On: Germany sets new solar-power record

[mchannon]

Energy-storage technology isn't inefficient. Energy-storage technology is expensive.

[skore → mchannon]

"Efficiency in general describes the extent to which time or effort is well used for the intended task or purpose."

Comparatively high cost is the main factor why it is still be considered less efficient although that is slowly changing.

[mchannon → skore]

If you go on to the next paragraph in the wikipedia article you copy-pasted without citation, you'll see "The term "efficient" is very much confused and misused with the term "effective". In general, efficiency is a measurable concept, quantitatively determined by the ratio of output to input. "Effectiveness", is a relatively vague, non-quantitative concept, mainly concerned with achieving objectives."