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LED Grow Results: Grams per Watt

GMT

GMT

The Tri Guy
Veteran
420giveaway
Ok so with the new price cap of 28p per kWh, running two 300w LEDs, 12hr each, and a 50w fan for 10hours a day, and another 40w of veg lights, I reckon it's costing me (rounded) £70 a month on the grow. I reckon I harvest 4 X per year, with big light veg time, down time ect. I'm averaging £800 per year electricity costs alone. Then equipment replacement, then nutrients at around £50-80 per year, depending on how generous to the plants I feel. Before accounting for time, that's almost £1k per year for weed costs.

What's the value at the moment? £175 per Oz?
So I need 160 grams per year to break even on my setup. Ignoring the cost of the space. Or just under 6 ounces.
That's a more useful measurement for me. Now I just need to count ounces per year. Let ya know next year.
 
Three Berries

Three Berries

Active member
My AC Infinity fans uses about 10% per speed of ten speeds of total watts. It's an EC motor. So at the single speed it's only like 5 watts or 50 at top speed.

When figuring out electrical loads you should always overestimate by 20% of full load.

If you do not have arc fault circuit breakers or even grounded outlets you should at least have use a ground fault interrupter outlet Even without grounding this gives you electrical leakage protection. Does nothing for over loads.

And a surge protector if you have any electronic devices.
 
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negative37dBA

negative37dBA

Well-known member
Veteran
I will toss in my not so impressive numbers But they are honest. It was my second run with a LED and I had just changed to Jacks...no excuses just facts. Good full room, 4x5, 4 plants in RDWC.
630 watt PLC led light. 1.26 GPW. That is if you count 630 watts the whole 9 weeks they flowered. Not sure how to calculate the fact it was not at 100% most of the time. I can do better.
1.26 gpw - Copy.jpg

Peace all, negative.
 
zachrockbadenof

zachrockbadenof

Well-known member
Veteran
negative37dBA said:
I will toss in my not so impressive numbers But they are honest. It was my second run with a LED and I had just changed to Jacks...no excuses just facts. Good full room, 4x5, 4 plants in RDWC.
630 watt PLC led light. 1.26 GPW. That is if you count 630 watts the whole 9 weeks they flowered. Not sure how to calculate the fact it was not at 100% most of the time. I can do better.
View attachment 18733314
Peace all, negative.
Click to expand...
who cares about gpw (unless u are a commercial grower) .... its the quality that counts....
 
GMT

GMT

The Tri Guy
Veteran
420giveaway
Trick to high gpw is low watts per square foot. The return on light input has diminishing returns. You need higher for quality, lower for gpw yields. The issue is, higher gpw numbers tend to mean lower grams per square foot. I think chasing gpw is self defeating. Grams per square foot is more important. The space needed will always outweigh the cost of electric. Maximise space efficiency, not electric efficiency.
 
Ca++

Ca++

Well-known member
GMT said:
Trick to high gpw is low watts per square foot. The return on light input has diminishing returns. You need higher for quality, lower for gpw yields. The issue is, higher gpw numbers tend to mean lower grams per square foot. I think chasing gpw is self defeating. Grams per square foot is more important. The space needed will always outweigh the cost of electric. Maximise space efficiency, not electric efficiency.
Click to expand...
Most seeds list yield per meter. I have never seen info offered regarding light requirements (except regarding photoperiod).

If your power use is limited, then it might become very important that you get good returns from it. Also, commercially, you would be a joker if you didn't know production costs.

An illegal grow in your wardrobe has no real power use concerns. Your legal concerns are reflected in the legal system. Things like plant count and space occupied, lead to profit calculations. The power load isn't a legal consideration. So indoors we are usually trying to use as much light as possible, not as little as possible. Using light inefficiently isn't seen as naughty, but enlarging the grow to get the same effect is a risk to your freedom.


Some of these pointers make chasing gpw counterproductive. In that wardrobe scenario, we might half the light but only lower yield 25%. It would be a win for gpw, but a bad crop. We have to presume everybody playing the gpw game is also playing for maximum yield in a given space. That is how the playing field becomes level.



It's interesting to see this threads findings over the 11 years of LED development it covers. There are still glaring problems though. Peoples ideas of what 'dry' means for instance. How many months the grow took. The known percentage of people that simply lie to have the best figures. We can't make a science of this.
 
Switcher56

Switcher56

Comfortably numb!
Ca++ said:
Most seeds list yield per meter. I have never seen info offered regarding light requirements (except regarding photoperiod).

If your power use is limited, then it might become very important that you get good returns from it. Also, commercially, you would be a joker if you didn't know production costs.

An illegal grow in your wardrobe has no real power use concerns. Your legal concerns are reflected in the legal system. Things like plant count and space occupied, lead to profit calculations. The power load isn't a legal consideration. So indoors we are usually trying to use as much light as possible, not as little as possible. Using light inefficiently isn't seen as naughty, but enlarging the grow to get the same effect is a risk to your freedom.


Some of these pointers make chasing gpw counterproductive. In that wardrobe scenario, we might half the light but only lower yield 25%. It would be a win for gpw, but a bad crop. We have to presume everybody playing the gpw game is also playing for maximum yield in a given space. That is how the playing field becomes level.



It's interesting to see this threads findings over the 11 years of LED development it covers. There are still glaring problems though. Peoples ideas of what 'dry' means for instance. How many months the grow took. The known percentage of people that simply lie to have the best figures. We can't make a science of this.
Click to expand...
:good:
 
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