Building LED panel to grow leafy veggies what and were to start help needed

Brand new at this and found this forum and just joined. I have read some awesome stuff about LED's and want to know if this is a viable solution to T5 lights or not.
I am growing veges all of which are baby lettuce and herbs just growing them to maybe 2 or 3 weeks old. No flowering so just leaf production.
I am growing in a 30" wide x 10 foot space vertically and will have 2 or 3 shelf's on top of one in other. I will probably have between 18" and 24" between each shelf. I was looking at using 2 T5 units to cover the shelf below and 2 T5 units above.

Reading here about LED panels and lights and seeing Chinese made stuff I came to the conclusion that I could make something a lot better and hopefully it will not be more than the T5 stuff. I was thinking about building my own panels and thought that I would use 4 LED panels over the top of a 30" x 30" square or build strip panels to cover the whole area 30" x10 feet or do 30" x 5 feet. I was looking at using mostly the royal blue stars from CRE with some red mixed in if I needed it or white.

With the cost of T5 panels at $99.00 for a 4 tube 4 feet long is it possible to make something for less in LED panels my self? Is the LED panel with the correct color LED going to give me the same results in the growth? Has anyone here done any tests using an LED next to a T5 to see what the results were? How do you figure LED spacing for my growing area?

I have made several things for my PC and can solder but need to know where to start and find some tutorials on making these. How I can use drivers to manage as many panels as possible safely. Where are some good places to get parts reasonably?

Thanks in advance to anyone that can help me.

You can get a 4x48" T5 HO fixture for about $100 now, if not a bit less if you shop around (standard T5's in a 2x arrangement don't seem like enough PAR in my opnion). Nothing in LED land is going to provide anywhere near the growth levels for the price of a T5 HO shop light. You can also swap bulbs in a T5 fixture and go from vegetative (mostly blue or cool white light) to stimulate stem growth (mostly warm light) by popping out and changing a couple $5 bulbs. With LED fixtures you're money is tied up in one color, or another.

That said, I use my own LED fixtures I build because I know what color orientation I need before building, and I don't have to fuss with deteriorating bulb out-put. Efficiency is also on the side of LED's and increasing steadily as tech improves while fluorescent technology has leveled off long ago. See the thread in the fixed lighting forum I just made about the fortimo units to see just how bad fluorescent compares to increasingly higher end LED units. The fortimo modules were so easy to work with I coulnd't be forced to going to soldering dozens of cool-white stars unless the efficiency gap really gets extreme, and right now it's not.

As for colors, I'm not convinced royals do anything better than the same tech level of cool white, except the royals are 10x harder on your eyes and in my experience don't seem as robust for vegetative growth. Stephen L has lot more experience with lettuce requirements and will likely have some better first had advice.

I was wondering if I were then to use the standard fluorescent bulb instead of a T5? I would still use a 4 tube fixture that would be $40 less and bulbs would be $3.00 less. I am only wanting vegetative growth. Would standard fluorescent bulbs be the way to go then?

I assume by standard fluorescent tube you are referring to common T8's. T5's and T8's throw about the same lumens per watt except T5's being skinnier the are able to throw more light out of the fixture.

A standard 4x48" fixture would have to be parked lower over the plants to get the same intensity and left on longer.

I took a look at the fortimo modules this weekend and like the way they work but what do they cost and what could 1 strip cover exactly in space below?

I also looked at all kinds of DIY sites, ideas and other panels. I found this panel - Sunshine systems glowpanel 45 28w LEDGP45 and many use it to grow a lot of things. It looked like it was best used to be in the early vegetative stages which is what I am looking for. It also looked like it would cover a 30" x 30" space below so I would need 4 of them to cover my 30" x 10 foot area. I want to have 3 30" x 10 foot growing trays giving me a total of 12 units. I have seen them sell for $110 to $150 in the US and if you purchase from China about $76 for 12 plus $96 for shipping getting them to about $84 each.

Then I did a spreadsheet on using 4 foot 4 bulb T5's versus the LED growpanels.

