Solar modules with enhanced efficiencies via use of spectral concentrators

Abstract

Described herein are solar modules including spectral concentrators. In one embodiment, a solar module includes a set of photovoltaic cells and a spectral concentrator optically coupled to the set of photovoltaic cells. The spectral concentrator is configured to: (1) collect incident solar radiation; (2) convert the incident solar radiation into substantially monochromatic, emitted radiation; and (3) convey the substantially monochromatic, emitted radiation to the set of photovoltaic cells.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit of U.S. Provisional Application Ser. No. 60 / 945,869, filed on Jun. 22, 2007, and U.S. Provisional Application Ser. No. 60 / 977,067, filed on Oct. 2, 2007, the disclosures of which are incorporated herein by reference in their entireties.FIELD OF THE INVENTION[0002]The invention relates generally to solar modules. More particularly, the invention relates to solar modules including spectral concentrators.BACKGROUND[0003]A solar module operates to convert energy from solar radiation into electricity, which is delivered to an external load to perform useful work. A solar module typically includes a set of photovoltaic (“PV”) cells, which can be connected in parallel, in series, or a combination thereof. The most common type of PV cell is a p-n junction device based on crystalline silicon. Other types of PV cells can be based on amorphous silicon, polycrystalline silicon, germanium, organic materials, and Gro...

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Benefits of technology

[0009]Other aspects and embodiments of the invention are also contemplated. The foregoing summary and the following detailed description are not meant to restrict the invention to any particular embodiment but are merely meant to describe some embodiments of the invention.

Problems solved by technology

The inability to convert the total incident solar radiation to useful electrical energy represents a loss or inefficiency of the solar module.

Current solar modules typically suffer a number of technical limitations on the ability to efficiently convert incident solar radiation to useful electrical energy.

Such excess energy is typically not converted into electrical energy but is rather typically lost as heat through hot charge carrier relaxation or thermalization.

This heat can raise the temperature of the PV cell and, as result, can reduce the efficiency of the PV cell in terms of its ability to produce electron-hole pairs.

In conjunction with these thermalization losses, photons with energy less than the bandgap energy of silicon are typically not absorbed and, thus, typically do not contribute to the conversion into electrical energy.

The variation of the absorption coefficient of silicon across an incident solar spectrum can impose a compromise with respect to the depth and other characteristics of the depletion region that reduces the efficiency of the PV cell.

For example, while a particular depth of the depletion region can be desirable for solar radiation at one wavelength, the same depth can be undesirable for solar radiation at a shorter wavelength.

In particular, since the shorter wavelength solar radiation can penetrate below the surface to a lesser degree, electron-hole pairs that are produced can be too far from the depletion region to contribute to an electric current.

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