CRI, What's the deal?

[Q9550]

Hi All,

Was just wondering if anyone considers CRI ratings when building COB fixtures?

I'm currently working on setting up a new 300w LED and have been looking at a few COBs. My previous lights were 20w CXA2530s with an 80CRI. I have been reading a few forums and grows and it seems the guys are now leaning towards the 90 and 95CRI options. Apparently the higher CRI chips tend to grow a bit better although the lumen output is slightly lower, anyone got more info on the subject?

[SkunkPharm]

Colour rendering index. 100%=sun. Thus the closer 100%the better

Sent from my VTR-L09 using Tapatalk

[growopz]

The higher CRI shifts the peak red to the right, giving less green and more infrared.

Just as an example, for some CCT (colour temperature) the 80 CRI might peak in the red somewhere around 640nm, and the 90 CRI might peak in the red around 660nm.

So you have more infrared with the 90 CRI.

In some cases, especially where temperatures are low, that infrared will help raise the leaf surface temperature. But the photons with wavelength above 700nm are probably not doing much photosynthesis.

So it's a debate between that "warmth of the Sun" quality of higher CRI, and the higher PPFD of lower CRI.

 

Edited March 20, 2019 by growopz

[greenkush]

On 2/27/2019 at 4:29 PM, SkunkPharm said:

Colour rendering index. 100%=sun. Thus the closer 100%the better

Sent from my VTR-L09 using Tapatalk
 

You may want to read more into the McCree curve.

https://www.photonics.com/Articles/The_McCree_Curve_Demystified/a63340