why don't Solar controller mfg/sellers use honest ratings

example most 30amp controllers are listed at 390w of panels

and 40amp controllers at 500w of panels

but we don't charge batteries at 12.0v we charge at 14v or higher

14v*30 amps 420w output, going to need more than that input

40a*14v 560w output to batteries, controller must handle at 600w input

500w with 17.5 actual output 12v nominal panels only equals 28.57 amps into and thru Controller NOT 40 amps

so will these controllers really handle the rated amps ? which means a much larger array than the stated max

or are they just blowing smoke..uykw

30 amp ? 390/17.5v = 22.28 amps max from the array
so what is it really a 25amp controller ?

30amps charge at 14v =420watts out , 17.5 * 30 = 525 input
you need 525w panels to get 30amps out at 14.0v

this of course does not included mpppt panels although the same mfg/sellers are doing the same thing playing loose with the words