One thing that puzzled me for some months after I installed a trimetric was low amps from my solar. What I finally discovered was my generator start cables were wired directly to the battery. I didn't think it mattered because I wasn't interested in the small amount of power occasionally consumed to start the generator. What I didn't know at the time was the negative to the generator was also frame grounded at the generator. This created a bypass path around the shunt. The fix was to lift the generator negative at the battery and all was well. CHECK YOUR GENERATOR DC NEGATIVE!