Are LEDs Misunderstood?

[knna]

The treehugger in me wants to reduce my carbon foot print but these LEDs are not what they are advertised to be. Looking at the lumens per watt figure for LEDs from sources like Mouser it seems clear to me that a 300 watt LED has no chance of getting close to what a 1000 watt HPS will do. Aside from a slight advantage of being more directional I'm not seeing any advantage.

Mouser is not the best place to buy LEDs. If you want good LEDs, you must go to especialized distributors or know very well what you are looking for.

Currently you can get easily an R5 bin of the Cree XP-G, emitting 139lm (minimun) at 350mA (aprox 1.12W), resulting in at least 125 lm/W. Taking into account their LER is about 300lm per optical watt while HPS LER are near 400, they have an energetic efficiency near 25% more per lm. So actually they are over the level level of unreflectorized HPSs in term of energy output. If you consider losses at reflector (and worst yet, glasses form aircooled hoods), this LEDs have a true output 25-30% higher per watt burned.

Its a nice improvement, but its only profitable on small setups due that way higher price per lm of LEDs.

But this is comparing just white LEDs. LED grow lamps uses mostly red LEDs, that have higher photosynthetic efficacy, and emits more photons for each optical watt due the longer wavelenght.

And with LEDs, you have the option (wasted when brick style lamps are used) of distribute the light much more evenly than with any HID. This can enhance the efficacy of the light for another 25-35% easily.

Then you must consider the longer lasting of LED lamps. True, its far from 100Kh, but still if you get a duration of 30Kh at least you are getting 3x the life of an HPS bulb, and likely, way more.

When you put all this advantages together you find that good LEDs (not bad ones) may be cheaper on the long run (on about 3-4 years), especially if the cooling of HIDs requires expensive and/or powerful ventilation systems. If AA is used, LEDs are clearly profitable, due they pay themselves in little time on electric bill savings.

In general, the smaller the growing space, the more profitable is the LED alternative. Probably on large setups (using 600W or higher of HID), LEDs still are a more expensive alternative, always AA is not used. But they will be profitable on large setups on no many time, 2-3 years as max.

 

[PetFlora]

THANKS KNNA

SO MANY OF THE ANSWERS ARE SCIENTIFIC AND WELL OVER MY HEAD, THOUGH I AM VERY CURIOUS ABOUT THE SUBJECT, I SIMPLY AM NOT GEEKY ENOUGH TO ROLL MY OWN LEDS.

MANUFACTURERS COULD MINIMIZE COMPETITION BY BEING PROACTIVE- IF THEY WOULD SPEAK HONESTLY TO PEOPLE LIKE ME. THEY SHOULD BE UPFRONT THAT WE WILL EXPERIENCE SIGNIFICANT LUMEN LOSS AND FAILURE AROUND 30KH, BUT, OFFER US A REASONSIBLY PRICED REPAIR/EXCHANGE PROGRAM WHEN THIS HAPPENS. I THINK MORE PEOPLE WOULD BUY IF THEY DID

 

[420atheist]

Thanks Knna. That is great information. I knew I was not asking too much to get a few facts. I think I will stick with HPS for a while longer. However I do feel a little more educated than before. I will keep an eye on LEDs as my operation is small enough to make them work.

 

[SupraSPL]

@Petflora. If you can solder you can build your own LEDs, no geekyness required

True, even a properly cooled LED array will suffer lumen depreciation over time. However compared to HID the difference is staggering. A correctly built LED array will be at 97% output after two years of continuous 12/12 use. By then you will have access to more efficient, cheaper emitters so you can either keep using it, replace the emitters or build an additional array with higher efficiency.

When it comes to the cheapo lamps promising miracles, KNNA already said it well, they are crap. If they were being honest with you, they would have to say that they are equally efficient as fluoros when it comes to flowering.

 

[darko_G]

too much conflicting info on the net about led's this man loves that man hates... its driving me crazy. i moved from a room into a cab where heat and noise must be at a minimum. means my extractor fan is a nono. so i bought an 9k btu ac for £175. this was also way too loud. gotta return it. so i think its gonna have to be led. ima buy the 205w led from LEDgirl for about £550 shipped out. and try it out on my first sog. i dont have a clue whats going to happen. i got 1 succesfull outdoor and one succesfull indoor under my belt

 

[renz]

Although I agree with most of your post, this paragraph shows a very typical misunderstanding of LED lighting, that I would like to correct.

