Will LED lights ever....

HockeyBeard

HockeyBeard

Well-Known Member
Yeah, we'd be looking at similar results. Keep that canopy even and packed is the key to taking advantage of the benefits of LED.

a mongo frog said:
But lets say i match you and through 15 plants in that 5x5 area and prune the lowers effectively getting the same thing as your scrogg. We are talking about the same thing right? Because it wouldn't matter the ppfd numbers are there? Im still trying to gather info on these cobs as well. So don't get mad if it seems like your doing my home work for me. Im just asking questions.
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Rahz

Rahz

Well-Known Member
Average PPFD provides an almost exact comparison, minus possible spectral deficiencies/advantages. PAR watts is almost as good as knowing the average PPFD. Either one is close enough to get a good estimation of a light's capability.
 
HockeyBeard

HockeyBeard

Well-Known Member
Right, I was just using training techniques, or lack there of, to note that there'd be a difference in yield. You can't do the same thing you'd do under a Gavitas on 10ft ceilings as you'd want to do on an LED at 24-36inches.

But trained properly, could go toe to toe with it and provide a litany of other benefits such as a fraction of the heat and better spectrum.
 
a mongo frog

a mongo frog

Well-Known Member
HockeyBeard said:
Right, I was just using training techniques, or lack there of, to note that there'd be a difference in yield. You can't do the same thing you'd do under a Gavitas on 10ft ceilings as you'd want to do on an LED at 24-36inches.

But trained properly, could go toe to toe with it and provide a litany of other benefits such as a fraction of the heat and better spectrum.
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Really? Why not then? Im all confused now.
 
Rahz

Rahz

Well-Known Member
HockeyBeard said:
Light height directly factors into PPFD calculations.

@Rahz Am I missing something here?
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Light height doesn't factor into PPFD calculations but does figure into PPFD spot readings. IE- Photons from a lamp is a set amount, space is a set amount, so average photon density (PPFD) in that space is calculated as a set amount.

To keep things simple for HID users I would suggest just comparing the PAR watts of various fixtures/emitters. That figure actually gives a handicap to HID due to reflective losses, but hey, it's easy. And down the road one will find the LED performs better than the PAR rating indicated. Bonus.

For instance, a 600w HPS at 35% efficiency is 210 par watts. Two of my T3-2100s (or 6 CXB3590s at 2.1 amps) provides 232 par watts using about 460w, not including driver loss and fan. Without reflective considerations the LED seems to be just 10% more light but it will produce a good bit more than that... but there's no simple way to give an exact figure.

Creating a PAR footprint for two specific lamps can provide a good comparison, but could still be confusing, for instance if one lamp had higher readings in the center but lower readings near the outer edge.
 
Yodaweed

Yodaweed

Well-Known Member
Rahz said:
Light height doesn't factor into PPFD calculations but does figure into PPFD spot readings. IE- Photons from a lamp is a set amount, space is a set amount, so average photon density (PPFD) in that space is calculated as a set amount.

To keep things simple for HID users I would suggest just comparing the PAR watts of various fixtures/emitters. That figure actually gives a handicap to HID due to reflective losses, but hey, it's easy. And down the road one will find the LED performs better than the PAR rating indicated. Bonus.

For instance, a 600w HPS at 35% efficiency is 210 par watts. Two of my T3-2100s (or 6 CXB3590s at 2.1 amps) provides 232 par watts using about 460w, not including driver loss and fan. Without reflective considerations the LED seems to be just 10% more light but it will produce a good bit more than that... but there's no simple way to give an exact figure.

Creating a PAR footprint for two specific lamps can provide a good comparison, but could still be confusing, for instance if one lamp had higher readings in the center but lower readings near the outer edge.
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Light height factors into footprint and factors into PAR calculations, that's why they do par readings at 18, 24, 30 inches.
 
G

grouch

Well-Known Member
Gquebed said:
Efficiency is irrelevant. Results are.

But to play the math game... suppose 4 pounds is the absolute max that can be yielded from strain X in a 5x9 space and that such can be done with 2 x 1000w HIDs. Now what would it take with quality LEDs to get that same 4 lbs??

That is all i am asking. Efficiency is irrelevant to me. I want the 4 lbs, not pennies saved on electricity.

Why cant i get a straight answer on this question???
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A 5x9 space is a two dimensional measurement. If the space is 8 ft tall you could run two 4 foot tall sections with 45 50w cxb-3590 in each section. At 1gpw you could theoretically produce 10 pounds in that foot print.
 
