Opinions on basic truck/van charging system (All in one DC/DC/MPPT?) that will use both alternator and solar for house Lifepo4 battery

[Impatient]

The mppt doesn’t have much to act on if voltage output is close to battery voltage. Open circuit voltage in low light may actually match the label but it has not much current to offer. I meant you can still get some charge as my quoted numbers indicated in very poor light but mppt shines when it has excess voltage above battery static nominal voltage. Mppt really isn’t playing the game well until you give it two or three times battery voltage.

Because the sun wasn’t really up yet. I’m 70-90V+ by 9am in clear full sun.

Open circuit voltage would probably still be 88+ volts per string, just no amps. With the ‘weight’ of the battery load it pulls the voltage down until there’s enough sun to make big volts at any reasonable amps.
There is a law in equation form that ALWAYS solves out: Watts = Volts times Amps.
Example in early sun:
90V at .1A=9W 9W @ 13V=0.69A
Later:
90V at 3.6A=324W 324W @ 13V=24.92A
Later still:
94.5V at 6.56A=620.5W 620.5W @ 14.6V=42.5A

I have eight 100W panels 4S2P:
4 panels in Series (400W) twice; and 2 of those series strings Paralleled
I am running a 50A mppt charge controller

Hmmm. I guess I will just have to see what happens when I get new panel and MPPT hooked up.
Today:
160w (21.75 Voc) panel…~8.5a Imp
Morningstar PWM controller (Prostar 15a)

Proposed (to replace above):
250w (~52 Voc) panel….I just received but too cold outside to play with. ~6a Imp
Victron 100/20 MPPT or equivalent (I haven’t ordered yet).

Today my PWM obviously pulls voltage down to battery voltage, but I thought proposed MPPT didn’t work that way …instead stayed “asleep” until voltage exceeded battery +5 (Victron spec). Your data implies (or at least I am interpreting it such that) MPPT controller will pass a little bit of charge current even with “low” voltage (at or just above battery voltage). What brand controller do you have? It’s possible some other brand besides Victron might operate differently. I also currently have a CTEK MPPT / DC-DC controller, and it “wakes up” at much lower voltage… but it can’t handle a 52v panel…it can handle only 23v input.