Using 6 T5 units to cover the 30" x 10' space versus 12 LED panels for the panel and bulb costs were..
T5 = $744 versus LED = $1008.
The LED would be $264 more

Then I did a kilowatt comparison for the power on both units.
1 T5' panel with 4 tubes use 260 watts and glowpanel will use 28 watts.
The monthly cost for me on each fixture then would be..
T5 = $89.85 versus LED $19.35

The monthly savings would be $70.50 on the LED's. It would take 3.74 months of use on the LED electrical savings to break even and then from that point you would be saving $70.50 each month.

If I have figured something wrong please let me know but that looks pretty good.

Some of the disadvantages are..
1. I am buying a product from China and if there are any warranty problems it may be hard to deal with them.
2. How long will the panel really last?
3. When LED's burn out can't replace them.

If I want to build the 12 panels myself using white CRE's in order to get 27 watts that would be 9 3 watt LED's. The cost of CRE's I found were about $2.50 each(anyone find them cheaper please share) that put the panel at $22.50. I need a heatsink, driver, wire and odds & ends.
1. Would this DIY build be the same as the Growpanel 45?
2. Would I get the same amount of light or would it be higher or lower?
3. Could I cover the same space?

Because I want to cover a 30" x 10 foot space could I build a group of 4 heatsinks using 9 LED in each with 1 driver running them all?

All I know is the growpanel 45 works for growing many things from the forums and posts I have read and for this application should be okay. There are some specs on it but becasue I do not know that much about the actual bulb they have in it I do not know enough to be able to compare it to the CRE line and build something that would be close in apples to apples and then get a cost comparison.

Your thoughts?

If you think that the amount of 28W LED light can compare to 260W T5 light, you are very very wrong. Just check the lumen numbers. 260W of T5 bulbs will give you about 24000 lm . So let's take Crees XB-D for example. The blue one produces 92lm @1A and the red one produces 210lm @1A. Vf of blue is about 3.5V @1A so that's 3.5W. Vf of red is 2.5V so that's 2.5W. If you take the 6:1 ratio for red:blue that would give you approx 1700lm of red and blue light at power consumption of 28W. But The panel consumes 28W itself. So let's say the driver is 85% efficient that would give 1700lmx0.85=1450lm. T5 also produces other colours that are counted in those 24000lm so you would come close with about 180-200W red and blue LED light.

Thanks Toaster79 for this info. So then with what you are saying would I need to have an LED panel at the 260 wattage to get the same growth? I thought that using LED's for growing had the advantage of using less wattage with similar results. I thought that comparing lumen numbers did not have to be the same when comparing LED's panels.

What size panel then would be the same as a T5 panel @ 260watts?

Confused

Plants do not grow based on lumens. I think some of you are stating generally correct things, but not quite grokking what a lumen really is. Radiant flux is a measure of how many photons come from a source of light. You might even narrow your query to 'How bright is this light' to visible light. But the human eye does not perceive all visible light equally, so the lumen was created, taking into account these differences. The short version is: To grow a square meter of plants (As big as my kitchen table) takes a LOT of light. I would guess 100W of high-quality LED might do for moderate-light plants. This is extrapolating up from my aquarium.

Plants have, broadly speaking, three types of light-consuming chemicals. They do not use all wavelengths equally, so a unit called Photosynthetically active Radiation was created. Those three chemicals have varying 'activity curves' when charted next to wavelength of light. In theory, a "perfect" light source for plants would only output the wavelengths needed for plant growth. In practice, this is tough.

What wavelengths do plants need? Some say that leafy things only really need blue...but the leaves may become extra-dark and glossy than is normal. Some say that red improves flowering and fruiting, others that seedlings only need blue lights. But all of this is oversimplifying. Colored LEDs have varying frequencies, so one man's "red LED test" may fall in a valley of the PAR curve for his plant, while another man's "red LED test" lands on a local maximum and "invalidates" the first study. I find that plants grow just fine under neutral-white lights, and look much nicer than under blue/red mixes.

How do you most-efficiently make the frequencies you choose? This will depend on what you've chosen. You're going to need a LOT of light. Aquarists and coral reef growers are about the most science-minded people I've found online who frequently talk about their grow lights and experiences. Try them out. They generally suggest darn bright lights, and like T5s over T8 for higher source intensity. Does that matter? Maybe.

Edit: I forgot to mention: A fluorescent-tube fixture will throw away about 1/3 of the lumens. Many are matte-white on the bulb backing, with close bulb spacing and a diffuser. Improving the reflector helps a lot with light extraction, but don't count your lumens before they hit your plants.

