Anthony, I had the same issue on my 380. However, I left my solar directly connected to the
battery, and am in the process of putting in ammeters (analog) so I can read what is going in. To see what is going out, that sort of shows on the instrument panel.
The issue is that if you wire the neg into the master shunt, because
Lagoon uses a switch on the neg (I am talking about the
battery T handle switches), if you or someone else turns this off, then you are not going to be
charging the
batteries from the
solar panels.
I had thought of taking this switch out and just leaving the pos switch, then
wiring in to the shunt directly poses no issue. But until I do this, I don't want to make the mistake of that switch being off and being away from the
boat and it is not charging!
So I am currently going from output of
MPPT controller direct to battery neg. YMMV