While there are still legitimate applications for using HID bulbs, the advantages of using COB LED grow lights outweigh the disadvantages. Can this technology justify the cost? The initial introductory price for using COB LEDs in indoor gardens is high, but they will pay off in the long run because of the multiple advantages.
I will freely compare COB LEDs to the most commonly used high-quality lighting today, namely: HPS, CMH, and MH lighting.
This is an example of the spectrum you can find in most high-quality COB LEDs. Note that while there is always variation between companies, most cases are the same. Any manufacturer offering a 3500K 90CRI COB should be closely matched to any other 3500K 90CRI COB of the same voltage rating.
Full Spectrum COB LED Growth Light
One of the main reasons COB LED plants to grow lights are making their way into many grow rooms so quickly is because of their high color rendering index (often over 80) and broad-spectrum.
CRI stands for "color rendering index" and describes how the color of the light source changes the appearance of the object to the human eye and how it reveals subtle changes in hue.
Regardless of the COB manufacturer, they all offer at least 70 CRI broadband spectral chips, often up to 97 CRI. This means no violet, extreme orange, red or yellow, but high-quality white light that displays realistic colors.
Until now, LEDs were an option for those who needed low power consumption. Until now, LEDs have been much more efficient at producing photons than any HID technology. This means that a high-quality COB LED will outperform HID technology in providing high-quality lighting for the canopy at the same power consumption.
Both HID and COB is single-point light sources. However, because COBs are relatively easy to handle and position, we have a very different situation. Instead of using a single light source, the COB LEDs can be spaced out to achieve better uniformity, thus avoiding hot spots or low-intensity areas within the growth chamber.
A practical example is that instead of having a large 600W HID luminaire that causes hot spots, we can have 6 COB LEDs producing the same amount of light while consuming less light and providing a better diffusion approach.
A 500-watt luminaire will produce 500 watts of heat. Whether it's HID, CFL, or LED. the common misconception is that a 500 watt LED is less than a 500 watt HID, and while this is usually true, it's not for the reasons people think about.
The reason is mainly infrared radiation. Far infrared is radiant heat, which is the same as the warmth you feel from the sun on your face and the heat you get from burning coal. It is even the heat your own body gives off. LEDs (unless specifically designed to do so) rarely produce infrared light, and now compare the spectrum to HPS and you will soon understand why HPS lights are always so hot.