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mattie

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Reply with quote  #1 
Hello all
Here's another question regarding a greenhouse.So far the focus has been on keeping thermal energy in the structure.
There is of course the other key element that plants need to grow and that is light.If you want to create an environment that allows for year round growing surely daylight hours in the winter months will play a key role in growth rates.A lot of commercial growers utilize artificial lighting systems to ensure more consistent crop yields.

What might be the best route to take with this? A pv setup with battery bank and LEDs to extend the daylight hours.I know that LED systems can be expensive, are there any other thoughts or ideas on this.Ive seen online (i have to locate the link) a clip on building your own LED lighting maybe this is the more cost effective approach.
Regards Mattie

solardan1959

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Not being a grower, I've always heard of "grow" lights.  (not all light is created equal)  Does it matter? I would generally use florescent lighting which I have heard can be run straight from DC, not sure if that is true or not, but that might make it better for DC applications.  Also this would be cheaper than LED and not use that much more power.

Dan
mattie

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Thanks Dan,
You're right with the fluorescent lights T5s could be a possible solution.
I'm still learning regarding plant growth and lighting fixtures.A lux meter or some sort of light reading device could be set up to trigger on and off when greenhouse light levels drop In order to make use of natural light when its available to save energy.

I found this clip which may be of use to some others out there which has some good info on fluorescent lighting.



The larger the greenhouse gets the more fixtures needed.Which in turn increases the electrical requirements, pushing the size of battery banks and number of panels needed higher ,the end result here is more money needed initially for set up costs.
Regards Mattie


solardan1959

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Reply with quote  #4 
Mattie,
  More on my DC theme and lowering wattage requirements.


probably more playing than most people want to do.

Dan
gbwillson

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Reply with quote  #5 
Mattie-

Good video link. I've used fluorescent bulbs for years to grow my seedlings. I didn't know the spectrum decay was quite that fast. I used to change out my bulbs every two seasons. Just a note: The green ended bulbs do not contain mercury.

I used to have a table in front of the South window of my house covered with seedlings. Over the top of the seedlings were grow lights. These lights were on almost all the time and created quite the glow coming from my house. My neighbors used to joke with me about growing pot in my house. So one day I made a large paper cutout of a pot leaf and placed it in my window just to give my neighbors something to laugh about. Well, the next day I had 3 cop cars show up at my door! Since my house is right across the street from a park with a kiddie-pool they took the report very seriously. Anyone who knows me knows how ridiculous the accusation was. All they found was about 800 flower seedlings. The cops laughed about it as they said someone apparently called in about a "huge" pot plant in my house. I guess the joke was on me, so I left the cutout up the rest of the growing season just to cheese off the person who reported it.

Greg in MN[biggrin][biggrin][biggrin]
KevinH

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800 seedlings...  Wow!  I thought I had gone overboard this year with my 250 (vegetables and a few flowers).  I give a lot away to family, friends, and a plant sale that benefits a wildlife refuge.  I'm going to set up a temporary greenhouse soon I made last year using conduit and covered with poly.

A couple years ago I saw an interesting LED lighting system for greenhouses at an energy expo.  The LEDs were on a narrow aluminum bar maybe 1/4" thick that they could make to any length.  They could customize the wavelengths for the plants being grown and the intensity and spectrum could be adjusted during the growing season.  At that time they were doing one for a big orchid greenhouse in California.  Systems like that are probably a way off for home greenhouses, but it will get there some day as LED prices drop.  There are LED lights on flexible strips powered by 12VDC.  You would need to find ones bright enough to help in a greenhouse.

Kevin H
MN
mattie

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Hello all,
Thats an interesting clip Dan and a great way to run florescent tubes on dc,probably more time consuming than i would like to set up for a full greenhouse.I wonder when the wattage is lowered are there elements of the lighting spectrum important to plant growth affected somehow?Im not at all sure of this its just a thought i had, tbh theres a severe need for me to spend more time researching lighting systems in greenhouses its a fairly large topic from what ive seen,feeling a bit bewildered currently.This may be useful to others http://theaquaponicsource.com/how-to-aquaponics/indoor-aquaponics-grow-lights/

Hello Gbwilson sounds like you have a lovely neighbour lol,you were right to leave it up kind of a constant reminder of their lack of humor.Thanks for the heads up on the bulbs. Glad you liked the clip i posted, theres a series of them on that channel on the different lighting types available.

Kevin H,LEDs seem like a good choice for sure just wish the initial price wasnt so high and the coverage area was more substantial.this seems to be a common occurance high cost and not much area covered(Please correct me here, it will be good to hear Im wrong)When you start adding solar pv panels and the rest the costs start to jump fairly quickly.

My intention is to look at using a lux meter or similar device to make use of natural light when its available and shut of the artificial when its not needed.The Missouri U greenhouse uses white bathroom panelling to enhance solar gains to the water barrels.This should hopefully aid light distrubution in the greenhouse, i may have to wear protective eye wear in there lol.

Regards Mattie
solardan1959

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Reply with quote  #8 
Mattie,
   I used white paneling on the sides and front wall that the light does not shine on for the same reason, to keep things bright.  My back wall is dark to absorb light.  When the sun is out it's plenty bright in there and sunglasses are in order.  I'm giving up a little solar gain by having the sides white and as it is getting above 20F it's starting to get too warm in there anyway.  Today the wife had the ceiling fan on, the outside door open, the garage door open with a fan blowing the hot air into the garage and it was still too hot at 85F.  But she got some of the seeds started so we are on our way......  Going to have to get more serious about summertime ventilation as the screen doors on each end are not going to cut it.

Why are you so concerned about light?  is that mainly for early spring, late fall, and winter,  or do use want then at night also?

Dan
mattie

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Reply with quote  #9 
Hello Dan,
Its year round growing and daylight hours that's my concern, so yes ,spring ,autumn ,winter or any other day where light conditions are not optimal for plant growth.The backup artificial light can kick in to make sure that crop gets the maximum light exposure each day in order to maintain a consistent yield.
LED Systems look ideal from an efficiency standpoint but cost/area is a big factor here and from what I've seen so far you get a surprisingly small area covered for a high cost light.
I hope im not drifting too far off topic here regarding whats normally posted on the forum.
This may be a case of posting on an aquaponics or commercial greenhouse forum to see what kind of responses i get .
Regards Mattie





kcl1s

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Reply with quote  #10 
Mattie,
LED grow lights are available for the hobbyist... if you can afford them.

http://www.farmtek.com/farm/supplies/prod1;ft_hydroponic_supplies-ft_hydroponic_grow_lights;pg112239.html

Keith 
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