LEDs allows you to grow very big plants, as only HID vertical lighting allowed before. With LEDs, you dont depends on the light penetration ability of the light, you can surround one or many plants with LEDs. As LEDs run cool, they can be close toplants without any problem,thus allowing to run big plants without the need of use excessive irradiances on top, that is a very inefficient way of lighting plant, but the only possible way before LEDs to grow big plants.

It's not a misunderstanding; I've made several posts concerning concentration of power in a single emitter and focus angles and distribution and emission direction of dissipated heat, etc...

More of a comment about whats available to the non technical grower who can't just throw this together themselves in a weekend.

You can get even more penetration with higher power emitters, at the cost of thermal performance, and efficiency. So 3W category LEDs are neat and everything, but 10W isn't uncommon and in a couple of years likely multiples of that will be available in a single compact package (like in mass quantity, not just mutant white emitter stuff on dealextreme).

 

[renz]

Oh, and I'm still waiting for someone to post any info about what current regulation circuits are used in commercially available arrays. All this talk of LED efficiency vs each other is kind of ridiculous when you can be losing as much energy in the circuits driving them.

Maybe I suck at forum search iunno...

One would hope that *all* of the grow arrays being sold are based on switch mode current regulators... but people mentioning burnt up transformers makes me wonder.

I will straight laugh if any of these products are using resistors and 60Hz transformers to 'regulate' current.

Please, someone who knows wtf I'm talking about, please prove me wrong. Seriously this is at least as important as the LEDs you are using if you are serious about efficiency. I know maybe it's confusing to people who aren't comfortable with electronics and are struggling just to learn optics stuff, but it's not trivial at all.

 

[knna]

Oh, and I'm still waiting for someone to post any info about what current regulation circuits are used in commercially available arrays. All this talk of LED efficiency vs each other is kind of ridiculous when you can be losing as much energy in the circuits driving them.

Maybe I suck at forum search iunno...

One would hope that *all* of the grow arrays being sold are based on switch mode current regulators... but people mentioning burnt up transformers makes me wonder.

I will straight laugh if any of these products are using resistors and 60Hz transformers to 'regulate' current.

Please, someone who knows wtf I'm talking about, please prove me wrong. Seriously this is at least as important as the LEDs you are using if you are serious about efficiency. I know maybe it's confusing to people who aren't comfortable with electronics and are struggling just to learn optics stuff, but it's not trivial at all.

Yep, the efficiency of drivers is a very important question.

Old chinese LED lamps, and some still on sale of low power using throught hole LEDs uses very inefficient and uneliable ways of limiting current. But almost all LED lamps in the market using high power LEDs uses switching power supplies. Simply because they are cheaper currently.

UFOs and so uses bad ones reliability wise, but efficiency wise they are not bad, due they mostly uses very long strings, about 100V each, and its very easy to get high efficiencies when the gap between input and output voltage is reduced. In the case of UFOs, efficiency is between 80 and 84%. It could be higher if they use lower switching frecuency and larger inductances (more expensive), but its good enough.

A LED growing lamp using a switched driver designed for the lamp can have an efficiency over 90% and close to 97% if the manufacturer not build for the cost, due the long arrays used.

 

[renz]

Thank you, knna.

And yeah, 97% seems like the magic number in a lot of the higher performance constant current driver datasheets. I wonder if it's possibly also the sound of very low frequency drivers that puts designers off. Because you would think sales guys would go nuts if they could sell it as "95-100% efficient". Copper and ferrite is expensive and everything, but it's not like they aren't getting a huge markup on the product.

I built a low voltage 3 rail DC converter that switched at 20KHz... on power up, the frequency ramping would make a 'PEW' noise like a Star Wars blaster, then the three inductors would buzz together like tiny rattlesnakes. I thought it was pretty neat, but someone who didn't know what was going on might be a bit concerned, heh.

 

[renz]

When it comes to the cheapo lamps promising miracles, KNNA already said it well, they are crap. If they were being honest with you, they would have to say that they are equally efficient as fluoros when it comes to flowering.

Haha, at one point there was UFO propaganda that stated that LEDs were more efficient than HID. That they were the most efficient light source in the world!

If you can drop power consumption by 20% without changing very much about how they are used compared to HID, that's pretty significant. It may not be very exciting to sell, but in the real world, operating procedures are changed and equipment is upgraded to save much, much less. 20% would be huge.

I'd still want to see side by side controlled environment testing with the results dropped off at one of those weed lab places, but it looks like savings of at least that much is possible in the near term. Which is way fucking neat.

