User:MCoykendall/Concentrated Photovoltaics

Concentrated Photovoltaics (CPV) is one of the newest forms of solar energy technology on the market today. CPV systems focus a large amount of sunlight onto a small area of solar photovoltaic materials to generate electricity. A solar tracker is employed to keep the focal point on a solar cell as the Sun moves across the sky to maximize the power of the sunlight throughout the day.

History
The concentrating of the Sun to aid in the performance of tasks is nothing new, with the earliest instances coming from ancient China. Early concentrating photovoltaic projects and advances occurred in the solar thermal space, with the first patents for the Stirling system being filed in 1816.

The real advances in the concentrated photovoltaics space came much later, with much of the research and development taking place from the 1970s until today. Sandia Laboratories in Livermore, Calif., was the site for most of the early work, with the first modern photovoltaic concentrating system produced there late in the decade. This system used a point-focus Fresnel lens that focused on water-cooled silicon cells with two-axis tracking.

Advantages
Unlike traditional, more conventional flat panel systems, CPV systems are often much less expensive to produce, because the concentration allows for the production of a much smaller area of solar cells. Currently, prices are nearing $1/watt. At this cost, it is conceivable that CPV will soon reach grid parity.

Solar concentrations of CPV systems can range from 2 to over 300 suns. Systems with the highest concentrations (HCPV) integrate optics to concentrate the sun to these high levels. As the concentration increases, the efficiency of the solar cells is boosted as well.

Challenges
CPV systems operate most efficiently in concentrated sunlight, as long as the solar cell is kept cool through use of heat sinks. Diffuse light, which occurs in cloudy and overcast conditions, cannot be concentrated. To reach their maximum efficiency, CPV systems must be located that receive plentiful direct sunlight.

Because of their size and land-cost issues, many power plants utilizing CPV systems are placed far away from the electrical grid. As a result, they are often located far from transmission lines, adding to both the time and cost for deployment.

CPV companies

 * Concentrix Solar
 * Pyron Solar
 * Cool Earth Solar

Photovoltaic industry associations

 * SEIA: Solar Energy Industries Association US trade association