This New Solar Cell Can Harness Almost All of the Energy in the Solar Spectrum

July 16, 2017

A new solar cell prototype, developed by scientists from the George Washington University, is capable of converting just under half of the available energy from sunlight into electrical power. The novel technology does this by using a particular family of materials assembled in a stacked structure, which allows the solar cell to harness nearly all of the energy in the solar spectrum.

[Image Source: George Washington University]

How exactly does this solar cell work?

This new solar cell prototype is using concentrator photovoltaic (CPV) panels. The panels are equipped with lenses that concentrate sunlight on cells with a microscale dimension of just less than one-millimeter square. By designing the panel at such a tiny scale, new and diverse solar cell materials can be developed.

What sets this solar cell prototype from previous solar panel designs is the employment of a particular material and the way the whole system is assembled. The solar cell is made up of a group of materials based on gallium antimonide substrates (GaSb) that are more commonly found in infra-red lasers and photodetectors equipment. The GaSb solar cells are crafted in a stacked structure and are integrated with high-efficiency solar cells made from traditional substrates capable of capturing shorter wavelength solar photons. Furthermore, by assembling the solar cells using the stacked method, the scientists were also able to exploit a technique called transfer-printing. The technique permits a three-dimensional, microscale cell structure that possesses a high degree of precision, which allows the device to capture almost all of the energy in the solar spectrum.

Solar cell prototype by George Washington University

[Image Source: George Washington University]

How does it compare to conventional solar panels?

Each layer of the stacked solar cell prototype can absorb solar energy with a specific set of wavelengths. This process of absorbing sunlight in a filtering manner result into harnessing, and converting 44.5% of the available solar energy into electricity. Whereas conventional solar cells are only capable of converting a quarter of the available energy into electric power. Matthew Lumb, a research scientist at the University and lead author of the study, explains the advantage of creating a solar cell using the transfer-printing technique.

“Around 99 percent of the power contained in direct sunlight reaching the surface of Earth falls between wavelengths of 250 nm and 2500 nm, but conventional materials for high-efficiency multi-junction solar cells cannot capture this entire spectral range. Our new device is able to unlock the energy stored in the long-wavelength photons, which are lost in conventional solar cells, and therefore provides a pathway to realizing the ultimate multi-junction solar cell”.

Creating a solar cell with such a complex structure comes with a great price. The GaSb-based cell is considerably much more expensive than conventional solar cells, of course. But the researchers think it’s important to exhibit the optimal efficiency capacity of such a renewable energy material. They are looking to develop the current form of the solar cell using low-cost materials with very high solar concentration levels and technology that can recycle the costly growth of substrates. Through this way, the researchers may be able to market a similar product to the masses.

Via George Washington University

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