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Publication Date: 2011-Jul-15
Document File: 4 page(s) / 144K

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The Prior Art Database


Solar hybrid lighting systems using tracking are complex and high cost, but are ineffective in diffuse light conditions.The innovative device disclosed in this publication uses a transparent solid material, such as PMMA (poly methyl methacrylate) or glass,in the form of a cylinder that is embedded or coated with a fluorescent dye, as a solar light concentrator. The dye absorbs sunlight and re-emits the light isotropically according to its photoluminescence spectrum, which is then transmitted to a fixed luminaire inside a building through fiber optics.Other advantages of the innovative device include longevity, lack of moving parts, scalability,and low cost.

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This publication is related to the field of solar lighting, which is the use of sunlight to illuminate an indoor environment. This can be achieved principally by the transport of light by means of optical fibers from a solar collector to a luminaire inside a building. There is no requirement for an electrical or artificial light emitting apparatus. In hybrid lighting systems, the collected light may be supplemented by artificial lighting, in order to increase the light intensity or modify the emitted spectrum.

Currently, all of the commercially available solar hybrid lighting systems incorporate a tracking solar concentrator with mirrors or lenses. Exposed moving parts and optics add significantly to the complexity of the solar hybrid lighting system and operation and maintenance costs. These systems perform poorly in diffuse sunlight or cloudy conditions. The described disclosure publication solves these problems by employing a collector that has no moving parts, which can collect diffuse sunlight and can be manufactured and installed at low cost.

There are several problems associated with the tracking of concentrator systems for solar hybrid lighting. The sunlight tracking in the solar hybrid lighting systems must be highly accurate (almost less than 1 degree precision). This will increase the complexity of the system causing reliability issues. The disadvantages of these tracking solar hybrid lighting systems are given below:

1. Moving parts associated with the solar hybrid lighting system reduce the system reliability and increase maintenance costs.

2. The solar hybrid lighting system and optics are generally very expensive.
3. Direct sunlight is essential for the performance of the optics of the system. This means performance could be poor in diffuse or cloudy conditions.

4. The area of sunlight collection of an individual concentrating optical component is limited. Therefore in order to enlarge the system, more components and associated tracking systems are necessary. There is no significant reduction in the cost of the system as the size of the system increases.

5. It is widely claimed that solar collectors provide aesthetic and health benefits as they allow the natural solar spectrum to be experienced indoors. Recent studies show that the absorption bands in the fiber optic cables used to transport light significantly affect the spectrum of the emitted light. This means that claims of providing natural, unchanged sunlight are inaccurate.


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Extensive research has been conducted on luminescent concentrators for solar lighting by a company called DayRay (formerly Fluorosolar). Their design uses a planar concentrator which makes coupling to a fiber optic system more complex.


Aconcentrator for solar lightingis disclosed with reference to the drawings:

Figure 1 shows solar hybrid lighting system with cylindrically shaped...