Hi, I have an installation with an 8kw Quattro and a 3kw Fronius AC coupled. 30kw of BYD Premium LVL. Also has 5kw solar on MPPT.
The Quattro shifts the frequency as expected when the battery is full, but doesn't drop it back to 50htz when the sun goes down. In some cases it drops it back at 2 or 3 am, and in the case of the attached PDF, it held it up until 6.50am the next day. Note the battery is down to 83%SOC. Freq graphs.pdf