LED lighting experiences.

[Trakar]

Well, HPS is already very energy efficient compared to incandescent, and in this type environment, the heat byproducts often can't be used so they have to be vented. That means more air cycles per hour, and that means jacking up the co2 level several multiples.

LED does have advantages, but it's extremely expensive compared to HPS. HPS can be found on craigslist or ebay for 10-20$ each.

Long considered out of reach for LED grow lights, large scale commercial Medical Marijuana operations are now making the switch from HID.

Commercial Medical Marijuana Operations
http://www.youtube.com/watch?v=xm8vgHznTkg&feature=player_embedded#!

LED Wholesalers 2501mx Blue Red 225 13 8 Watt Square Grow Light Panel
$22 online
http://www.amazon.com/LED-Wholesalers-2501MX-Square-Light/dp/B001MVWYZA

 

[bit_pattern]

Long considered out of reach for LED grow lights, large scale commercial Medical Marijuana operations are now making the switch from HID.

Commercial Medical Marijuana Operations
http://www.youtube.com/watch?v=xm8vgHznTkg&feature=player_embedded#!

LED Wholesalers 2501mx Blue Red 225 13 8 Watt Square Grow Light Panel
$22 online
http://www.amazon.com/LED-Wholesalers-2501MX-Square-Light/dp/B001MVWYZA

Now I just need a solar kit and I can can have carbon neutral hydroponics. Ethical!

 

[Trakar]

Now I just need a solar kit and I can can have carbon neutral hydroponics. Ethical!

"Righteous"

 

[bit_pattern]

I was discussing them with a grower today and he was very dismissive, reckons the only people who claim to have ever got a successful harvest using them are in marketing videos. Apparently the penetration of the spectrum isn't deep enough? Something like that at any rate.

 

[Trakar]

I was discussing them with a grower today and he was very dismissive, reckons the only people who claim to have ever got a successful harvest using them are in marketing videos. Apparently the penetration of the spectrum isn't deep enough? Something like that at any rate.

How much actual hands-on experience with LED set ups has this grower had?

I, personally, have only heard positive reviews, aside from the occassional closet hobbiest whose problem most likely wasn't the lighting to begin with, but then, I'm not a grower myself, so I'm only relying on what I've read and on anecdotal word of mouth. My sample size is neither large, nor probably cross-sectionally representative.

If he has an opinion or consideration that goes beyond vague impressions, I'd be very interested in hearing what they are, because frankly, most of what I've heard sounds much like the pablum that surrounds most fads.

I have however also read a few reports like these which seem to support the "marketing videos:"

"USING OF LED LIGHTING TECHNOLOGIES TO SUBSTITUTE TRADITIONAL LIGHTING SYSTEMS IN GREENHOUSES"
http://wip.sggw.pl/wp-content/uploads/energetic.pdf#page=93

"LED as light source for baby leaves production in an environmental controlled chamber"
http://bmte.niu.edu.tw/files/writing/547_8c0caa81.pdf

"PLANT-GROWTH LIGHTING FOR SPACE LIFE SUPPORT: A REVIEW"
http://gravitationalandspacebiology.org/index.php/journal/article/download/2/2

 

[bit_pattern]

From what I can tell they work very well for vegetative growth but not for the final flowering cycle. It's not a perfect solution but it does offer a good two months of considerably reduced electricity costs.

 

[WildCat]

I'm growing vegetables indoors using LED lights. I'm in the midst of my first attempt -- tomatoes, peppers and basil. I was setback by a bug infestation.

I think metal halide or high pressure sodium lights give you more lumens per watt of power, and certainly more per unit of currency.

 

[Steve001]

Another option for general lighting applications and for horticulture is fluorescent induction lighting. Life time operation of this type of bulb is equivalent to led.

 

[mhaze]

good chart comparing lumens/watt for all lighting types

http://en.wikipedia.org/wiki/Luminous_efficacy

comments and charts by a supplier

http://www.littlegreenhouse.com/guide3.shtml

Short story: LED might have some advantages for some applications - one that comes to mind is that the fixture might be water proof and hence not need the water proof enclosure - but it's not going to have marked ADVANTAGES compared to existing products used in this market area.

