Improving the efficiency of solar cells

Flat-plate photovoltaics, or PV – which produces electricity by having sunlight directly strike panels made of expensive silicon wafers – has dominated the market. Grid-connected PV is the fastest-growing energy technology in the world.

However, silicon feedstock shortages and rising wafer prices have highlighted the need for technologies that reduce the use of silicon or other semiconductor materials, which usually dominate the costs of the total installed PV system.

Concentrator photovoltaics (CPV) technology offers an effective, practical way to keep solar cell conversion efficiencies high while keeping semiconductor material costs down.

PARC's approach

CPV technologies use relatively inexpensive optics such as mirrors or lenses to “concentrate” or focus light from a relatively broad collection area onto a much smaller area of active semiconductor PV material. CPV systems must be pointed directly at the sun because they work by focusing sunlight onto a targeted area, and therefore require trackers which follow the sun’s trajectory throughout the day. Since CPV systems require less semiconductor material to capture a given amount of sunlight, it's still cost-effective to use more expensive and higher efficiency cells to increase the electricity generated from a given collection area.

Boosting the efficiency of solar cells through thinner electricity-conducting grid lines is another area of focus. PARC has proved that a prototype printer can print uniform lines and is testing the efficiency gains in wafers. On cells with average conversion efficiencies of 15 percent, a 6 percent gain would boost efficiencies to 15.9 percent.

Pictured: SolFocus CPV panel. (copyright 2009 SolFocus, Inc.)

enabling technologies for industry applications

collaboration with SolFocus, Inc.

PARC developed the technology behind SolFocus’ second-generation concentrators, shrinking the concentrators from about one foot in diameter to about 1 inch, and pressing groups of them into a glass tile so they are easier and less expensive to manufacture.

With strong early contributions in non-imaging optical design from researchers at the University of California at Merced, SolFocus' CPV solutions build on PARC expertise in optical system design, optoelectronics, and advanced materials and processes for electronic packaging.

case study and more info

Read the case study ("Accelerating time to market and increasing cost-efficiency") to learn how SolFocus identified a new market and developed new media technology, .

Download the white paper, "Technology advances in delivering cost-competitive solar energy" [pdf].

Learn how PARC works with early-stage ventures.

video: Scott Elrod on PARC's work with SolFocus, Inc.