sentences:  On June 23, 2010, The company announced that it has produced a full-scale solar cell with a sunlight to electricity conversion efficiency of 24.2 percent, a world record confirmed by the U.S. Department of Energy's National Renewable Energy Lab (NREL).However, EnergySage only rates SunPower photovoltaic cells as 22.2% efficiency at maxium, at the top of an 'efficiency range' of 16% to 22.2% - though at the top of its list of the best five solar cell production companies in America.After the cells are constructed, conventional assembly system uses a robot to place the cells into a grid of 6 columns of 10 cells - other arrangements are used, but rare outside commercial settings.