Remember,…. Panels are like people
Doesn’t stand straight up,…Some things hang out the front,….some things hang out the back,…. And some items are further than others,….
Depending on what you have,…you may need to add or subtract “arm” to get the correct moments,…..
(don’t ignore the wiring)
And weighing, if done correctly, should confirm your numbers…… or cause you to rethink what you assumed/included. ( be sure plane is level)