I am available for custom hardware/firmware development
With the current matching the two strings so closely, either everything is OK, or the two strings have identical problems (unlikely, but possible).So is all working OK for you now? 10+ years on a central GT inverter is not bad--I would be saving money for a replacement (electronics last about 10+ years, and units over ~5 years old are difficult to get repaired / find replacement parts).-Bill
Keep in mind that a grid-tie inverter needs to see a low impedance to the grid. Too high and and it won't start inverting.