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Trying to reduce grow light electric bill

Posted by keepitlow 6/7 (My Page) on
Thu, Oct 15, 09 at 9:29

My electric bills keep going up and the electric company said it is going up about 42% over the next 4 years. This is my first season growing under lights. I am running 16 - 4 foot 40W florescent tubes in my setup. I am growing lettuce, arugula, beet greens, red Russian kale, mesclun, and scallions for use in salads this winter.

What do you think the minimum amount of light hours these veggies will tolerate? Can they get by on 6 or 7 hours or light?


Follow-Up Postings:

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RE: Trying to reduce grow light electric bill

That's over 640 watts because the ballasts use some power. You can try 250 or 400 watt HID lighting or LED (see other threads on these topics).

I note that Menards, in the Chicago area, is advertising 2 watt warm white Sylvania LED Accent bulbs for $7.99.

I also note that Sylvania either offers or is going to offer 40 watt LED bulbs to replace 250 watt HID bulbs for street lighting, http://www.sylvania.com/BusinessProducts/Innovations/LEDLampsandRetrofits/posttop.htm


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RE: Trying to reduce grow light electric bill

They are making kits to change from T12 to T5. The initial cost is high but will save you some dough in the long run. I believe the T5 bulbs use 27w each so that's a 13w difference and a 208w savings all together. You may be able to use less fixtures also because T5 puts out more lumen than T12.


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RE: Trying to reduce grow light electric bill

I would think the best way to lower your bill would be to stop growing food indoors. From an ecological standpoint you are wasting precious electrical energy. A lot of the stuff you are growing could survive pretty cold outside temperatures.


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RE: Trying to reduce grow light electric bill

Not everyone lives in sunny California. From an ecological stand point, it probably makes more sense to grow food under lights at home, in the winter, than buy fresh produce trucked all the way from california to sit in a refrigerated case, especially when a significant percentage goes to waste because no one bought it. I use 14 20 watt CLF's at 280 watts total ( less than my TV burns), with a light output of 16,800 lumens. Even if I was growing cool weather crops like the person above, I don't think they'd do to well when it's 16 degrees F like today.


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RE: Trying to reduce grow light electric bill

It may not be quick solution to the problem, but I had an idea how to heat and light a green house in a green way. Build a wood gasifier to fuel a gasoline or diesel generator. I'll build an extra quiet muffler (so my neighbors don't complain) that will double as a heat exchanger to keep my green house warm, and also route the mostly CO2 and water vapor exhaust into the green house. The system will be able to burn everything from waste paper to leaves and grass clippings. The food plants sink the CO2 and get a boost from it. The water vapor from the exhaust can even be collected with a cooling coil and stored in a tank to water the plants. The ash can be put into compost. Technology can be the answer, if you think about it.


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RE: Trying to reduce grow light electric bill

I don't have figures for anything but lettuce, but if the other veggies are similar, you will need about 12 mols/day of light. That's equal to 2,000 foot candles (or 21,520 lux) for eleven hours. Or 4,000 foot candles (~43,000 lux) for 5.5 hours. If you can get the lights within an inch or less from the plant canopy, you can come close to achieving the 43,000 lux.

If you don't need the plants to grow quickly and can keep the temps lower, you can get by with less light but it will take longer for the plants to grow.

Mike


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RE: Trying to reduce grow light electric bill

Do you have a chart to figure out how much light plants need?


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RE: Trying to reduce grow light electric bill

Yes, though it is not specific:
light chart
The data is on Pages 25 & 26 or maybe 26 and 27! The figure for lettuce came from a book, "Lighting Up Profits" that is geared toward maximum efficacy of lighting in green houses.

HTH,

Mike


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RE: Trying to reduce grow light electric bill

keepitlow; I don't think 6/7 hours of florescent would cut it. I tried ten hours and had almost no growth at all. I am on 18 hours per day and growth is great. Buttercrunch Lettuce,Swiss Chard,Blomesdale Spinach,Pock Choy and Tatsoi. I have 262 watts tube and cfl's in just over 8 square foot. As far as cost the garden is in my kitchen witch has an east facing double window as the only natural light source. So part of the cost of lighting is what I would use to light the kitchen with out the garden. That cost was 60 watts of cfl for 10 hours a day. Now the rest of the power Goes into heat witch while more costly than the fuel for the furnace.Is none the less not a waste of power at all, and is circulated by fan. Maybe you should rethink your garden location and place it in a more advantages setting?

Curt :-) 50% of my power bill goes to renewable energy most of it wind power.


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