Rahz

Rahz

Well-Known Member
Yodaweed said:
Light height factors into footprint and factors into PAR calculations, that's why they do par readings at 18, 24, 30 inches.
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There's a difference between calculations and readings. It's possible to get a rough PAR calculation from multiple readings, but not as simple as just adding up all the readings and averaging them.

OTOH, a photon density calculation is A- the number of photons a lamp emits, B- the space. Both of those are constants, so the average photon density will also be a constant and has nothing to do with how high the lamp is.

It's the same with PAR watts. You don't calculate the par watts based on a reading. It's the efficiency of the lamps * the wattage output.
 
BigZcolorado

BigZcolorado

Well-Known Member
Im running mine at 28-32 away as recommended. I tryed closer the plants said no. 1gpw is what i average with a 600w hps if your wanting to run cobs start thinking more like 2gpw if you can grow.
Cobs/les lights are on a whole new level! all my hps/mh lighting is up for sale or sold, they worked better as heaters than grow lights anyways.
 
guod

guod

Well-Known Member
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Rahz

Rahz

Well-Known Member
The basic math for average PPFD is simply light emitted and the space in which it's being emitted. I'm not sure why this is controversial. I understand the inverse square law. Light height and beam angle change the distribution. If done poorly it can result in greater reflective losses, but beyond the reflective losses it doesn't increase or decrease the average PPFD of a particular light in a particular space.

The point being, if you want to compare two lights without having them available for testing, you can determine the PPFD and/or PAR watts without taking any spot readings provided you know the output, efficiency, and spectrum.
 
Yodaweed

Yodaweed

Well-Known Member
Rahz said:
The basic math for average PPFD is simply light emitted and the space in which it's being emitted. I'm not sure why this is controversial. I understand the inverse square law. Light height and beam angle change the distribution. If done poorly it can result in greater reflective losses, but beyond the reflective losses it doesn't increase or decrease the average PPFD of a particular light in a particular space.

The point being, if you want to compare two lights without having them available for testing, you can determine the PPFD and/or PAR watts without taking any spot readings provided you know the output, efficiency, and spectrum.
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....you just don't get it.

The intensity (or illuminance or irradiance) of light or other linear waves radiating from a point source (energy per unit of area perpendicular to the source) is inversely proportional to the square of the distance from the source; so an object (of the same size) twice as far away, receives only one-quarter the energy (in the same time period).

I will make it easy, the further away the less light, not the distribution...
 
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Yodaweed

Yodaweed

Well-Known Member
You are basically saying it doesn't matter how far from the sun we are...have you looked at the closer planets to the sun? They are freaking cooked!
 
Rahz

Rahz

Well-Known Member
Yodaweed said:
....you just don't get it.

The intensity (or illuminance or irradiance) of light or other linear waves radiating from a point source (energy per unit of area perpendicular to the source) is inversely proportional to the square of the distance from the source; so an object (of the same size) twice as far away, receives only one-quarter the energy (in the same time period).

I will make it easy, the further away the less light.
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You're telling me nothing I don't know. A spot reading is influenced by the height of the light source and it's emission pattern. If you raise the light the reading in that spot will go down, as you say due to the inverse square law.

But that doesn't mean there's less light in the space. If you stick your light down 1 inch from a plant the PPFD reading will be extreme. Does this mean the light density in the grow space is higher? No, it does not. By lowering the light you are also decreasing the PPFD readings in the outer areas. The average remains the same. This is not a difficult concept.
 
Yodaweed

Yodaweed

Well-Known Member
Rahz said:
You're telling me nothing I don't know. A spot reading is influenced by the height of the light source and it's emission pattern. If you raise the light the reading in that spot will go down, as you say due to the inverse square law.

But that doesn't mean there's less light in the space. If you stick your light down 1 inch from a plant the PPFD reading will be extreme. Does this mean the light density in the grow space is higher? No, it does not. By lowering the light you are also decreasing the PPFD readings in the outer areas. The average remains the same. This is not a difficult concept.
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I still don't think you grasp the concept of if you raise your lights PAR readings get lower. Hence why you can raise a single light source that outputs more lumens higher than multiple that output less. Simple mathematics, that's why LED's aren't in the same realm as HID lights yet at least for commercial settings, once you raise them above 2-3 feet the intensity just isn't there. Not too many warehouse grows gonna hang their lights that close, kills the footprint.
 
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