Some food for some minds:
"Great question. CREE have the best white lighting solutions available right now due to their high performance royal blue chips, remote phosphor patents and manufacturing techniques. Many of the smaller companies in the industry have started producing full white LED grow lights because of:
- the improvements in white LED's
- simplicity of the bill of material
- the fact it produces a working light which makes it easier to inspect the plants
- there is a range of larger power density emitters which provide a lower cost per watt solution
From our research, producing an LED grow light with just generic white LED's provides similar yields to that of most good quality HPS. High quality deep red LED like the CREE XPE or Lumileds Rebel which can produce light between 650-660nm at over 40%+ efficiency will have a much higher quantum yield per photon, less reflection and is what drives 80%+ of the growth/photosynthesis seen under any XXXX fixture we have produced so far. Monochromatic emitters like deep red are the only ones that can offer energy/yield efficiency advantages of HPS and until new developments in phosphors, blue chips or the stability of quantum dots our lights will most probably include high ratio of quality 650-660nm LED's.
Now that said the important question we faced when designing the XXXXX was whether to use blue or white supplementary LED's. From testing 460nm royal blue LED's produce the most desired results when observing a plants bio physical and bio chemical reactions to light like phototropism or the optimization of Chlorophyll A absorption by increased absorption at Chlorophyll B. Apart from those functions Royal blue really contributes very little to the growth of the plant where a white light spectrum can drive growth and photon absorption at Chlorophyll A and B. However regardless of the white LED's spectrum the efficiency of the emitter can never be as efficient as the Royal Blue LED chip alone due to the remote phosphor. So in short if we choose Royal blue we could use a lower ratio of them and a higher ration of deep red and this would be the most efficient for photosynthesis. Alternatively you can use a slightly higher ratio of white LED's in combination with a proportionally lower number of deep red. Both methods will grow plants at very similar rate per watt with the Deep red/ royal blue being the most efficient.
The big factor for XXXXX using more white LED's over Royal blue is the so that the user has the ability to safely inspect and work in the same area when he lights are turned on with out damaging their eyes. For this we look at the international electronic community standard IEC62471 and the reports companies like CREE produce
http://www.cree.com/~/media/Files/C...p/XLamp Application Notes/XLamp_EyeSafety.pdf. These show that shorter higher energy wavelengths like royal blue are the highest risk for eye safety. This is why on the XXXX we decided to go with a Deep red/far red/ royal blue/ white spectrum substituting some deep red and and most of the blue LED's for white LED's. On the new systems we will be going with Deep red/Far Red/White. The white LEDs have a custom binning but still the overall spectrum is not the most efficient we could build but it is the safest and easiest to work with. That said the new lights are still using the best quality LED's and new optical technology unique toXXX I think there will be very few products on the market in the next few years that will come close to them efficiency wise."