As Shyam Mehta suggested in his recent piece of solar analysis:

After manufacturing cost, efficiency is perhaps the most closely examined and easy available competitive metric. Module conversion efficiency is inversely proportional to area-related balance-of-system costs, such as land, substructure, racks, labor, and cables.

SunPower (NASDAQ: SPWRA, SPWRB) just announced their newest solar panels with total area efficiencies of more than 20 percent. The 96-cell solar panels use SunPower's 22.4 percent efficient cells and boast a positive power tolerance rating.

The prototype for the SunPower panel was developed using funds provided four years ago by the U.S. DOE under its Solar America Initiative.

SunPower has been the heavyweight champion of the world when it comes to commercialized cell and module efficiencies for the last half-decade -- and by a significant measure. The company's back-contact cell design, in commercial production since 2005, moves the metal contacts to the back of the wafer, maximizes the working cell area, and eliminates redundant wires. SunPower has been able to achieve consistent improvements in efficiency with each successive generation of commercialized cells, and this has translated to gains in the module arena as well. The firm's Gen 3 cells have efficiencies in excess of 23 percent.

SunPower is likely to be the efficiency leader when it comes to high-volume PV cells and modules for the foreseeable future. The problem, as this article by Michael Kanellos points out, is that 24 percent is awfully close to the realistic ceiling, meaning there may not be much further to go from there. 

At Intersolar this week, Suniva announced an efficiency conversion of more than 16 percent with 260 watts from a 60-cell panel. As we've reported, Suniva uses ion implantation amongst other techniques to drive efficiency gains.

Suntech (NYSE: STP) announced a new generation high-efficiency module at Intersolar with up to 15.2 percent conversion efficiency. These modules use 18 percent efficiency cells, but not the high-efficiency Pluto technology.

Other high efficiency solar players include Sanyo’s HIT technology at 17.7 percent cell efficiency and a number of established Chinese c-Si players vying for the third spot, such as Yingli and JA Solar.