The greenhouse I'm building will use the T5 high intensity bulbs. Industrial and commercial lighting has been highly efficient for decades. It's interesting that consumer lighting is an area which traditionally and by comparison has not been highly efficient.

 

[varwoche]

I was discussing them with a grower today and he was very dismissive, reckons the only people who claim to have ever got a successful harvest using them are in marketing videos. Apparently the penetration of the spectrum isn't deep enough? Something like that at any rate.

The entire industry has been dismissive, and I suspect it has a lot to do with being invested in the old technology, and that the first generation LED grow lights didn't cut it at all. But LED has improved since then.

Supposedly, in terms of electricity cost, LED wins hands down. In terms of yield by area, the old technology outperforms LED. If growing for personal use, a closet will yield more than enough using LED.

 

[bit_pattern]

Supposedly, in terms of electricity cost, LED wins hands down. In terms of yield by area, the old technology outperforms LED. If growing for personal use, a closet will yield more than enough using LED.

Do you mean that they perform better in smaller areas? That certainly would make sense.

 

[varwoche]

Do you mean that they perform better in smaller areas? That certainly would make sense.

No, I mean that that LED yields less per sq ft, period, but that it doesn't matter to someone growing for personal use because the LED yield is still more than adequate. And it will cost a lot less electricity.

 

[tyr_13]

I think that once people get out of the mindset of having a few fixtures that the old incandescent forced us into and start exploring other lighting layouts, LEDs will really start to take off. I'm currently experimenting with LED bar and rope placement.

 

[mhaze]

No, I mean that that LED yields less per sq ft, period, but that it doesn't matter to someone growing for personal use because the LED yield is still more than adequate. And it will cost a lot less electricity.

I think this is wrong. Most of the setups have the light about 2' above the plants, so we are talking quite a bit of light per square foot of cultivated area.

The LED will not cost less per delivered lumen. Somewhat more than HPS, perhaps double compared to HID. Both HPS and HID, basically at salvage prices on Craigslist or ebay. So cheap it isn't even worth paying for shipping. The LED has a "cool high tech" feature granted, but both purchase price and operating cost will both be higher.

I've got some surplus HID but am going to use T5 mainly because of the size and form factor. The HID fixtures are massive, while the T5 isn't. But both are okay.

I might go for some LED just for the gee whiz cool factor. I'm not growing weed, so don't have to hide this stuff, and one factor is the appearance of a strange glow at the side of the house at night. Would the strange glow be more interesting if from LED?

 

[roger]

Let's put it this way: find me a peer reviewed article comparing LED to HID.

I'll wait......

By itself the lack of anything like that is of course not proof. But, it sure is suggestive. The free online magazine Maximum Yield has been touting LED about every month for the last couple of years yet they have yet to produce any side by side studies. Readers write in "where are the studies". You get a lot of hemming and hawing. They are coming Real Soon Now.

The behavior of growers performing illegal acts is not convincing. Their profit margins are off the charts, and can afford to do things to reduce their crime detection footprint. People like me, who do not grow illegal substances, need to look to the science. I have yet to see an article that didn't read like breathless ad copy. When Howard Resh starts writing about LED as being better than HID, I'll start listening. Until then, it's MH and HPS for me.


edit: for example, here's a link for a well regarded LED grow light being used at NASA: https://www.facebook.com/media/set/?set=a.169375066457203.42346.151110068283703 On the face of it, it is quite compelling. But, NASA is replacing a few thousand $ of HID lights for $10,0000 worth of LED lights. At my energy rates, it would take 3 years for those LED lights to break even. Plus, this is a chamber specifically designed for high light experiments - they have constraints that a greenhouse doesn't. And, of course, there is no grow data yet, just "hey, we are saving watts and heat". I regard it as interesting, but I'm not going to run out and drop a few thousand K on lights with no real data yet. Given that LED grow lights have been touted since 2008 or so, and we still have no data, color me somewhat skeptical. I have no doubt they have use in very specialized circumstances like NASA experiments, or in law enforcement evasion, but to grow my Hatch chili plants, basil and such? Naw. Not yet.

 

[Dan O.]

