I was thinking about KT sine wave 60V 45A, but I gave it up becouse of its gigantic size (255x85x45). The box has space calculated on the GT1500 and nothing bigger will get in.
The dimensions of the GT1500 controller are 180x87x43 [mm] (without cables and eyelets for screwing).
Later I got the Sabvoton MINI controller (SVMC072045 72V 45A). Unfortunately, it also turned out to be too big (too high). Out of curiosity, however, I dissassembled this Sabvoton MINI and it turned out that half the volume inside is air. That’s why I decided to take a risk and change the housing in it.