Solar Electric Power: Using Holographic Concentrators to Improve Efficiency

The use of solar electric power has grown significantly in recent years, particularly in Europe, China and the U.S. The worldwide output of solar installations remains relatively small (~7 GW), primarily because of the high cost of refined silicon and low solar module (PV) efficiency. However, recent breakthroughs have occurred in optical devices to improve the efficiency of the solar-collecting cells and to concentrate greater amounts of solar energy on the cells.

In the December 2008 issue of Laser Focus World, the article, "Holographic planar concentrator increases solar-panel efficiency" by Rosenberg, Kostuk & Zecchino, describes the holographic planar concentrator (HPC) as an approach that achieves both these goals. A holographic film is used in a planar concentrator that:

• Collects more indirect and diffuse sunlight throughout the day, and concentrates it on the solar cell. This “passive tracking” allows the collector to produce electrical power for more hours during the day, and during overcast conditions.


• Filters the sunlight, allowing only useful wavelengths to strike the photovoltaic (PV). The unwanted wavelengths are blocked, thus preventing a temperature rise which decreases the efficiency of the PV process.


• Solar modules with HPC cells are currently being developed to incorporate “bifacial PV cells”, which means that the solar light can strike both sides of the cells, improving the efficiency and using less pure silicon. The reduction of silicon, and other improvements have lowered the cost of a solar module below a dollar per watt.

So it’s quite possible that solar electric collectors are becoming sufficiently efficient and competitive that the rapid expansion of solar energy may be realized in the next few years. Some U.S. plants that will manufacture solar PV systems are scheduled to open in 2009.

It appears that optical devices, such as the HPC, will provide the critical technology that is needed for solar PV’s—another field where photonics is an “enabling technology.

OP-TEC staff and Partner Colleges will continue to track the solar PV development to identify new careers for photonics technicians.

What are your thoughts on the possible emergence of solar electric energy? Do you know of educational courses or programs that are addressing technician needs in this area?

Reference:
Kostuk, Raymond K., Rosenberg, Glenn & Zecchino, Mike (December 2008). Holographic planar concentrator increases solar-panel efficiency [Electronic version]. Laser Focus World, (29)12, pp. 41-44.