South Field PV project update 3/24/19

About 50 panels are fed from the "new garage" through a ~200' run of aluminum wire that was intended, 30 years ago, to carry 50 amps.   I'm seeing up to about 7kw from those panels.  At those peaks, the voltage rises to 260+v and causes some inverters to shut down.  Apparently due to insufficient capacity of that aluminum wire as well, perhaps, due to insufficiency of the supply to my main breaker panel.  The 50 panels should be capable of producing about 10kw which should match the 50 amp capacity I expected.  As it is, I start having trouble below 7kw or about 30 amps.

I am exploring the possibility of adding another 100 amp wire to the new garage.  Maybe a total of about 30kw.

Update 3/27/19:
A BlueBonnet guy came by today to discuss service upgrade.  He confirmed my suspicion that, ~30 years ago when I upgraded from 100 amp to 200 amp service, the transformer and supply wire was not likely upgraded.  He said my service wire looked like 4 ga.  That size aluminum will handle only about 55 amps at reasonable temperatures.  He said in a month or so that they would set another pole at my chain link fence to hold a new transformer and support heavier wire.  The current transformer is likely 15kva; a new one will probably be 25kva.  New aluminum supply will be 2/0 or 4/0; I don't recall which he said.  2/0 should do about 110 amps and 4/0 about 150 amps.  In addition, the wire run from the transformer to the service entrance will be only about half what it is now.
Bottom line: most of my trouble IS likely due to insufficient service and the problems will almost certainly disappear when BlueBonnet does the upgrade in a month or two.
If I can only push ~50-60 amps into the grid, that is only  ~12kw.  VERY close to where I encounter trouble.  After upgrade, I hope to do 50+ kw!

I asked about a lower voltage supply but he was non-committal.  Lower voltage, say 235-240 v, would give me more head room before inverters shut down.  Current static voltage is about 245.

Update 4/2/19
BlueBonnet contractor came out and cut trees to clear a path for the new supply line.  I hope the upgrade is only a week or so away.

I've recently added 12 more panels to the South Field.  They are near useless to me until the upgrade happens.