The small solar cell in the picture below is now a part of solar energy history. That is the new concentrator triple-junction solar cell Sharp created and it has an efficiency of up to 44.4%.
Sharp recently announced this record with a press release (click here to read the complete press release). The previous record was 44%, as you can see in the graph below. This graph is from National Renewable Energy Laboratory (NREL) and the most recent version can be seen by clicking on this link. They will, of course, have to update the graph with this latest development.
The basic cell setup is explained in the following picture. These concentrator triple-junction solar cells are not for house-holds yet. Crystalline Silicon is still the most cost effective solution for public use even though the average commercial solar cell shows about 15-18% efficiency. These expensive triple-junction solar cells are especially used in space-crafts.