What's my PPFD and PAR?

Kaplow23

Kaplow23

Member
Hey guys, I have my frame and everything measured. Plan is to use x12 CXB3590 COB in a 40"x40" frame. x6 3590 at 3500k and x6 at 5000k. 2 meanwell drivers 320watts at 1.4 amps in a series of 6. It's for my grow tent which is 4'x8'. I've been searching forever and realized it's much cheaper to make your own, while getting the spread I wanted. If this one works out good I'll make a replica for the other half of my tent and have a ceiling of light! I would like this to be a seed to harvest light. All in one. Thanks guys!
 
Porky101

Porky101

Well-Known Member
Are you asking what PPFD is and what PAR IS?


I understand them to be the same. Par is the name of the radiation that the plant recieves. PPFD is more of a "live" measurement in a specific area.
 
10WeekFlushBro

10WeekFlushBro

Well-Known Member
Use DIY Cob Led Calculator (search for it).
6x3500 at 1400ma: 233ppfd in 4*8
6x5000 at 1400ma: 258ppfd
adds up to, Barely Enough, in a 4x8. You'll want to add another 320 or go for 2 480s if you want to flower a 4x8
 
Kaplow23

Kaplow23

Member
I will have 2 of these lights for my 4x8 grow tent. Each light fixture is for a 4x4 area essentially. I've tried finding a simplified version of the calculator but that formula looks a little complicated for me. I'm trying to wrap my head around how you get the PPFD calculated. Thank you for the responses so far.
 
Kaplow23

Kaplow23

Member
Sethimus sent a link over with math formulas so I thought that was the calculator. Thanks for the kind words
 
10WeekFlushBro

10WeekFlushBro

Well-Known Member
(BTW, Alternatively to achieve this increased output you can get in the ballpark running them at 2.1A, but that reduces efficacy, and won't spread as well as 2 theoretical cobs running at 1.050mA. So that's why I think your best option is to go for 18 cobs which will take a theoretical 907w at 1.4A, assuming they take 36v at that current)
 
Kaplow23

Kaplow23

Member
I'm just trying to figure out how to open the .class file now so I can dive in. Thank you! Looks like I need to revise this light
 
R

Ryante55

Well-Known Member
Kaplow23 said:
I will have 2 of these lights for my 4x8 grow tent. Each light fixture is for a 4x4 area essentially. I've tried finding a simplified version of the calculator but that formula looks a little complicated for me. I'm trying to wrap my head around how you get the PPFD calculated. Thank you for the responses so far.
Click to expand...
You don't really calculate ppfd it will vary alot par isn't a measurement I think you might be looking for ppf? Which is fixture output. then you can kinda estimate ppfd from the ppf output but you would probably be more accurate using a lux meter because at least you can see hot spots
 
Kaplow23

Kaplow23

Member
Ahhhhhh okay, I'm just trying to get ideas, I dont want to drop 1k in lights and it not be enough output.
 
coreywebster

coreywebster

Well-Known Member
Kaplow23 said:
Hey guys, I have my frame and everything measured. Plan is to use x12 CXB3590 COB in a 40"x40" frame. x6 3590 at 3500k and x6 at 5000k. 2 meanwell drivers 320watts at 1.4 amps in a series of 6. It's for my grow tent which is 4'x8'. I've been searching forever and realized it's much cheaper to make your own, while getting the spread I wanted. If this one works out good I'll make a replica for the other half of my tent and have a ceiling of light! I would like this to be a seed to harvest light. All in one. Thanks guys!
Click to expand...
This is what the cob calc gives if they were all 3500k over 4x4 space.

