White LED Lighting

Summary

Until recently, though, the price of an LED lighting system was too high for most residential use. With sales rising and prices steadily decreasing, it's been said that whoever makes the best white LED will open a goldmine.

Details

White LED lighting has been used for years by the RV and boating crowd, running off direct current (DC) battery systems. It then got popular in off-the-grid houses, powered by photovoltaic cells. It used to be that white LED was possible only by "rainbow" groups of three LEDs -- red, green, and blue -- and controlling the current to each to yield an overall white light. Now a blue indium gallium chip with a phosphor coating is used to create the wave shift necessary to emit white light from a single diode. This process is much less expensive for the amount of light generated.

Each diode is about 1/4" and consumes about ten milliamps (a tenth of a watt). Lamps come in various arrangements of diodes on a circuit board. Standard arrays are three, six, 12, or 18 diodes, or custom sizes -- factories can incorporate these into custom-built downlights, sconces and surface-mounted fixtures. With an inexpensive transformer, they run on standard 120 volt alternating current (AC), albeit with a slight (about 15% to 20%) power loss. They are also available as screw-in lamps to replace incandescent. A 1.2 watt white LED light cluster is as bright as a 20-watt incandescent lamp (bright enough to read by).

The lighting quality is comparable to that of cool white compact fluorescent lamps, with color rendering indices near 85. LED lights don't flicker. The light is very directional in small arrays. LED strip lights can be installed under counters, in hallways, and in staircases. Concentrated arrays can be used for room lighting. Waterproof, outdoor fixtures are available, and they operate in temperatures from -20°C to 80°C. Manufacturers consider applications such as gardens, walkways, and decorative fixtures outside garage doors to be the most cost-efficient.

Installation

White LED lamps are available with standard screw-in bases to fit incandescent fixtures. They are much smaller than compact fluorescents and even incandescents, because instead of a bulb, there is an array of tiny diodes lining the rim of the base. They also come as strips that can be used under cabinets.

Benefits/Costs

Imagine never having to change lamps, which consume too little electricity to notice. LED lights work well for rooms with TV or radio because they do not generate radio frequency interference as some compact fluorescent lamps do. They produce little heat, and can operate in hot or cold environments. An 18" strip light, which is the equivalent of a 25-watt incandescent lamp, costs $128. Transformers for AC systems typically cost $6 to $20 depending upon amperage.

Limitations

The biggest limitation to LED for common residential use is the cost of manufacturing due to still-limited production runs. Manufacturers claim production will increase considerably by 2001, further lowering prices.

Code/Regulatory

12V amber LED strip lights meet code for emergency lighting.

Availability

There is a limited number of manufacturers, but this is changing. Some fixtures are subject to backorder until market/production stabilizes.

Contact(s)

Do you have a specific question about this technology and/or its 'real life' applications? Try the contacts listed below:

Holly Solar Products
P.O. Box 864
1340 Industrial Ave.
Petaluma CA 94952
800-622-8716
http://www.hollysolar.com

Brad Wagner
Sloane Precision Optoelectonics
4835B Colt St.
Ventura CA 93003
805-676-3200

LEDtronics
4009 Pacific Coast Highway
Torrance CA 90505
310-534-1505
http://www.ledtronics.com

Advanced Illumination
802-767-3830