100w DS LED

SpaceGhostLos · Aug 30, 2012

I want to start growing but I have no clue how many plants I can grow under a 100w Diamond Series LED light. Does anyone know?

Total Coverage: 2.5ft x 3ft

LED Specs: 3w High Output LEDs (single chip)

NEW - Diamond Series LEDs - Extreme 3w LED Technology - Advanced LED Grow Lights

wwpk · Aug 30, 2012

Have you already bought it?

It would be similar to this great grow:
http://forum.grasscity.com/indoor-grow-journals/1060934-90w-led-ebb-flo-diy-1st-grow-journal.html

If you haven't already bought it, you might want to also check out

Amazon.com: 180W Lighthouse Hydro BlackStar Grow Light 6 Band Band 3W Chips Flowering 180 Watts: Patio, Lawn & Garden

So these are both even at single LED output; using 3W's. But the BlackStar is $65 cheaper. Diamond Series has the upper hand on spectrum capability. It has 11 wavelengths vs the BlackStar's 6. Then again these are pretty much the main 6 needed in flowering. It's also 180W vs 100W and as I understand it reaches maximum optimisation LED output at 150K so the 180K's gunna give you full led's ability while the 100W is still 44.44% away from optimal output. I may be wrong but I don't think so..

TechBuddy said:

For context we were talking about HPS vs LED specifically the "500W" Blackstar LED.

Here's the original thread: http://forum.grasscity.com/organic-...watt-led-grow-experiment-13.html#post15612839

And the quotes:

My response:

His response:

As a disclaimer I am a nerd, I am a teacher, and I ramble. So bear with me. I'm also new, but I have read the 3 highest rated books cover-to-cover (both bibles and the horticulture handbook) and am assimilating as much information as I can from as many sources as I can before I start my (legal!) grow. In other words I may be wrong, and if I am please feel free to correct me.

In regards to your first question about PAR scale and what is useful: the "PAR" scale was designed in order to give some vague sort of standardization to measuring light that is useful for plants. PAR is far more useful than lumens/watt, but it's still not exact. Because different plants have concentrations of Chlorophyll A and B and a wide range of carotenoids that utilize different frequencies of light it was difficult to come up with any sort of exact measurement. In 1972 a scientist by the name of McCree proposed that anything between 400nm-700nm was useful, and based on quantum flux readings it's sufficient to treat all frequencies equally for simplicity.

What this means is that, for example, an ideal light emitting 100W at exactly 560nm (pure green) is considered "PAR" light. However less than 15% of that energy can be used by marijuana plants. So really you're not applying 100W of "useful" light, you're only applying (for argument's sake) 15W. But according to the PAR scale it's 100W.

Now take a look at the emission spectrum of HPS - the vast majority of it's light is in the 575-620nm range, with the peak at 570nm - exactly what the plants cannot use. I haven't done the integration yet but I'd estimate that 40% of the light emitted by an HPS cannot be used by the plant. So right off the bat you're wasting 40%, and that ultimately turns into heat which (usually) has to be removed at a high energy cost, further compounding your energy requirements. Your air conditioner spends 0.3W to pump 1W of heat out of the room. That's 1.3W completely wasted for every 1W of unusable light.

LED lights have very specific emission spectrum, so these grow lights avoid the areas that the plants cannot use - this is why the pictures look so oddly colored.

So consider that most LEDs and HPS bulbs both have "lumens/watt" efficacy of about 150. The PAR lumens will be much less than that for HPS, but pretty much identical for LED because you select the LEDs that are within the PAR range.

Furthermore just like how PAR is more meaningful than lumens/watt, the useful energy/watt is even more specific, and that's where LED will really shine (pardon the pun). This means massive increase in efficacy in terms of usable light per watt despite the "lumens/watt" being roughly the same.

To put this into some non-technical numbers anecdotal evidence suggests that 300W of LED is about the same as 800W of HPS (yes, there are debates still on this, but let's assume that this is correct for the moment). So that's 500W of additional "wasted" energy, plus 150W cost to remove that energy, or 650W of additional energy cost.

At $0.13/kWh at an average of 16h/day over the entire 3-month grow cycle is $123 in extra electricity.

So if your LED setup costs $250 more than an HPS setup it will pay for itself after only 6 months. This isn't even addressing the issue of being able to place the lights closer to the plants, but that's a complicated topic for another thread.

To address your second question about the efficiency of higher wattage LED bulbs:

Fewer bulbs does not mean more efficiency. Bigger is not always better.

Looking at the specifications of lower wattage bulbs they tend to be in the 150 lumens/watt range. Higher power bulbs are usually in the 120 lumens/watt range - meaning you're spending more overall energy per unit of light.

This is the same as the 600W HPS vs 1000W HPS debate. 600W HPS is roughly 150 lumens/watt - 90,000 per bulb (give or take). 1000W HPS is only about 140 lumens/watt - 140,000 per bulb. If you scaled the 600W to 1000W you'd have 150,000 lumens instead for 1000W power draw. In other words you spend 7% more energy to get the same light output with the larger bulb. Three 600W bulbs will put out 270,000 lumens, whereas two 1000W bulbs put out 280,000 lumens. Only 10,000 lumens more, but 200W extra power required. Sometimes smaller bulbs are more efficient; Same goes for LED. It's more convenient and cheaper to use the bulbs with the higher output (which is why manufacturers use them), but the energy cost is higher. The people who build the LEDs aren't concerned with power draw, so the less efficient draw doesn't really matter that much.

Third point about inverse square law. Again this is a complicated topic, as it is not as simple as it is typically made out to be, but for our purposes we can assume that it is. Yes it does still apply here. Double the distance, half the energy per unit area.

However HPS bulbs emit light in 360 degrees, and this is really what is more important than (and the source of) the inverse square rule. You need reflectors and white/mylar walls to try to get as much of that light to your plants as possible. At a distance of 24" above the canopy (and assuming a 2ft diameter canopy) only 53 degrees of that light is directly hitting your canopy (again, this is a simplification). So the other 307 degrees (or 85%!) of emitted light has to reflect in order to get to the plant. Assuming a very generous 25% overall loss before that light hits your plant (due to multiple reflection surfaces, bouncing back into the bulb, not hitting the plant at all, etc) and 22% of your usable HPS light is being lost, again ultimately to heat (which requires energy to remove).

So, in a very large nutshell, this is why LED can be significantly better than any other source. LED emits light in a very tight beam - as tight as 15 degrees. These LED grow lights mix bulbs of varying focus from 120 to 15 degrees in order to get as much light directly to the plant without reflecting.

All of these factors combine to why 300W of LED can be considered equal to an 800W HPS light, and the energy costs will allow it to pay for itself within 6 months.

Reduced energy consumption also has additional benefits for the guerrilla grower as that means less overall household consumption. Even for the legitimate growers it means 2.5X the number of plants for the same household draw. Proper growing is limited by 5 factors, one of which is light. A house with 100A 240V service can realistically only provide about 80A 120V to grow lights, which if using HPS is only about 8000W or about 20 plants at 0.5lb/plant and 0.5g/W of yield. Using LED you can grow 50 plants (assuming the other 4 factors are attended to!) with the same yield per plant.
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rhapsodyrcks · Aug 30, 2012

With that light probably 2 at most. 2x2 is a pretty small area.

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