CXB3590CD36V3500K 12 COBS @1.4A ON 1.813 PROFILE HEATSINK
16 SQ.FT. CANOPY 94% EFFICIENT DRIVER @11 CENTS PER KWH
Total power watts at the wall: 623.4
Cobs power watts: 586
Total voltage forward: 419
Total lumens: 106968
Total PAR watts assuming 10% loss: 297
Total PPF: 1381.05
PPFD based on canopy area: 929.09
PAR watts per sq.ft.: 18.56
Cob efficiency: 56.34%
Power watts per sq.ft.: 36.63
Voltage forward per cob: 34.89
Lumens per watt: 182.54
Heatsink riser thickness / number of fins / fin's length: 0.3in/6/0.95in
Heatsink area per inch: 100.94 cm^2
Total heat watts: 256
umol/s/W / CRI: 4.65 / Estimated
Heatsink length passive cooling @120cm^2/heatwatt: 304 inches
Heatsink length active cooling @40cm^2/heatwatt: 101 inches
COB cost dollar per PAR watt: $1.92
Electric cost @12/12 in 30 days: $25.19
Electric cost @18/6 in 30 days: $37.53
Cost per cob: $47.62
Heatsink cost per inch cut: $0.66
Total cobs cost: $571
Total heatsink passive cooling cost: $201
Total heatsink active cooling cost: $66
 
Kaplow23

Kaplow23

Member
Dang, thank you for all that info. That's exactly what I was looking for. I'm going dig in tonight and try to figure out how to open that dang file. I really appreciate it guys. Thank you!
 
coreywebster

coreywebster

Well-Known Member
Kaplow23 said:
Dang, thank you for all that info. That's exactly what I was looking for. I'm going dig in tonight and try to figure out how to open that dang file. I really appreciate it guys. Thank you!
Click to expand...
That info is from the cobcalc which there is a link to in post #6.

To open it you need to have java installed. Right click and open with java.

Then you can play around with different numbers of cobs at different currents over different square footage to get rough idea of ppf and ppfd.
It may not be 100% accurate but its close enough. Im lazy so its enough for me.
 
Kaplow23

Kaplow23

Member
coreywebster said:
This is what the cob calc gives if they were all 3500k over 4x4 space.

CXB3590CD36V3500K 12 COBS @1.4A ON 1.813 PROFILE HEATSINK
16 SQ.FT. CANOPY 94% EFFICIENT DRIVER @11 CENTS PER KWH
Total power watts at the wall: 623.4
Cobs power watts: 586
Total voltage forward: 419
Total lumens: 106968
Total PAR watts assuming 10% loss: 297
Total PPF: 1381.05
PPFD based on canopy area: 929.09
PAR watts per sq.ft.: 18.56
Cob efficiency: 56.34%
Power watts per sq.ft.: 36.63
Voltage forward per cob: 34.89
Lumens per watt: 182.54
Heatsink riser thickness / number of fins / fin's length: 0.3in/6/0.95in
Heatsink area per inch: 100.94 cm^2
Total heat watts: 256
umol/s/W / CRI: 4.65 / Estimated
Heatsink length passive cooling @120cm^2/heatwatt: 304 inches
Heatsink length active cooling @40cm^2/heatwatt: 101 inches
COB cost dollar per PAR watt: $1.92
Electric cost @12/12 in 30 days: $25.19
Electric cost @18/6 in 30 days: $37.53
Cost per cob: $47.62
Heatsink cost per inch cut: $0.66
Total cobs cost: $571
Total heatsink passive cooling cost: $201
Total heatsink active cooling cost: $66
Click to expand...
awesome, been playing around with the calculator now that I have it working properly. Seems to me these numbers above are good?? I want PLENTLY of light for flower. 929 seems on the high end right? why is there not an option for watts? how do watts come into play? Should I stick to the 220 watt meanwell or jump up to 480? I will have 2 drivers with 6 cobbs each
 
coreywebster

coreywebster

Well-Known Member
Kaplow23 said:
awesome, been playing around with the calculator now that I have it working properly. Seems to me these numbers above are good?? I want PLENTLY of light for flower. 929 seems on the high end right? why is there not an option for watts? how do watts come into play? Should I stick to the 220 watt meanwell or jump up to 480? I will have 2 drivers with 6 cobbs each
Click to expand...
The watts are dictated by the voltage of the cob multiplied by the current you put through it.
The driver selection has to be based around the amount of voltage the driver can supply as well as the wattage and current.
For that you need to look a the data sheets of the driver.
The cob changes voltage slightly at different currents, the harder you push it the more voltage, which also can be seen on the cob data sheet but having the cobcalculator is useful for that too.

