Agriculture Reference
In-Depth Information
FIGURE 3.3
LED light fixtures with a mixture of four red and four blue tube
lamps. (Courtesy of Sunlight Supply, Inc., Vancouver, Washington.)
cost from $50 to $120 depending upon their wattage. The reflectors cost
from $40 to $80.
Today, new LED lights are being promoted for their low consumption
of power. There are a number of types where the blue and red can be
mixed at varying percentages in a reflector unit to provide the best light
for specific crops. LED lights for growing plants are available as LED
tubes or arrays in various types of fixtures. LED tubes, as manufactured
by Sunlight Supply, Inc., are 4 feet in length and fit into 4-foot fixtures.
Two fixtures are available, one to contain four LED lamps and the other for
eight lamps. They are flexible to mix and match different colored lamps to
give the desired spectrum for growing (Figure 3.3). Fixtures range in price
from $115 to $190 for the four-tube and eight-tube ones, respectively.
LED arrays, as stated by Apache Tech, Inc., were designed as an alter-
native to HID lights in greenhouses. They claim that these LEDs last for
50,000 hours (about 6 years). They also state that these light arrays use
approximately 80% less power than HID lamps and produce the same
intensity. The light arrays are available in white, red, and blue, or as a
combination of white and blue, white and red, and red and blue. Color
combinations are in the ratios of 1:3, 3:1, and 1:1. There are 120 one-watt
bulbs in an array that produces an equivalent of a 1000-watt HID lamp.
They work on 120 or 240 volts. The arrays cost from $1000 to $1200 each.
Phillips is also doing research on applying LED lighting to horticul-
ture. Phillips does have some lights that are presently available for use
with crops and developed an LED “interlighting” system that provides
light between the plants without generating any heat. These lights are
being used by some commercial growers to achieve greater control over
plants' growth.
