FAQ
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SOLAR LIGHTING FAQs

 

 


What does LED stand for and how is it used?

LED is the acronym for a light-emitting diode. An individual LED emitter is a semiconductor diode that emits light when voltage is applied. LED technology has been around for several decades for specialty applications and has evolved recently to the point that it is being used for general lighting applications.

 

What is an LED array?
LEDs are typically used in clusters of multiple LEDs known as LED arrays.

 

Why has it taken so long for LEDs to catch on for use in general illumination?
Initially the lumens per watt were less than what general-use fixtures required. In addition, initial approaches were applied to retrofit existing fixtures to house the new LED technology. These traditional lighting standards and housings were not applicable and certainly not optimized for LEDs, unlike the fixtures used today.

 

Why do LEDs not function efficiently in traditional fixtures?
LEDs have different challenges; the optical design used in traditional fixtures is not optimized for the efficiency, inherent qualities and directed lighting capabilities of LEDs. Thermal management requirements also are different than those for other types of lighting (incandescent, fluorescent, etc).

 

What are the benefits derived from using solid-state LED lighting?
LEDs offer several key benefits over other lighting options, including higher energy efficiency (lumens/watt), better durability and a significant reduction in maintenance costs due to their longer life. These benefits translate into a lower overall product-life cost.

 

What's the difference between efficacy and efficiency in lighting?
Efficacy in lighting is primarily concerned with the amount of light (in lumens) produced by a certain amount of electricity (in watts). Lighting efficiency, on the other hand, is the ratio of total lumens exiting the fixture as opposed to the total lumens initially generated by the light source.

 

What is the proper way to compare LED products?
Considerations should include lumen output, the overall luminaire efficiency and optical control LED thermal management. An LED light's product lifetime is typically defined as complete once the fixture has reached 30% lumen depreciation. A high quality LED will likely deliver more average lumens/watt than traditional High Intensity Discharge (HID) light fixtures. The Department of Energy (DOE) determined that solid-state luminaires should be evaluated based on overall efficacy (i.e., for the entire luminaire, including LEDs, drivers, heat sinks, optical lenses and housing).

 

What benefits do LEDs offer over traditional HID fixtures?
A well-designed LED luminaire with super-bright white LEDs offers high lumens per watt, better optical efficiency, minimal lumen depreciation, a significantly longer life span, no hazardous materials like mercury, and less waste production, and they are made from fully recyclable materials.

 

Do I need to replace LED diodes?
No. LEDs do not burn like a standard lamp but gradually generate lower output level (lumens) over long periods of time. If one LED fails, the other LED diodes continue to generate light.

 

What is the life span of an LED?
The life span of an LED is significantly longer than that of other lamp sources like incandescent, fluorescent or HID and can reach 50,000 hours or longer. An LED never really burns out; the product life span is measured by lumen depreciation (IES calculates the life of an LED based on 30% lumen depreciation). You may see claims of a 100,000-hour rating, but this is not equivalent to lamp life rating (at 30% lumen depreciation). At 100,000 hours an LED is likely still to be operational but at a lower output in lumens.

 

What does the estimated life span based on 50,000 hours of operation translate to over time?

12 hours per day 11.4 years
10 hours per day 13.6 years
8 hours per day 17.1 years