Horti LED emitter and LED COB technology
First of all you have to understand that not every LED is the same.
These LED packages start inside from a blue LED die and convert the blue color to the green and yellow middle spectrum by using yellow and red phosphor.
A high CCT (Correlated Color Temperature) value like 5000K means less phosphor so more blue, why low CCT values like 2700K means more phosphor and less remaining blue light.
LED grow lights using many of these white LED emitters turn up with final efficacies of 1.8µmol/J to 2.1µmol/J while market leading efficacies tend towards 2.8µmol/J which means you get (compared to a 2.1µmol/J luminaire) 33% more effective micromoles for the same energy consumption.
The CCT values of a Cob can be 1/1 compared with these of single LED packages.
A typical look of a COB – starting from internal blue LED dies with phosphor cover to convert to green and yellow.
Still when you look at efficacy as leading driver this technology can’t (yet) be compared with direct wavelength emitters as explained further below.
Seoul Semiconductor Sunlike – new technology to achieve ultra-wide spectrum from single COB.
Below illustration from Osram Opto Semiconductor shows how a single LED emitter can focus exactly on that wavelength with highest plant response.
Therefore we are focusing in horticulture lighting on the 450nm, 660nm and 730nm LEDs.
All three important wavelength are available in the same LED package:
In the 660nm package at nominal drive current 350mA the efficacy goes as high as 3.91µmol/J what is nearly double from white leds.
Never the less the high efficacy you can get with this type of LED packages, you also have to take the driving current into account – the higher the driving current, the lower the efficacy gets.
|Osram Oslon Square||Wavele ngth [nm]||U typ. [V]||U hot [V]||I [A]||PPF, μmol/J|
|Hyper red Square||660||2,15||3,40||2||1,90|
So as a LED grow light designer you have to make the trade-off between maximal micromole to power efficacy by using a much higher number of LED packages (which are fairly expensive) or finding the sweet spot where price to micromole is at its highest point of return on investment.
As you don’t want more micromoles over your canopy, this 30% is pure gain on your electricity bill, from one LED grow light compared to the other one…