Equivalent wattages between LED and HPS?

[BigB]

Is there a guide somewhere that compares the usable lumens per watt of LED to MH or HPS? I am used to growing under halide and sodium lights, but would like to experiment with triband and quadband LED. Is there a table somewhere that shows how a given wattage in LED compares to HPS or MH? What wattage HPS or MH would be required to get a comparable amount of light usable by the plant from a triband or quand band LED (ie x LED = y HPS)?

[Brotherly Monkey]

most LED manufacturers use "equivalency ratings" as a selling point for their product, but as far as I know, these never really pan out. And are more a gimmick to get the consumer over the initial effects of sticker shock

My best advice: check some marijuana forums. You should be able to find numerous in home, side by side, comparisons on the two products

PS just make sure those comparisons aren't done by the manufacturer. For some reason, they always turn out better than the ones being done by an actual consumer...

[littlefrog]

Probably need at least 600W of LED to match a 1000W metal halide.

I'm looking seriously into buying a bunch of LED's, but it is pretty confusing right now.

[Ray]

Lumens per watt is one measure of lighting, as is watts alone, but you have to consider the specific spectrum emitted, as well.

For example, an HPS bulb may put out something in the neighborhood of 140 lumens per watt, but at a color temperature of about 2100°K, most of the spectrum is in the red end (essentially none in the blue end of the chlorophyll absorption spectrum), and the energy flux is quite low.

By contrast, a 6400°K high-output T5 fluorescent bulb may put out roughly 90 lumens per watt, but its spectrum very closely matches the blue:red ratio of chlorophyll absorption, and the energy flux in the red end is 1000x greater than that of the HPS bulb.

I recently acquired some 6500°K phosphor-type LEDs, and (in my spare time) will be assembling a "single-pot plant light" as an experiment. I'll keep you posted.

[Brotherly Monkey]

Originally Posted by Ray

I recently acquired some 6500°K phosphor-type LEDs, and (in my spare time) will be assembling a "single-pot plant light" as an experiment. I'll keep you posted.

what wattage are they?

[littlefrog]

Right now the 'standard' for grow LEDs is a mix of blue and red. Better lights have a couple flavors of them both. LEDs emit light in a very tight spectrum, so if you are looking for a wavelength, you need to put it in.

The concept is 'PAR' (photosynthetically active radiation). Supposedly there is special meter to read PAR, I don't own one. Much of the white light spectrum is wasted, your plants are green because they don't absorb green light... So, by using LEDs you can focus on the light that plants need. What that boils down to is that it is very difficult to compare HPS/MH, fluorescent, and LED lights. Total lumens aren't the right way, what matters is PAR lumens.

So, to grow plants efficiently, you want LED lights that only output light in the wavelengths orchids use. You are going to be stuck with lights that look like a bad B grade science fiction movie. They won't be white. If you want white, don't get LEDs, you are missing the point of the exercise if you do that, I think. In that case, you will be using a lot more power to get the same growing effect, might as well use fluorescents at that point.

Needless to say, I've been doing some research. What I need is to break down and buy a few different brands (or make my own, in my copious free time - maybe Ray will make me some!). It is expensive to test a lot of lights, though. I can probably get them wholesale, perhaps we could do some sort of group buy and experiment.

[BigB]

I have a little 90 watt triband LED light that I quite like. There's not a lot of waste heat and my orchids under it seem to be doing very well. I like it enough that I want to expand my LED use.

The reason I asked about comparisons was that the LED vendors claim a single 300 watt LED bank can replace two 1,000 watt HPS lights. I really like my little 90 watt light and it is amazing for the energy use, but I don't trust the miraculous claims of salesmen. And I don't need the equivalent of two 1,000 watt HPS lights. I would like something around the equivalent of a single 1,000 watt HPS. Maybe even a little less. So I was hoping someone who had some real world experience with LED lighting could give me some advice on sizing an LED upgrade.

The PAR lumens information is on the right track, but just using red and blue LEDs is last year's model. Using the PAR approach current LED banks are using up to 7 different colours of LEDs. The basic triband I have uses a ratio of 7:1:1 red: blue: orange. The red light is for flowering, the blue is for green growth, and the orange gives the flowers better colour.

I am really liking the results I am getting with it. I'm not interested in a theoretical discussion of "could this strange new technology possibly work?" because it obviously is working right now in the real world. I just need sizing information. These systems really put out the light and I don't want to harm my orchids with too much light.

[Brotherly Monkey]

As I said above, if you look in particular places, that are more geared towards artificial light, you'll find people doing side by side comparisons. So you can see for yourself, say, how a 1k HD compares to a 600 led. and even how 1k compares to 1k


PS from my understanding, the higher wattage LEDS can run pretty warm, so it might be best to plan on some issues with heating. At least above what you currently experience with your 90 watter

[littlefrog]

I'd run screaming the other way if somebody claims a 300W LED can replace two 1000W HPS. That is some sort of fantasy land.

I also don't know about this trend towards increasing the number of colors... 4 is about right. 7, 9, 20... Pretty soon you are competing on how many colors you offer, might as well use white light which we all agree isn't what the plants actually need... Just my thought.

I'd love for somebody with more experience to chime in too. I am seriously considering doing ~600sq feet of growing space (in about 900 sq feet of actual space) under LED, but I'm a little reluctant to spend that much money without more feedback.

Originally Posted by BigB

The reason I asked about comparisons was that the LED vendors claim a single 300 watt LED bank can replace two 1,000 watt HPS lights. I really like my little 90 watt light and it is amazing for the energy use, but I don't trust the miraculous claims of salesmen. And I don't need the equivalent of two 1,000 watt HPS lights. I would like something around the equivalent of a single 1,000 watt HPS. Maybe even a little less. So I was hoping someone who had some real world experience with LED lighting could give me some advice on sizing an LED upgrade.

The PAR lumens information is on the right track, but just using red and blue LEDs is last year's model. Using the PAR approach current LED banks are using up to 7 different colours of LEDs. The basic triband I have uses a ratio of 7:1:1 red: blue: orange. The red light is for flowering, the blue is for green growth, and the orange gives the flowers better colour.

[BigB]

Judging by the lack of experienced responses, Brotherly Monkey probably has the right idea here. Perhaps I should be asking the pot growers for LED comparison info. They tend to be pretty much cutting edge when it comes to technology.

I totally agree with you littlefrog that claiming 300 watts LED = 2x 1,000 watts HPS is probably sales hype having little to do with what I can expect to achieve with the lights. My take on the 7 band and 9 band LED systems is that it may be complex past the point of optimal return.

The colour light these units generates looks approximately fuschia to the eye. The plants look pretty normal under LED light as of course they are absorbing the reds and blues while reflecting the green light. The rest of the room however, kind of glows pink.

Apart from the questionable claims of lighting salesmen, I am really liking my 90 watt LED light (the brand name is UFO). I've been using it for a little over 6 months now. I am growing paphs, phals, Dens, Blulbos, Paphinea, Promenea, Dendrochilum, and vanilla as well as Siningia, Streptocarpus, ferms and moss all together under this light. I figure that's not bad for one 90 watt light.