Why modern patrol avionics need electrical power as well as space

Why would a Beaufighter struggle to carry modern patrol equipment if propeller aircraft have room for it?

The original Beaufighter would need more electrical power as well as space, and fitting extra generators would add to the space requirement.

Room for avionics is only part of the problem in adapting a Beaufighter for modern patrol work. The original aircraft would also lack the electrical generating capacity needed by much of the equipment. Additional generators would consume more of its limited space. The comparison concerns systems on the scale of a P-8, leaving open less demanding uses for a smaller aircraft.