MPPT controller for offgrid system in parallel with Grid tie Inverter

Hi, can anyone comment on my planned project.
So i have a total 1,200 watts panel which supplies my current 1Kw Grid tie system. I want to add another MPPT in parallel with my Grid Tie, both getting power from the Solar Panel. Will this work?
My thoughts:

1. both grid tie and mppt will get >60v and should function at the same time but power will be divided to the 2 system
2. I was thinking if the battery will be charging at 20amps it will be at 80-90% charge in 4 hours and BMS should cut the supply making the Grid tie the sole leecher from the panel
3. The offgrid will only function at night to supply some garden lights and wont be using 80amps, maybe just 40 amps max in 10 hours, so maybe it will be just take 2 hours to reached 90% charge capacity.

Would appreciate any inputs

If you live in a climate that sees temperatures below about 50°F, your panel voltage will exceed your MPPT 150 Voc max. Cold temperatures cause panel voltage to increase.

snoobler said:

If you live in a climate that sees temperatures below about 50°F, your panel voltage will exceed your MPPT 150 Voc max. Cold temperatures cause panel voltage to increase.

Click to expand...

Oh defenitely will not happen. Out average temp here is 86 F, coldest ever recorded was 75 F

Biggest issue is if one of the two (GT, MPPT) ties PV leads to some DC level. Then there is a serious fight.
Small cheap grid-tie inverter is likely transformerless, does not have galvanic isolation between PV panels and AC grid.
Other is confusion between MPPT algorithms, each seeing disturbances it didn't create.
If you want to run one or the other but not both at the same time, that could be arranged.
Probably better to have one system powered by the other, or get a hybrid with PV, batteries, backfeed to grid, and protected loads (your outdoor lighting.)

That's a way better solution.

MPP powered by house grid via AC in, so it becomes just another load powered by grid/grid-tie. The issue will be if grid goes down, you're not getting any solar.

However, it wouldn't take you but 10 minutes to move your panels from the grid tie to the off-grid.

Appreciate your feedback, am using a Solis Grid tie, i think this is a good one, been using it for 9 months now. It has a limiter and sensitive enough to shutdown for any voltage fluctuation in our area.
And yeah my main concern is i dont know which of the 2, the GT or Mppt will max out the power from PV panel.
I considered the mppt powering the battery then connect to the GT but wanted it separated since the outdoor consumption is so low (and not connected to the house grid).
My other plan is putting a transfer switch, manually switching it, though i could try the original setup and pray nothing will break

Hedges said:

Biggest issue is if one of the two (GT, MPPT) ties PV leads to some DC level. Then there is a serious fight.
Small cheap grid-tie inverter is likely transformerless, does not have galvanic isolation between PV panels and AC grid.
Other is confusion between MPPT algorithms, each seeing disturbances it didn't create.
If you want to run one or the other but not both at the same time, that could be arranged.
Probably better to have one system powered by the other, or get a hybrid with PV, batteries, backfeed to grid, and protected loads (your outdoor lighting.

Click to expand...