everyone, I'm new to the site, but not to the hobby. I am thinking about designing and possibly manufacturing a cost effective LED lighting system. I think these systems are the way of the future, but the current available systems seem to be slightly outdated because LED technology changes so often. I have read a great deal of information regarding LED's vs. HID's. That being said, there still seems to be some confusion and lack of continuity of scientific information out there. This thread is designed to gather input from those of you that are "pros" in this. Please contribute openly. LED systems that are currently available utilize specific wavelengths, usually blue & red. From my very basic understanding, chlorophyll a peaks both at 430nm AND just slightly less at 662nm. Chlorophyll b peaks at 453nm and then slightly less at 652nm. The currently available LED systems usually only push two wavelengths, the two major ones for chlorophyll aborbtion, which push ATP and NADPH. While I know that plants primarily use certain wavelengths of light, there are other wavelengths that are needed by plants, such as beta carotene, phycoerythin and phycocyanin. Plants need more than two wavelengths, not that it can't be done by two, obviously. I am slightly skeptical of capitalism when it comes to producing the best product. I'm curious if years ago, vendors jumped on the LED bandwagon and pushed inferior products with specific wavelengths (emitters that were cheaper than white, not better) in a rush to get on the front of the LED market to make bigger profits, not better products. Would it be beneficial to create LED grow systems that use white light instead of the narrow spectrums that are available now? I know that much of the needed wavelengths are in blue/red, but there ARE others. I have a supplier than can provide 10W, 20W, 50W, 100W and 200W LEDs in 6500K-7000K white ("full spectrum"). They can also provide me with 10W, 20W, 50W and 100W red & blue (of appropriate wavelengths). I have two real questions here, with some sub questions... 1) Is it worth inventing a high powered WHITE LED system that covers all spectrum? And if so, how highly powered would be smart? Would it be marketable to create powerful WHITE LED systems, like a true 600-1000W (or more), simply because of the savings in cooling costs compared to HIDs? 2) If the above question isn't feasible or marketable, would it be worth creating a higher powered LED system that utilizes the traditional 2 wavelengths? Would there be any growing advantage to using the 10W, 20W, 50W or 100W red/blue spectrums (for 250-1000W+ total in the 2 spectrums) instead of the current lower powered systems that are available? Would the extra lumens provided by a high powered 2 spectrum system like this provide any benefits in comparison to the available products out there? Again, this concept like the WHITE LED concept, would also be more about the savings in cooling costs instead of only lower power usage. It seems this technology has come a long ways since the days of 1W, 3W & 5W bulbs. What do you all think? Is there any logic to what I'm thinking about creating, or am I trying to illogically reinvent the wheel? I am hardly an engineer, or fully educated scientist, which is why I'm here getting input. Please chime in.

Click to expand...

You wouldn't be inventing anything. This product is already on the market as street lights, high bay lighting, etc. Buying an existing product and relabeling it is not invention.