Sunny Island split phase setup stopped charging from L2

[DougK]

My quad split phase Sunny Island setup stopped using L2 from grid to charge the batteries. The setup still supplies 240VAC, but the batteries will only charge from one phase (L1). There are no fault codes that I can find. Any ideas? TIA.

 

[DougK]

Found it! Turns out it was a breaker in the grid feed that was partially de-activated by a generator breaker interlock mechanism in a small QO panel. Even tho the inverters had voltage on both L1 and L2, the L2 phase was slightly flaky. Didn't show up on a voltmeter or even on an oscilloscope at the feeds to the inverters. The only indication was that the SI display was showing an intermittent * indicating "Status of the external source". I was checking for a potentially loose wire connections in breakers on any of the installation and ran across the flaky interlock setting effect on the breaker. After repositioning the interlock and making sure the breaker was totally on, everything started working again! Weird problem. Cheap interlock.