Here's what has happened. The Victron 150/60-TR SCC was faulty, has been replaced, in that it allowed a back-feeding of the panels at night. I'm not certain that was the cause of not being able to reach high power.
However, today the panels reached 1,527 w and that happened when the battery voltage was about 26.37v. My guess is timselectric was correct that the panels will provide maximum power IF the battery voltage gets low enough.