LED: Watts/sq ft

[HighWaterMark]

What's the ideal conversion of Watts/sq. ft. for a bi-wavelength LED: 1. veg and 2. flower?

Is it 50W/sq. ft. all the way around (like HID) or does it differ with LED?

 

[HighWaterMark]

Running cooler (less wasted energy) I thought I could get away with a bit less Wattage/sq. ft. True? False?

 

[Hosebomber]

When you say bi-wavelength are you referring to 450 blue and 660 red or a switch that turns off some/most of the reds for veg only?

To answer your question, generally speaking if you have a high quality LED you can get away with 2/3 of the power rating you would use with HPS. ie use 400 watts of LED's in the same area you was using 600 watts of HPS. That is assuming you have a quality LED panel.

 

[HighWaterMark]

Hosebomber,

thanks for replying to my question. And yes, I'm referring to the switch (which I don't understand) that toggles from vegging to fruiting. Does it specify the wavelengths or does it change the overall power (penetration for LEDs, heat for HIDs)?

I found this resource (A Good Straightforward Guide To LED Grow Lights | KuleKat . com) claiming that traditional HID (MH/HPS) spill 2/3 of their effective wattage (as heat) outside the effective PAR. Is this what you were referring to?

Can you distinguish power rating from the Wattage posted on the website (if there is a difference)? I have a tough time deciphering Wattage from ads for LEDs.

Thanks again,
HWM

 

[ezmeds]

75% I think is a good rule of thumb. But you need to use a quality LED panel

 

[Hosebomber]

High, The switch on most current LED panels simple turns off a portion of the LEDs on the light. Mostly red leds are turned of and it reduces the amount of power drawn. This is also a good way to allow plants to get used to the intensity of the light they will be growing under. I believe SteveHman puts his on veg for the first day or 2 under the LEDs. Far red light induces stretching. This is the color of light that plants get when they are grown near other plants and it causes them to stretch to compete with the surrounding plants for the light.

There are a few things to realize with this "resource". It says directly in it how this tactic of using a web article or a review is just a marketing ploy. That is exactly what this is for that company that is mentioned 4 or 5 times. There is some good basic information in the article but is glazes over some of the more important things. Like the fact that there is Chlorophyll A, B, C1, C2, D, and F not just A and B. There are also over 30 other known photo receptors in most plants and up to as many as 50+.

The reason that I say 2/3 the power draw you would use with an HPS is simply due to my research and testing. It is possible to go even lower but the more you reduce your watts the more you have to adjust other things. Making a single overhead hanging light panel that works like the traditional HPS or MH light simply isn't the most efficient way to use leds... but people are adverse to change and things that require more work for them.

The easiest way to get actual power dissipation (the part you pay for on your bill) is to take the Amp x Voltage = Watts (for us customers on residential power at 60 Hz). Most companies are pretty good about giving you this data because they figure most don't know how to do the simple conversion. Another way to "guesstamate" is to take the number of LEDs and multiply that by .8 for 1 watt LEDs and 2.6 for 3 watt LEDs. 1 watt LEDs are driven at 350mA or .350A times that by the voltage 2.1 -3.2. The red LEDs tend to run on the lower side for forward voltage (Vf). The rest of the difference you get from the "kill-a-watt" is inefficiency in the drivers that convert the power from the walls AC mains to DC.

Hope I was able to answer your questions!

 

[HighWaterMark]

Hosebomber,

You mention in the third paragraph of your last post that a single LED (hanging above the center of your canopy, I assume) is a poor way to maximize growth. Specifically, you suggest that it's energy-inefficient.

What is your suggestion for relating the suspended LEDs to your canopy?

Thanks,
HWM

 

[Hosebomber]

Let me clarify, you want your light source above your plant. However, having a large number of LEDs in a small place is less effective than having a large number of LEDs spread over the whole area of your grow. This does 3 things: Allows you to have the lights closer to the plant for higher penetration, Spreads out the heat from the LED for longer life and higher color consistency, and spreads the light farther around the growing area.

In an idea situation, you would be able to have lights covering the sides and all of the top area and still use the same or less wattage with better results and get lower bud growth. The problem is, this isn't a 1 size fits all solution and requires the grower to: buy a lot of fixtures (like people currently do with CFLs), have all the knowledge and abilities of the LED light producers, and have a single source point to buy parts and components cheaply. None of these are likely or good options. Those that have the knowledge and ability to make LED strings, wire them up, find a way to mount and hang them, etc. generally don't have all of the botany knowledge required to know what wavelengths they need and in what ratios.

Therefore, the easy solution is to make an overhead hanging panel like everyone has been using for decades and make it a little less effective than it could be.

Hope I clarified that as much as possible.

 

[Bolivar]

Let me clarify, you want your light source above your plant. However, having a large number of LEDs in a small place is less effective than having a large number of LEDs spread over the whole area of your grow. This does 3 things: Allows you to have the lights closer to the plant for higher penetration, Spreads out the heat from the LED for longer life and higher color consistency, and spreads the light farther around the growing area.

In an idea situation, you would be able to have lights covering the sides and all of the top area and still use the same or less wattage with better results and get lower bud growth. The problem is, this isn't a 1 size fits all solution and requires the grower to: buy a lot of fixtures (like people currently do with CFLs), have all the knowledge and abilities of the LED light producers, and have a single source point to buy parts and components cheaply. None of these are likely or good options. Those that have the knowledge and ability to make LED strings, wire them up, find a way to mount and hang them, etc. generally don't have all of the botany knowledge required to know what wavelengths they need and in what ratios.

Therefore, the easy solution is to make an overhead hanging panel like everyone has been using for decades and make it a little less effective than it could be.

Hope I clarified that as much as possible.

I'm thinking about trying LEDs next grow myself. Do you mean we should get several smaller panels (with the same total wattage) to spread the light rather than 1 single panel? Or is there some other way to do it.