Can I add second array and 2nd GT inverter to existing GT system?

[bruiserman]

I've got an older set up with 32 -165w Mitsubishi panels on a Sunny Boy 5000. Panels rated 5.28k output, but peak appears to be 3.5k max anymore on any given day, The Max AC output for the SB 5000 is 20.8 amps. I have a 200/200 main panel, so as I understand it, 40 amp is max back feed for main panel to the grid. I picked up a used system for a song of 11- Mitsubishi 185w panels with a Fronius IG 2000 GT inverter, having Max output 8.35 amp. The panels specs are very comparable to each other. The second array would be approx. 90* to the primary array, catching most sun during morning hours. My first thought is to keep the second system totally separate and backfeed at the panel with separate breakers (currently is a 40 amp breaker on SB 5000 output). If I add 20.8 amp + 8.35 amp x 125% = 36.43 amp, which appears that the main panel could handle the actual load. But even if I use a 15 amp breaker for the 2nd system, is it doable? Or if I dropped the first to a 30 amp breaker, it will still be @ 45 amp total breakers, which is over the 40 amp max for the main panel, or am I looking at this the wrong way? Maybe combine the 2 outputs before the main just use the existing 40 amp breaker? Are there other potential issues using two different GT inverters? Just looking to increase overall production. Any feedback appreciated.

[bcroe]

The maximum current fed to the grid is determined by the panels
and inverters. The mission of the line circuit breakers is not to
restrict system output, it is to disconnect the system from the line
in event of a fault. Of course they must be larger than the expected
current flow. Bruce Roe

[bruiserman]

Bruce, Makes sense on the breakers. Thanks. Are there any potential issues having 2 different inverters pushing the output back into the grid at the same time? Better to keep as two separate feeds or combine the two outputs or doesn't really matter? My thought is just easier to isolate the systems if need be, by keeping totally separate. Bruce Matyas (brothers from another mother lol)

[peakbagger]

I have three legal GT arrays and they play well together. The problem is that the allowable connected amperage of the three combined inverters nameplates exceed the allowable 20% of my main panel bus bars, so I could not connect them directly to the main panel. The solution was connect the three of them to a PV only subpanel protected by a breaker that is 20% of the main panel bus rating.

[bcroe]

Are there any potential issues having 2 different inverters pushing the output back into the grid at the same time? Better to keep as two separate feeds or combine the two outputs or doesn't really matter? My thought is just easier to isolate the systems if need be, by keeping totally separate. Bruce Matyas (brothers from another mother lol)

I have 2 inverters, each feeding its own double breaker into the
box. These breakers want to be located at the opposite end of
the busbar, from the Power Co feed. This guarantees it is physically
impossible for PoCo and inverter currents to add at any point on
the busbar, since they are flowing in opposite directions. Using
the 20% rule will protect you like belt and suspenders.

I think it is better to use more, smaller breakers, than one big one.
Smaller level faults can be disconnected. And the smaller current
through each will result in less heat buildup at any one spot.
Bruce Roe