Like i said around 180-200W should do. But then again, went reading through the thread again and see you need light for vegging only, so that means you could pull it off with cool white LEDs. So according to datasheet the efficiency of XM-L U2 is 150lm/w when driven at 700mA that's 300lm at 700mA meaning you would need about 80 pieces to cover the 260W T5. In this case the numbers are in favor of the LED consuming 160W against 260W. XM-L driven at 2A would produce 742lm so you would need 32 pieces but the power consumption would be around 215W.

@AnAppleSnail: I'm just trying to illustrate that 28W LED light can't replace 260W T5 fixture, but 200W LED light might. Color mixing is matter of plant you grow, that's clear to me. And putting some blue and red LEDs doesn't mean you've got the color spectrum covered. Putting together right mixture of different wavelengths of royal blue, blue, orange-red, red, deep red and far red does, but it all depends on whether you grow lettuce, tomatoes or pot.

Some people are actually reporting good results growing under LEDs: https://www.thcfarmer.com/community/threads/led-grow-lights-for-micro-grows.48789/

Toaster79 said:

Some people are actually reporting good results growing under LEDs: https://www.thcfarmer.com/community/threads/led-grow-lights-for-micro-grows.48789/

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I get good results in my aquariums from LED and fluorescent both. It just takes a lot of light either way. Note: Might want to mark that as a NSFW link, since it's weed growing.

Weed growing is not illegal in some countries so ....

@toaster79 I am growing leafy greens and only need them to grow for 2 weeks and then they get harvested so they will never need to flower ever. So the cool white idea could work but I was only asking about the 28 watt panel because people are using them to grow pot and getting mostly good feedback in the early vegging stages and that is all I want to do. To build a 32 piece panel and then having it at 215 watts does not save the 30% to 50% that everyone is saying they get. I have to believe that I could get away with way less.

@anapplesnail Your results with growing in the aquariums with LED.. Does the water have any effect on the light transmission to the plants? If yes then maybe growing leafy greens with LED's may work even better.

I will have to purchase a T5 fixture then along with the 28w panel and grow something exactly the same in both and test it. I will have a 3rd test at the same time in the sun and see how all 3 do. I can't grow in my greenhouse without a ton of heat in the night so that is why I am trying to see what can be done if anything at a reasonable cost.

Plants do not grow based on lumens.

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True, but we're using lumens as a reference for relative light performance. The next 'discussion' is if the spectral slope of your typical white LED is more efficient for plant growth because it's broader in the active growth regions -vs- coincidental spikes of fluorescent and HID. However, lumens at the moment is all we have to work with given we aren't all carrying PAR meters (which I don't trust anyways because they just read purple intensity).

I find that plants grow just fine under neutral-white lights, and look much nicer than under blue/red mixes.

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Same here. Blue / purple LEDs drive you batty after awhile, and there's little difference in royal blue emission between a cool-white LED and a royal in the same tech class. White light also seems to produce more even growth. Red however is a different story and red only LEDs do produce more 625nm energy than warm-whites. 660-670nm Rebels a LOT more. Is it worth using these over lets say warm-white XM-L's?.....I dunno. Very little research on this.

I have noticed that longer wavelength blue in the 465-475 region does cause different reactions in most terrestrial plants and especially corals. Growth seems much better with 465-475 in terrestrials over royals while corals are very sensitive to bleaching in this wavelength. Frankly I've found royal blue only light doesn't do much at all for various houseplants and such. Seen conflicting tests for veggies.

In this case the numbers are in favor of the LED consuming 160W against 260W.

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It's actually much worse for the T5 fixture. Whatever wattage a T5 fixture is I will assume half the wattage of XM-L's are needed. The Fortimo fixtures I was testing are only about 118 lumens per watt, and they wreak T8's at half the wattage. T5 fixtures (not bulbs) are typically more efficient than T8 because there's less strikeback, but not THAT much more efficient.

Assume you need 2/3 the wattage of XM-Ls to match the Chinese panel. In fact, that's probably optimistic for the panel. However, given the price why not go ahead and test one.

