here is a different take on your post.
Ok I must be missing something. I need to know how many amps are being put out by my solar panels.
you are interpreting and assuming that the panels will deliver their full rated output and you have divided the panel wattage by 12 Volts to arrive at that 50 Amp value, the value you have calculated is the maximum amperage value used to select an MPPT controller when used in a 12 Volt system.
you don't need to know the panel amperage, I think you meant to say "I need to know how many amps ( or watts ) the MPPT controller is providing"
They are 200 watt panels...3 of them. 12v and wired in series. So my calculator says they should be putting out 50 amps. Then I checked the actual voltage rating on the panels...says 20.4v.
20.4 Volts tells me the panels are not fully loaded, either they are not in full sunlight or more likely, your system is charged and not presenting much of a load. if you were to switch on all your lights and perhaps an inverter with a coffee pot or microwave and load the battery bank, the controller will sense this and increase it's output.
So I redid the calculation...now says 29.4 amps. Sounds more reasonable. However when I check the main line going from the panels to the solar controller, my amp meter only show about 6 amps going through the main wires. What am I missing.
you are using the wrong values for your calculation. the 6 amps you measured at 20.4 Volts equates to
a value of 122 Watts. as I stated in my other post, you do not need to measure these values, the controller does it all for you, just read what it has to say..
additionally, solar panels rarely give anything close to full output. a typical value might be 80% in good conditions.