Remove the solar from the equation. Turn off the inverter. Begin at the shore power. Using a volt meter measure all contacts. I'm gonna assume you have 30 amp serves. Hot to neutral = 120 volts. Hot to ground = 120 volts. Neutral to ground = 0 volts. Now plug in and go do the same test on the female end of your shore power cord. Plug that in and go remove the cover from your main panel box. Turn off all the breakers. Do the same test again on the wire coming in from the shore power cord. Turn on the main breaker. Do the test again on the buss bar and ground and neutral bars.
If you haven't found it by know you need to turn on the breakers one at a time while you test the buss bar and the ground and neutral bars. Remember Neutral to ground should always 0 volts.
You must start at a Good shore power and work your way back. If you don't you make yourself crazy. Do not jump around out of order.
