https://en.wikipedia.org/wiki/Shockley%E2%80%93Queisser_limit

Tl:dr The max theoretical efficiency for a silicon solar cell is estimated to be 29.4% with real world high end modules topping out at 26.8%

26% in a lab is not the same as 26% in the field after 5 years, but it is nonetheless a good result.

Solar scales out well, so low conversion effiency isn't really what determines whether an installation is feasible or not.

If you're evaluating cheap 20% efficient panels vs expensive 25% efficiency panels, you need only scale up the area of cheap panels by 25% to match output. Plus, panels that start at a lower efficiency experience less derating over time, so the difference in performance diminishes as an installation ages.

This isn’t exactly like wasting coal generated electricity through inefficiency. It’s not like we are wasting limited sun.

Many commercially installed panels are around 21% efficiency. That's up from about 18% even ten years ago. There are panels that dramatically higher in conversion, but they tend not to be cost-effective or capable of lasting. Wikipedia has an article on it, and a chart that show the highest research cell NREL has tested is 47.6%. To quote "They reach their highest potential when the incoming sunlight is concentrated by lenses onto miniature solar cell devices of just a few square millimeters in size." So not production ready nor large deployment.

26% is utterly insane and depraved.

Haw haw haw oh man you sure gotcha'd them. They're all so STUPID and you n me we're the SMART ones!

Not today, but it would have been pretty impressive in the 80's. This is a newer type of cell, so let's see how it does as the technology matures.

Try buying a commercial silicon PV module with 26%.