Because your looking at just over 600w between two drivers you cant use the meanwell 240h
but you could use the meanwell 320h-c1400 driver which has range of 114-229v and using that on 6 cobs running at 1.4amps gives a voltage of 209v which falls in that range. Its a 320w driver and those cobs also fall in that range too coming in at 311.7w at the wall.

https://www.meanwell-web.com/content/files/pdfs/productPdfs/MW/HLG-320H-C/HLG-320H-C-spec.pdf


That's assuming im right in thinking your going to run 12 cobs between two drivers per 4x4 space?
 
Kaplow23

Kaplow23

Member
Yeah that's correct, 12 cobs - 2 drivers - 4x4 space. I'm starting to wrapvmy head around all this thank you a bunch. If my understanding is correct, watts = yield (predominantly) correct? I may be thinking of using 480watt/1.4 amp if my thinking is correct to increase yield.
 
coreywebster

coreywebster

Well-Known Member
Kaplow23 said:
Yeah that's correct, 12 cobs - 2 drivers - 4x4 space. I'm starting to wrapvmy head around all this thank you a bunch. If my understanding is correct, watts = yield (predominantly) correct? I may be thinking of using 480watt/1.4 amp if my thinking is correct to increase yield.
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To a point more light is good. But these are strong lights and after a point it can be detrimental or at least not beneficial without changing other factors like increasing co2 levels and with that comes raising temps more.

You could grow with 480w per 4x4 but I think your saying 2x 480w drivers instead of the two 320w drivers I suggested.
IMO that would be too much and not only that but powering 6 cobs on a 480w driver at 1.4amps would not give you more power, you would have to up the current to 2.1amps to hit that, technically it would work on a 480h-c2100
but then you also need to increase your heat sink size to counter the extra power and because your running them harder its less efficient, you would be hitting over 1200ppfd and that I think is too much without co2. Which is never ideal if in a tent as it gets vented out.

If it were me I would be very happy with 620w of power and the 900+ppfd per 4x4.

There have been test on here and other forums showing the point at which the increase in light becomes pointless.
I just cant remember the results or what the threads were called.

Throwing more light at something doesn't always increase yield and learning a strain and training and keeping a plant healthy will give far more benefit than having a shit load of light and badly managed space and plants.
 
Porky101

Porky101

Well-Known Member
coreywebster said:
To a point more light is good. But these are strong lights and after a point it can be detrimental or at least not beneficial without changing other factors like increasing co2 levels and with that comes raising temps more.

You could grow with 480w per 4x4 but I think your saying 2x 480w drivers instead of the two 320w drivers I suggested.
IMO that would be too much and not only that but powering 6 cobs on a 480w driver at 1.4amps would not give you more power, you would have to up the current to 2.1amps to hit that, technically it would work on a 480h-c2100
but then you also need to increase your heat sink size to counter the extra power and because your running them harder its less efficient, you would be hitting over 1200ppfd and that I think is too much without co2. Which is never ideal if in a tent as it gets vented out.

If it were me I would be very happy with 620w of power and the 900+ppfd per 4x4.

There have been test on here and other forums showing the point at which the increase in light becomes pointless.
I just cant remember the results or what the threads were called.

Throwing more light at something doesn't always increase yield and learning a strain and training and keeping a plant healthy will give far more benefit than having a shit load of light and badly managed space and plants.
Click to expand...


I have had grows where the lowers buds are just as fat than the top buds, and they were recieving a lot less light.

Aslong as your 500+ umols(low end, 900 top end), the rest is the environment, feedings etc. I believe.
 
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