LED illumination enumeration
The blizzard of 2016 has come and gone. The days are starting to lengthen noticeably, the chickens are laying eggs again. Thoughts turn to what else but seed starting and the plans for garden 2016! In anticipation, I got the bright idea to try LED light tape (see what I did there?) Not sure where I got the idea but it’s clearly not novel, as a cursory google search will confirm. Strangely, not many people using LED grow lights are interested in growing tomatoes indoors…
Anyway, back to my project. I have a 48″ x 18″ shelving setup I’ve used for several years with fluorescent T12 or T8 shop lights, six bulbs per rack at 40 or 32 Watts per bulb, respectively, on for 16 hours/day for at least 3 months. It has served me well for several years.
I usually have three shelves going at a time given the number of plants I start for myself, local community garden, neighbors and colleagues. Three shop-lights per shelf, thus 18 bulbs in all that use 420 kWh/month. Costs me a little over $25/mo total to run this setup. Not going to break the bank but if the LED strips work adequately for plant growth I’ll be down to a total of 200 watts for the three shelves vs almost 600 watts with the shop lights. Should be less than $9/month to run the three shelves.
There are other costs for the fluorescents too that need to be figured in. The bulbs need to be replaced, usually annually, as they get dimmer with age and cost $3 each. The old bulbs have to be driven to hazardous waste, a 40 mile round trip! Ballasts fail and have to be replaced. So when totaled up if the LEDs support comparable growth of the plants it’s a significant improvement and will pay for itself in a few months. The LEDs also take up virtually no head space on the shelf which will support taller plant growth.
After a bit of reading about the different types of LED tape lights I compiled a list of parts from Amazon. I chose a 15 meter strip of 5630 daylight LEDs. 60 watts total for the entire strand. The strand is cuttable every three lights where indicated. The strand has 300 LEDs total.
Since the shelves are 4 ft long I cut the strand into 4 pieces. Each piece is connected with solderless connectors. Easy to do, just open the clip and slide the tape into the slot on the end so it slides under the contacts on the clip. Snap it closed and connect the other side to the next piece of tape (making sure positive goes to positive)
Four strands affixed to the underside of the shelf with the factory adhesive and small pieces of duct tape for added insurance (reviews would suggest that the adhesive on the strips is pretty poor). If the duct tape doesn’t hold I’ll go for double sided tape.
Plug into a 12v 6A transformer.
Place it back on the racks and have a look. Since the lights are now immobile the plants will be moved up and down as needed to keep the canopy a few inches below the light.
My first impression is that they are not going to be bright enough to adequately drive photosynthesis or keep the plants from stretching and getting “leggy”. The contingency plan is to add another 4 strips effectively doubling the light, but also doubling the initial expense and the power consumption. It will still be less than the fluorescents though.
Here is my parts list and cost. Note that the initial cost is less than the cost of three cheap shop-lights and T8 bulbs.
$32 plus tax, shipped. Now for the real test. I’ll sow a flat of tomatoes this week and see how they do!