Comparing the luminous efficiency of lighting used to promote plant growth seems a bit strange. Why would a plant respond to the same spectrum as the human eye?

In fact, plants appear to need an inverted spectrum from what we see. There are two bands of light that plants absorb and these are above and below the visible spectrum. There might even be an advantage to using pulsed light.

 

[Trakar]

...Supposedly, in terms of electricity cost, LED wins hands down. In terms of yield by area, the old technology outperforms LED. If growing for personal use, a closet will yield more than enough using LED.

Got reference?

The links offered previously and herein seem to suggest otherwise:

LED Application Series: Outdoor Area Lighting - http://apps1.eere.energy.gov/buildings/publications/pdfs/alliances/outdoor_area_lighting.pdf

In the light of new greenhouse technologies: 1. Plant-mediated effects of artificial lighting on arthropods and tritrophic interactions - http://viken.lr.no/media/ring/1212/...on arthropods and tritrophic interactions.pdf

High-brightness LEDs—Energy efficient lighting sources and their potential in indoor plant cultivation - http://www.sciencedirect.com/science/article/pii/S1364032109000471

Approaches for Mitigating the Environmental Impact of Greenhouse Horticulture
http://pub.epsilon.slu.se/2408/1/Bergstrand_KJ__101116.pdf

Now, it may well be that people who are less experienced with LEDs need to adjust their grow methods a bit with such systems to maximize results as the character of the light footprint is somewhat different using LED panels. The incandescent bulbs (HPS, HID, etc.,) typically used for indoor growing emit the majority of their light in a band around thier axis, and utilize a reflector system to direct most of this energy into a cone of light, additionally they produce a lot of light throughout the visible and infrared spectrum generating a lot of heat and creating a lot of useless light that contributes nothing to plant growth but makes such environments warm and brighter to human eyes. The LED systems tend to be much more narrowly focussed, in terms of both the light frequencies they emit and in the footprint of the light they emit (we are essentially talking about a bank of diode lasers with lenses that disperse the beams rather than focussing them)¹.

I suspect that some problems might come from growers who try to plug and play substitute LED panels in the stead of their HPS systems without taking into account the footprint differences. Likewise, the perception of the LED grow systems producing less fill light is due to a combination of this footprint difference and the fact that they generate all of their light energy in two very specific wavelengths of light that maximize plant growth but don't provide a lot of the unneccesary fill light (wasted energy) that our eyes find convenient in terms of seeing.


¹- ironically, current generation LED grow lights deal with this issue in a different manner. Since we have banks of such emitters, newer panels utilize design mounting variance and lens deflection in the manufacturing process to produce a much wider footprint than the typical HPS reflector system. This is a relatively newer feature on the grow light panels to accomodate the greatly lowered heat emissions of the system and allow growers to move the lights much closer to the growing plants,...ISTR that optimal height above plants for such LED systems is 8"-12" but don't hold me to this number, I'd have to research that to provide support for this recollection.

 

[mhaze]

Good comments, Traker. I'd also note that the "heat footprint" of the light source is critical here in South Texas. Maybe in Canada it's an assist, but here, jacking up CO2 means pretty much an airtight greenhouse. Even the extra 5-10F permissible with higher Co2 doesn't mean that the heat output of the HID/HPS can be tolerated.

Not with 104F outside ambient temps in the summer.

Also, it's radiant heat, which is the worse kind. I'd want radiant LIGHT, and the soil heated from below.

Lots of inter related factors.

 

[mhaze]

....to grow my Hatch chili plants, basil and such? Naw. Not yet.

A major argument against any LED purchase for plant growth augmentation is the expected price drops in the products.

That means your investment needs to be recaptured in just a year or two -- because retail prices will be dropping. So hurry up....and wait....

 

[Dan O.]

A major argument against any LED purchase for plant growth augmentation is the expected price drops in the products.

That means your investment needs to be recaptured in just a year or two -- because retail prices will be dropping. So hurry up....and wait....

That's true for many emerging technologies. If the sales don't increase because everybody is waiting for the cheaper price, the price won't come down and we all miss out on the better cheaper product and the accompanying energy savings. It's a classic catch-22.