Great point. 326 suns is like adding “supercharged” fuel for cars. It can be used in space though, where sunlight is much more intense.
First is the high efficiency. Yes, this is higher than previously reported, but only marginally so, as compared to a similar structure by Spectrolab (40.7% I recall) a few months ago. It's like a 0.5 in improvement in the pole vault record. A new record, yes, but no earth-shattering breakthrough. Nonetheless, it is a good result.
The second issue is one of concentration. Think magnifying glasses and ants on a sidewalk. The accompanying article alludes to this. Typically, one places a cheap plastic Fresnel lens over the cell (ok, it's marginally more complicated than that) and focuses the sunlight onto a small area. The “one-sun’ efficiencies for these cells are typically in the 30+% range but the structure is, in fact, optimized for concentration. Concentrating the sunlight onto a small cell is - overall - much better than using more solar cell material to get similar power out under ‘one-sun conditions.
And these cells are more expensive than their silicon counterparts so high efficiency under concentration (more or less replace more expensive solar cell material with a cheap plastic lens) makes them more economically viable. Earlier generations of this type of cell are indeed used in most satellites, not because of the concentration (sunlight is not that much greater in space) but becuase of the higher efficiencies at low weight. One still needs large areas, etc, however, to produce decent power...
Of course, they are closer to the sun. :-)