One thing that's missing here is coverage. A big reason fluorescent is still so popular for hobbiests is they spread out a lot of light over a wide area, and this is more efficient for plants to grow under than super intense point light sources. You could slap half a dozen Bridgelux on a big sink with a 120mm fan for cheap and be visible from low orbit, but the effective growth energy just blasts specific areas of the plant and is less effective than lower energy light sources that are more distributed. Been there - done that. This is why I'm sticking to long rails. Yes, the sun is a point light source, but the sun also traverses the sky from morning to dusk. Corals are entirely different and do much better under point light sources like halide and really only care about blue light.

I just wonder if most of these set-ups will actually provide enough light to do the trick. It might work well for what the OP is doing because he's growing very short plants that wont ever get tall and wont be growing very long. But I went out 8 years ago, before I was even aware of LED grow light technology and I bought a 400W professional HID grow light fixture and a 400W metal halide grow bulb to keep my many tropical and warm climate plants alive til spring when I could move them back outside like I did every year til early November.

So the other problem was that my house was aligned in such a way that the sun came across the right side of it, and didnt get through the front windows for long, and the back windows were partially covered by the large covered porch out back, which prevented direct sunlight into the back windows, except for my office with its one rear window. So I didnt have any real natural sunlight coming in, certainly not enough for the plants, and there wasnt enough room for them upstairs because there were many of them, so I had to set up in the basement which had only 2 small windows and was very dark and very dry in winter. Ironically it was very humid in summer, which forced me to move my then-new drum set upstairs to the loft because there were tiny spots of surface rust forming on the chromed hoops after just a couple months!

I set up the 400W halide fixture, and a 120v grow light, and 2, 2-bulb fluorescent fixtures in the basement, but even that wasnt enough, and they would start losing leaves within a few weeks usually! Most wouldnt die out, but the citrus plants wouldn't ever flower properly and didnt produce fruit, even though I put a flowering spectrum type incandescent bulb over them as well. and they ended up losing most of their leaves, which wouldnt grow back til I moved them back outside the following spring/summer. Many of these plants were 4-5 feet tall, so they didnt get much light to the mid and lower leaves. Some plants did die too. The only plants that did half well were the shorter ones on my table down there that had a fluorescent fixture right over top of them.

Bottom line, they just werent getting enough light, but the other problem was the dry air as well(That shouldnt be a problem for lettuce though)

I finally gave away a few of the Agaves that didnt die, and the only other plant I still have left from then is a Pomegranate bush that I grew from a seed from a pomegranate from the grocery store. Oh yeah, I also gave away a couple banana plants as well.

@toaster79 I am growing leafy greens and only need them to grow for 2 weeks and then they get harvested so they will never need to flower ever. So the cool white idea could work but I was only asking about the 28 watt panel because people are using them to grow pot and getting mostly good feedback in the early vegging stages and that is all I want to do. To build a 32 piece panel and then having it at 215 watts does not save the 30% to 50% that everyone is saying they get. I have to believe that I could get away with way less.

@anapplesnail Your results with growing in the aquariums with LED.. Does the water have any effect on the light transmission to the plants? If yes then maybe growing leafy greens with LED's may work even better.

I will have to purchase a T5 fixture then along with the 28w panel and grow something exactly the same in both and test it. I will have a 3rd test at the same time in the sun and see how all 3 do. I can't grow in my greenhouse without a ton of heat in the night so that is why I am trying to see what can be done if anything at a reasonable cost.

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I have been doing R&D for the last 2 years growing Baby Leaf Lettuce in a controlled environment using LED based lights as the only source of illumination.
Blasterman is correct that a T5 setup is the most effective solution from a first cost basis.

You need to understand the wall plug efficiencies(WPE) of the various light sources available to you. In your specific case we need to compare T5 Fluorescent to LEDs. Obviously the WPEs of T5 Fluorescent and LEDS vary greatly but I will try to present a best case scenario for both technologies.

T5 Fuorescent High Output
4000K
High Efficiency Ballast 95% efficient
Bulb HO >100 lumens per watt - 30% efficient
Reflector 85% efficient
Housing 95% efficient
-------------------------
30 x .95 x .85 x .95 = 23% WPE

LED
4000K
High Efficiency Power Supply 90% efficient
LED Output >120 lumens per watt - 36% efficient
Reflector NONE
Housing 95% efficient
-------------------------
36 x .90 x .95 = 30% WPE

In summary - the LED system outputs roughly 30% more light than the T5 system.

