I won't quote anyone because this thread is just too jam packed full of rubbish I'd be here all day. LedGrow has said some pretty convincing counter arguments to the dribble that has been said and there are still stubborn and under educated people trying to argue their misinformed point of view. If you would like to get up to speed with the whole LED thing please read below:
First a little History:
I am a Mechatronic Engineer and have been serious about researching LEDs for growing for 4 years. When I started my research, LEDs were not up to scratch to effectively grow plants! The theory was there but not the production. In the year 2000 SolarOasis engineers developed and manufactured the world's first commercial LED plant grow light, it was insanely expensive then and it still is now and it is still ineffective. Around 2005, Hype about High Power LEDs started to get people interesting in the potential of LEDs. Then people started to advertise "LED Panels" as so called "LED Grow Lights" that still used 5mm LEDs and were also severely under powered. But unlike The Grow Bars from Solar Oasis they only used 470nm Blue and 625nm red LEDs which are the cheap, common LEDs. The forums lit up with people asking about grow lights and there were many making their own. The realisation of the Procyon 100 light was the first commercial example that I was aware of that used high power LEDs. Unfortunately it doesn't work as it was hoped either. It contains only Cree Red and Blue LEDs which are not actually aligned to the Photosynthetic response of both Chlorophyll A and B as much as they try to tell you. Thus, is not only inefficient, but is missing other colours that we now know are also important (UV and FR. Other manufacturers produced similar lights like the famous UFO light that has been so heavily copied in china. More powerful lights began to emerge from china but still restricted to the Red/Blue mostly due to cost, but also due to demand to get any old LED grow light into the market.
The LED Lighting market is developing at an extremely fast pace and research and development is increasing the efficiencies at an exponential rate, and the cost of LEDs are coming down dramatically. As of January 2009 there has been a breakthrough that promised to be able to reduce the production costs of LED dies by 90%. As that sort of technology filters through to the manufacturers and LEDs become used as the predominant lighting source, the retail price will drop even further. Lights are developing and since early 2008 TriBand and QuadBand LED lights have begun to emerge as the manufacturers have realised that the RED/BLUE lights are failing to produce results in budding/flowering. These new lights can have UV (395nm), Royal Blue (455nm), Orange Red (630nm), Deep Red (660nm), and FR (730nm).
There is no point sitting around crying that your UFO that you bought of Craig's list isn't working. Don't come to forums to whine that LEDs are no good and people should stick with HPS. If you had done your research you would know that its not the LED technology that are failing you, it is the mis-use of the technology and mis-representation of what LEDs are capable of. With such a cut throat market, and a mass of stupid people, of course people are going to cash in on the LED hype. But the Fact remains, LEDs will be the future of indoor growing whether you like it or not. Companies are using the revenues from sales of crappy LED Lights to fund the research that is required to produce better lights.
As for penetration, light is Light, the difference is the frequency. A possible explanation why light from a MH or HPS would "Penetrate" the plant canopy better is because plants do not absorb green/yellow/orange light very well. The light either passes through or is reflected, giving the lights chance to bounce around and get further down to lower leaves. These frequencies are not absorbed by plants, so the perceived increase of light penetration of a HPS does not mean that your plant is getting more usable light.
Next point I would like to make. LEDs are a different light source. Its not like removing a Metal Halide and putting in a HPS. They don't emit light in the upper infra red region (radiant heat). This is both good and bad. GOOD because it will be the end of frying your leaves and buds and end to wasted energy and end to noisy, expensive extraction fans and carbon filters and greatly reduced heat signature! But BAD because during winter your indoor grow may end up being too cold. You may need to think about not only ventilation but heating as well. But that is not the end of it. If you have tried growing with 600W or 1000W HPS you end up having to ventilate your grow area in order to cool everything down due to the enormous amount of heat generated by the lighting. If you want to add any CO2 its much like an open fire, 90% will go straight up the ventilation shaft. The use LEDs makes it possible to seal off the grow space and introduce CO2 without it all blowing away.
The rated lifetime of LEDs is often stated as 50,000 hrs, it is incorrect to assume that after 50,000 hrs the light is no longer usable. The figure means that in 50,000hrs the light output will be 70% of its original brightness. And in 50,000hrs after that is will be 70% as bright as it was after the first 50,000 hrs, so in theory will just get duller and never actually die. (As long as the power supply can keep going that long)
So now we have a light source that uses half the energy to produce the same results, doesn't burn our plants, and reduces suspicious electricity bills. LEDs make it possible to eliminate smells and open the way for increased production through CO2 supplements. LEDs have an instant on (no warm up) and no cycle times we have to worry about. No more dead timers from the inductive load of inductive ballasts killing the relays and won't need replacing for a long time.
Unfortunately LEDs are not cheap! It is the efficiencies and features I mentioned above that make LEDs so promising. If you are trying to grow on the cheap, LEDs may not be for you. However, you can get a single 600w LED 5 Band LED light for less than US$900 posted to your door. If you can make that back in less than 6 months, the next 7-10 years is all profit and much more stealthy.
Just don't go around saying they don't work as well as a 600w HPS until you have tried a grow with 600w LED using UV, BLUE, RED, Far RED LEDs. Please Please Please don't go around saying, "I have tried LEDs and they suck" when all you have done is stick your plants under a 10w LED panel off eBay!!!
Regards
Phil
I've gotten good at making cheap led arrays using only the best, phillips lumileds. I have yet to / I am in progress with testing, however, I think densities of around 300 watts a square foot in dees are more than sufficient to be driving remarkable fruit growth, especially in something like a sog set up.
