As an LED grower I get asked a lot of questions about panels, and what's right for different setups. Sadly the usual scenario with LED threads is that they quickly turn into a debate about the which is better - traditional HID lighting or LED.
What I'm posting below has been cobbled together from a few posts I've made over the weeks about LED lighting generally and what you need to understand if you are seriously thinking about investing in LED lighting for horticultural purposes - ie, to grow your stash!
I'm not going to get into a debate about which is better - for me that argument is completely irrelevant. What is relevant is that we are able to choose our lighting setup to suit our own individual needs and requirements - much like we choose whether we grow in soil, coco, pebbles or water; if we grow in soil do we grow organically or chemically, if we grow in coco what system do we use? There are sacrifices and trade-offs with whatever system and set up we eventually go for. The intelligent grower will choose their lighting set up, growing medium, nutrient system, etc, etc, to suit their own requirements. The intelligent grower will then seek to maximise on the setup they've chosen, whether that's growing the biggest plant, the smallest plant, having the highest yield, the most seeds, the most variety, the lowest carbon footprint, the smallest energy bill, the lowest water consumption, whatever those factors or combination of factors are.
Solid state/LED lighting is currently still in its relative infancy. This is a semiconductor business, after all, and as such it is lalloping along in leaps and bounds. We have seen improvements in the diodes, the implementation of lenses and combinations of different types of lenses, improvements in the heatsinks, the circuitry and the spectral ranges available. Like any semiconductor subfield, advances appear rapidly to start and then plateau with time - and like any other semiconductor business, they follow various laws and predictable trends, both in development, cost and use. There have, however, been some major advances in the last two years and it is simply unrealistic to compare panels from even two years ago with what is currently available.*Each decade LED prices have fallen by a factor of 10, while performance has grown by a factor of 20. This phenomenon is known as Haitz' Law*(Steigerwald et al., 2002). The*implementation and mass production of LED lighting arrays for other purposes and industries will also significantly reduce the cost of solid state lighting.*
The lighting industry is changing, whether we like it or not. A Wired report from the 2011 Lightfair states: 'if all goes according to plan, the provisions of 2007′s Energy Independence and Security Act will effectively ban 100-watt incandescents starting in 2012. Seventy-five-watt bulbs will depart in 2013, followed by 60- and 40-watt lamps a year later. So the race to find a suitable replacement technology is coming down to the wire. The industry is banking on LED lighting as the way forward, and it’s virtually the only bulb technology on display: There is barely a single incandescent or sickly compact fluorescent to be seen. Just 200,000 square feet of companies racing to fill their share of the world’s billions of standard sockets—and betting on LEDs as the way to do it.'*
And from what I understand further developments will either ban traditional high pressure sodium vapour lamps in around two years time (April 2015) or demand that existing technology becomes more efficient.*
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Because LED lighting for horticultural purposes is still in its relative infancy, it is an emerging market and as such it is suffering at the hands of*entrepreneurial*but aggressive marketeers who have seen opportunities within our arena, and understand how little bargaining power we have for various legal reasons. In addition, we are suffering because the plant we grow has particular spectral requirements, and advances in our understanding of what these particular requirements are have been slow because obviously what we're growing is illegal. It has only been within the last 12-18 months that panels have started to become available that utilise a sufficient spectral range necessary for growing the plant through its complete life cycle.
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There is a lot of well meaning but slightly misguided (and often downright misleading) information on LED. If you want to grow with LED it is important to understand how the panels and diodes work and will work in your particular space. It is not simply about overall power output of the panel - all that does is give the grower an indication of the physical growing area that panel will cover. It is not about the power of the individual diodes within the panel - that just gives the grower an indication of the depth penetration of the panel, the necessary height that panel needs to be above the canopy, and whether you need to consider a SCroG or can leave your plants untrained. It is a combined and considered understanding of the overall power output of the panel, the power of the individual diodes comprising that panel, the lenses and combination of lenses used to focus the diodes within that panel, and the colour spectrums and spectral ratios used within the panel.
Plant lighting applications require a large number of individual diodes, not single high output diodes! For various physical reasons - mainly the droop effect, t
he 1w diode*(which draws 0.85w)*will always be the most efficient diode there is for our purposes - for reasons of pure physics. The 3w diode gives a nice tradeoff between depth penetration and efficiency (and draws an average of 2w - 1.8-2.2w, depending on colour spectrum). I haven't seen any grows utilising 5w diodes but aside from their inefficiency, - they draw just over 3w. I can't see how they will be that useful for the average grower as the power of those diodes means that they have to positioned at a substantial height from the canopy to avoid bleaching - 3w diodes already need to be placed a good 15-18 inches above the canopy.*
Let me repeat the above statement; there is an exponential drop in diode efficiency as the potential output of the diode increases from 1-3-5w.*
The other aspect to consider is that in a 100w panel, consisting of 1w diodes, you will get 100 1w diodes. In a 100w panel consisting of 3w diodes, you will get around 30 3w diodes, and in a 5w panel, I guess around 20 diodes. This means that as far as horizontal coverage goes, the 1w diodes outshine (if you'll pardon the pun) the others - again, simple physics.*
For most growers all they will need is a panel comprised of 3w diodes but using a combination of 30, 60 and 90 degree lenses, which give a nice balance between horizontal coverage and vertical depth penetration. They then need to ensure that they have a sufficient combination of colour spectrums covering blue, red, far red, orange, UV, white and green. The final consideration (ie, do I need a 200w panel, a 300w panel or two, 200w panels) is determined by their physical growing space.
If you are seriously considering LED then I urge to spend some time digesting the information on the following website:
www.ledgrowlightsreview.org
This is an independent site, set up by a guy who*as far as I can tell has no agenda or affiliation and he's not actively pushing LED or selling anything (which goes down well with me). He's just laying the cards on the table.*
It combines basic information, technology, news, reviews and interviews. The reviews and the reviews combined with the interviews make for interesting reading and they do help you get a feel for what's right for you or what might suit your situation.*
b, THERE IS SOME REALLY USEFUL INFORMATION THERE - a lot of very useful information, clearly explained. It's worth reading as much of it as you can - especially the tech. And then when you've read it all and think you understand it, go back and reread it, and then smoke a blunt and read it some more until you understand what's what.*
I will say it doesn't look as though it's been updated in a while so if you're looking for a review of the latest panel you may not find it, but the tech stuff is bang on.
Growing with LED is not the same as growing with HPS. With HPS you can buy a bulb, buy a ballast, buy a shade, plug them all in and you're off - essentially (i realise there are considerations within that). You do have to think a bit harder with LED; you have to work out the right combination of output (for coverage), diode strength and focusing lenes (for penetration) and then you consider your wavelengths. Cannabis is quite demanding light wise. It's not a simple plant in that respect and unless you have the correct spectral field in your panel, it doesn't matter how powerful it is, it ain't gonna cut the mustard. And it has only been within the last 12 months or so that the correct spectral requirements have been incorporated into these panels.*
As a scientist, when I set up an experiment, I research, read, plan and prepare before finally executing. Please take the time to do the same with LED. I can't state this clearly, plainly and frequently enough; if you want to grow with LED, take some time to understand what you are getting into and how the different factors interplay and relate to each other - in other words, LEARN THE TECH! LED panels - even those from China - are relatively expensive, and may well be the most expensive item in your setup. Combine this with the unscrupulous nature of the current LED market, and it is the fool who enters the arena unprepared!!
So here it is again, for anyone interested in LED lighting for horticultural purposes:
www.ledgrowlightsreview.org
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