Exactly @lxonline
I haven’t seen any suggestion so far that the panel array has been commissioned or recommissioned; Checking Voc is not the same. Kudos to those suggesting focusing on getting a clamp or similar to check current.
I would strongly suspect that there is a fault in the array, and that measuring the array Voc is misleading you. An array can easily have an active fault (poor connection, faulty breaker, faulty panel) and still produce an apparently correct Voc. This Voc will collapse to either zero or battery voltage as soon as power is (tried to be) drawn. This seems to be exactly what OP is seeing.
My advice would be for the OP to follow this method, recommission the array. My bet is that either this finds the fault, or it rules out the array and you can move on with confidence to downstream parts of the system.