My controllers have been pretty RF quiet actually, a few ferrite bead on all the wires in and out and all I have left is a couple of birdies here and there. My computer puts out way more noise. The inverters are the rf generators, I searched quite a bit to find a low cost RF quiet inverter and settled on Samlex PST series. So get yourself a handful of RF noise ferrites from Radio Shack and go at it. Morningstar MPPT 45 controllers, they are quietish