How far can we push the solar efficiency envelope? (image from jhritz on Flickr)

There are two factors that every solar cell manufacturer considers: cost and efficiency.  Of course, we want the first factor to go down, and the other one to increase.

When companies improve the efficiency of solar panels, they can promise more bang for the buck.  Instead of 10 solar panels on your roof, perhaps 8 panels could generate the equivalent solar electricity!  In other words, when more efficient solar cells produce more power, you save money and get a quicker return on your solar investment.

One question that lingers, however, is how far can we push the solar efficiency envelope?

Is there a ceiling of maximum efficiency?

When weighing the two factors mentioned above – cost and efficiency – some companies are willing to sacrifice a bit of efficiency to keep prices down.  In order to maximize conversion rates of solar cells, expensive materials and/or technology is often required.

Suntech Power Holdings ran into issues last year with its highly efficient solar cell, dubbed “Pluto.”  Although it broke efficiency records, the company lowered production forecasts in part due to factory-based automation issues.

Solar efficiency hangs in the balance

Experts in the field believe that, no matter how much we push solar efficiency, current technology can only improve the existing watts/dollar ratio by a few percentage points.

With silicon-based solar panels, the upper limit is approximately 33%, and more realistically 28-30% efficiency.  Cadmium-telluride and CIGS cells also have a predicted limit of 28-30%.  Calculations are made using each semiconductor’s band gap, which refers to the amount of energy (photon) required to push electrons around, which determines a material’s ability to absorb and convert light to electricity.

Even with current limitations, researchers will continue trying to improve the efficiency of solar panels.  Consider the following record holders:

• USNW produced a multi-material solar cell with 43% efficiency
• USNW also produced a monocrystalline silicon cell with 25% efficiency
• The Fraunhofer Institute in Germany created a multicrystalline silicon cell with 20.4% efficiency
• The National Renewable Energy Laboratory (NREL) came up with a Cadmium-telluride cell, converting at 16.7% efficiency
• NREL also created a copper, indium, gallium and selenium (CIGS) cell with 19.4% efficiency

What new records will be shattered in 2010?  Stay tuned for more solar panel manufacturing news in the weeks and months ahead…