But we want to grow plants so we must look at the radiant flux in terms of its efficiency in driving photosynthesis. To do this we restrict the output to a range of 400 - 700 nm. Since Fluorescent is a UV based source - there is a small but measurable output below 400nm. We therefore need to derate our original T5 Fluorescent 23% WPE value by a further 10%. Similiar derating is not required for the LED source.

The final variable in these WPE calculations is the T5 Housing/Reflector. In a soil or soiless mix based program - dust is a major factor. You would need to clean the reflector daily to even come close to the derating values applied to these calculations.

Finally, for reference, all of the Chinese and non Brand name Grow lights I have tested show a WPE below 20%. Philips have some expensive professional Grower LED systems that have a value closer to 30% WPE.

Back to your original question - yes - watt for watt, you can easily use 30-50% less power for an LED based system compared to a T5 system.
But how many LED system watts do you require to grow Lettuce within a 1 square meter layout, assuming a 30% WPE?

Well, here is where it gets a bit complicated. I would suggest you read the "growing" related threads I have participated in here on CPF over the last two years. What follows is a condensed version of the conversion process of radiant flux to PAR(PPFD).

LED 4000K
30% WPE
100 source watts

100 Source Watts x .30 WPE = 30 Optical Watts Out
30 watts x 4.5 umoles per watt = 135 PPFD

Plants do not grow based on instantaneous flux(PPFD) but rather by the total amount of light received over one day - Daily Light Integral(DLI).
Commercial Lettuce growers aim for a DLI of between 12 - 18 mol m2 d-1. To calculate DLI we do the following:

(Based on lighting 16 hours per day)
135 PPFD x 16 hours per day x 60 secs/min x 60 mins/hr /1,000,000
= 7.78 Daily Light Integral

Since we want to fall between the DLI range of 12 -18 we would need a minimum of 200 source watts of LEDs at a 30% WPE. Or you can reduce the source watts and light for 20 hours per day.

If you want to grow your lettuce at a max rate I would suggest the following parameters for your system-based on a one square meter layout:
Temp 25-30C
Humidity 75%
500 source watts of LED at 30% WPE
Lighting cycle = 20 hours per day

Our R&D setup is currently running:
Temp 30C
Humidity 75%
650 Source watts at 20% WPE
Lighting Cycle = 20 hours per day

We are using BR30 bulbs as they are the lowest first cost available and allow us the flexability to continually try out different color temps and take advantage of more efficient bulbs as they become available.

slebans said:

I have been doing R&D for the last 2 years growing Baby Leaf Lettuce in a controlled environment using LED based lights as the only source of illumination.

Since we want to fall between the DLI range of 12 -18 we would need a minimum of 200 source watts of LEDs at a 30% WPE. Or you can reduce the source watts and light for 20 hours per day.

If you want to grow your lettuce at a max rate I would suggest the following parameters for your system-based on a one square meter layout:
Temp 25-30C
Humidity 75%
500 source watts of LED at 30% WPE
Lighting cycle = 20 hours per day

Our R&D setup is currently running:
Temp 30C
Humidity 75%
650 Source watts at 20% WPE
Lighting Cycle = 20 hours per day

We are using BR30 bulbs as they are the lowest first cost available and allow us the flexability to continually try out different color temps and take advantage of more efficient bulbs as they become available.

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This is great work that you are doing. What do you want from your research? There are applications on Earth and in space systems for closed-box growing of plants that you surely know more about than I do.

What do you want from your research? There are applications on Earth and in space systems for closed-box growing of plants that you surely know more about than I do.

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With our current cost structure - we need a yield of 7000 - 8000 grams per square meter of marketable fresh leaf biomass within a growing cycle of 22 days. This would allow the company to be profitable and undercut the current market pricing. We are almost there.

The challenge is one of scale. A 5,000 sq foot warehouse, with 5 levels of production, could produce enough packaged baby lettuce for a population of 2 million people. In my specific instance/location, that would require 100% of the local market - simply not practical or desirable. Either we build smaller or diversify production - that is the challenge I am currently working through before we move to full scale production.

I would recomend you the Makersled Kit in sale in ledsupply.com everything you need, just add the Leds and drivers,