Calculating PPFD for a grow space with COB LED's

So I am having trouble finding legitimate sources that show me the data for efficiency of the newer gen COB lights. Vero 29 gen 7's, quantum boards, etc

To my best estimation, a Vero 29 D Gen 7 COB efficiency is approximately 1.9µmoles/s. Compare this to a common blurple at .5µmoles/s or an HPS at 1-1.5µmoles/s and it's fairly efficient.

For those that don't know, PPF stands for Photosynthetic Photon Flux, and is a measurement that determines the total amount of photosynthetically active radiation (PAR) a light gives off.

PPF = efficiency x actual wattage

So the light rack I recently designed with 9 Vero 29 D chips (total 720 watts) pulls a rough 740 watts total from the wall.

PPF = 1.9 µmoles/s x 740 watts.
PPF = 1406 µmoles/second/watt or µmoles/second/joule

PPFD is the same as PPF divided by area, or density. We use sq m for this.

So if I were to put that light rack in a 4x4 area, or a 1.486sq m footprint:

PPFD = PPF / area
PPFD = 1406 / 1.486
PPFD = 946

The math is not that complicated, but I'm looking for an efficiency chart that shows me µmoles/s for various lights driven at various wattages. For example, my Vero 29 lights are more efficient at lower power than higher power. I'm running them at 2100mA instead of the conventional 1400mA. They are 36v chips, but the higher voltage chips are also more efficient. The 1.9µmoles/s efficiency is a number I found on a commercial light rack and also I think once mentioned by growmau5, although I don't recall him getting into detail on where to find these figures. It was most probably for a higher voltage chip run at lower power for higher efficiency. So where can I find the info I'm looking for?

I'm not just interested in the Vero 29 but also the Quantum boards and all the other new tech.

Unfortunately, the information you're looking for isn't always readily available. You can find this data yourself though.

Photosynthetic Photon Flux, or PPF, is a measurement of the number of photons a light source emits per second that are within the PAR range.

Click to expand...

PPFD stands for Photosynthetic Photon Flux Density, and is the same as PPF, but takes surface area into account as well.

Click to expand...

COB efficiency is measured in (%).


Vero 29 3000K @ 2.1a x 37.6V (forward Voltage)= 78.96w x 9 = 710.64w = 37.48% Efficiency (according to the chart above)


You said you're driving your chips @ 2.1a so this is likely very close to the efficiency you're running, depending on the kelvin temperature of your COBs.


A guy who used to post here developed a Photosynthetic Spectral Quality Calculator to help us determine the figures you're looking for. You need to find the Typical Color Spectrum chart on your COB's datasheet, then digitize the spectral distribution of the spectrum you want to test (3000K, 3500K, etc.), which is showcased in that chart, using a program called WebPlotDigitizer. Once you've done that, format the data in the pre-coded excel file the developer of this calculator provided. Now you need to input the Forward Voltage (V) of your COB, Drive Current (A) you're running it @, Nominal Flux (lm), and Typical Relative Flux vs Drive Current (%), which is also a chart on the COB’s datasheet.

Some COBs have a fixed fV, like the Cree CXB3590 (36v or 72v). Some have a variable fV, like the Vero 29. If you can't find any data to help you determine the fV of your COB @ your desired output current, then you need to use a multi-meter to physically test the COB @ that drive current in order to know the corresponding fV.


Load all of this into the calculator and it will produce these figures:
QER (umol/W/s), LER (lm/W), Efficiency (%), PAR (W), PPF (umol/s).


I had already done this for the Vero SE 29 Gen 7 3000K so I can show you an example of this in action.


Vero SE 29 Gen 7 3000K @ 2.1a x 37.6fV = 78.96w || 710.64w (9 COB Fixture)



To more accurately calculate PAR, you need a Quantum Sensor. If you don't trust the COB datasheets, you'll also need a Lux Meter to collect the Nominal Flux which you can then plug into the calculator to accurately determine all of these figures.

So, if we want to trust the calculator, which is likely very close to reality, then the figures for a (9x) Vero 29 SE Gen 7 3000K Fixture would be:

PPF = 1428.651
PPFD = 961.407 (4'x4' Footprint)

The calculator produced very similar numbers to what you've posted and even the efficiency % @ that output current.