Non-tracking solar collectors

Abstract

The invention concerns a non-tracking solar collector which includes laterally spaced, radiation-transmitting prisms (26) which are wedge-shaped in cross-section. Each prism (26) has major side surfaces (28, 30) converging at an acute angle (32) to a relatively narrow end (34) of the prism (26), and an opposite, relatively wide end (36). For each prism (26) there is a refractor (22), typically a linear refractor such as a linear Fresnel lens, arranged over the prism (26) to refract solar radiation incident thereon onto the major side surfaces (28, 30) of the prism (26), as the sun moves relative to the earth, at angles allowing such radiation to enter the prism (26) and be internally reflected towards a target (38) at the relatively wide (36) end of the prism (26). The refractors (22) are spaced laterally apart from one another, possibly by intermediate, radiation transmitting panels (24) which are continuous with the refractors (22). In the preferred construction, the refractors (22) and intermediate panels (24) form an integral part of a roof or wall cladding structure.

Description

BACKGROUND TO THE INVENTION[0001]THIS invention relates to non-tracking solar collectors.[0002]There exist numerous devices designed to concentrate solar radiation for the purpose of generating electricity or heat. In the case of electricity generation, the function of the solar collector is to concentrate the radiation onto relatively small photovoltaic (PV) cells, while in the case of heat generation, the function of the collector is generally to concentrate the radiation onto a conduit or container conveying or storing a fluid, such as a liquid or gas, the temperature of which is to be elevated.[0003]In the known devices it is recognised that for efficient collection and concentration of the solar energy it is necessary for the device to track the sun as the position of the sun relative to the earth changes during the year and / or as the position of the sun relative to the earth changes during the day. A single-axis system aligned N-S (north-south) should track the sun E-W (east-w...

AI Technical Summary

Benefits of technology

"The present invention provides a non-tracking solar collector that includes wedge-shaped prisms and refractors that refract solar radiation incident on the prisms onto their major side surfaces. The prisms are arranged in a pattern that allows the radiation to enter the prism and be internally reflected towards a target. The refractors are spaced apart from one another and can be continuous with the prisms or panels that form the cladding structure. The narrow edges of the prisms can be adjacent to or in contact with the linear refractors, and there may be reflector structures between the prisms. The secondary solar concentrator has a higher refractive index than the material of the prism and meets it at a curved interface. The invention can be used for electricity generation or heating applications."

Problems solved by technology

The apparatus required to achieve such movement can however be expensive and complicated.

Where electricity is to be generated with the use of PV cells an added disadvantage of systems which employ a focussing lens is the fact that dirt particles on the lens create shadows which result in uneven distribution of radiation on the PV cells.

Apart from the fact that this reduces the efficiency of the PV cells, it can also cause permanent damage to the cells.

Dirt particles on the reflectors of a reflector-type concentrating system can also be problematical.

A disadvantage of the system is however a relatively low concentration ratio of around 2:1.

The low concentration ratio is indicative of a low level of efficiency.

The concentration ratio is however again relatively low, indicating a low level of efficiency.

An additional disadvantage of each of the known systems described above is the necessity for a tracking system to enable the system to track the sun.

Yet another disadvantage is the fact that each of these systems provides an independent collector which must be mounted externally on a roof or other supporting structure where it will be appropriately exposed to solar radiation.

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