 

[PetFlora]

Seems to me (a non-techie) that the efficiency often mentioned has to do with LEDs not wasting energy producing spectrums that have very little (seemingly) to do with what mj needs to grow and bloom. Y/N?

 

[SupraSPL]

That is a good question Petflora. What I get from KNNA theory, if we compare big HID versus top binned LEDs (~40% radiometric efficiency) we can accept that they both output the same amount of photons per watt consumed. If we tune the LED spectrum almost perfectly we can expect ~25% increase in yield/watt over the HPS spectrum.

We can get another ~25% thanks to the directional output of LEDs, lack of reflectors/lenses and the more even spread of photons across the canopy.

So in theory if you can yield 1 gram/watt for a given strain with a big HID you should be able to get 1.5 gram/watt with that same strain using a good LED setup. We can improve that slightly in the future by using even more efficient LEDs. 55% radiometric efficiency LEDs should be available this fall.

 

[knna]

Seems to me (a non-techie) that the efficiency often mentioned has to do with LEDs not wasting energy producing spectrums that have very little (seemingly) to do with what mj needs to grow and bloom. Y/N?

Although it's true, but that factor is often exaggerated.

It's due that LED growing lamp sellers uses the graph of chlorophills absorbance to tell that most of the energ emitted by other light sources, as HPSs, are wasted. And it is not true. Plant uses very well all photons into the PAR range (400-700nm). Green light is not wasted as many people says.

Its true that plants uses a little better some wavebands into the PAR range than others, and that LED lamps mostly emits on those wavebands. But the gain in efficacy of light due this factor, although good, is very far of claims of LED lamp sellers. They say that using LED spectrums, light efficacy is multyplied by 8x or 10x, and the fact is that usually gain is about 1.25x.

And its different for veg and for bloom. In veg, its possible to get enhancements of efficacy of 2x very easily, but in bloom, its way more complex. MJ need at little of most wavebands along the PAR range to perform well in bloom.

I have found some spectrums able to get an efficacy of light(yield/photons) close to 2x (compared to HPS's spectrum), but its done using some wavebands that many LED lamps sellers says that are wasted. Right now, nobody knows exactly how to design an spectrum that works optimally.


So the argument is true, but the way you find it explained to make you think that other lamps waste light so LED lamps works so much better, is a marketing argument without relation to reality. This is the basis of marketing, take a valid point and use it where is not actually valid, but may seem to be.

 

[PetFlora]

The treehugger in me wants to reduce my carbon foot print but these LEDs are not what they are advertised to be. Looking at the lumens per watt figure for LEDs from sources like Mouser it seems clear to me that a 300 watt LED has no chance of getting close to what a 1000 watt HPS will do. Aside from a slight advantage of being more directional I'm not seeing any advantage.

I wouldn't jump to that conclusion. Current commercially produced LEDs overlook the importance of other spectrums, especially green, as well as the benefit of underside lighting. I know one person who is working on a new LED that addresses these issues as we speak.

 

[gates3rd]

Hey,

i fallen in love with the blinky blinky led, i plan a DIY light with the new Cree led`s, just for veg cause there is just white and warmwhite so ill maybe use some 6500k cree high power led`s for veg. i wanna get near to 4000-8000 lumen like my veglamp now have.

i know lumen isnt everything but for a veg lamp i think its okay.

i found Lighthouse LED lights and they look really nice, with orange and violett cree led`s and they are not so overpriced if they work like they promise .. but its a try to use more of the aviable nm range.

 

[SupraSPL]

Cutter had some reasonably priced Cree reds and they were a decent bin. The could enhance a vegging lamp or allow you to build a flowering lamp. On the other hand the reds KNNA has are much better.

 

[habeeb]

^ yeah, I wonder how the lighthouse hydro does in veg, with all those whites in that light!!

I'm sure it works good, how good is to be tested by someone... HAHA.. not me this round as I have to many led's now.. and to little space now

 

[squarepush3r]

so do people deny that this is the chlorophyll absorbtions spectra?

 

[headband 707]

I have noticed that you ask questions about LED light but you don't get the answers you need LOL .. example bringing plant to flower with LED?? I also hear they have new LEDS from China that are not out yet that are very powerful lumins to date. peace out Headband707

 

[tokinafaty420]

I wouldn't grow with LEDs, but I do invest in LED tech companies. Will definitely be the future when it comes to househould lightbulbs, no doubt in my mind.