BDL

Hi Chris you have answered your own question as to why the factor is 1.56 and not 1.25. Like TTT says it's all in the maths. Standard calculation for a breaker is 1.25, if that is then 'derated' for a solar application by 1.25 the calculation is 1.25*1.25 = ?? The reason that we 'derate' the calculation is that unlike in a normal situation with utility power where the amps with a given power draw can be fairly accurately determined (factor of 1.25) in a solar situation the figures can be a lot more unpredictable. The Isc of a particular panel is measured at STC conditions. Especially here in SA it is not uncommon to have conditions better than STC( standard test conditions) I have seen a 330w rated panel for instance comfortably running at 345w for instance. Hence the industry recommendation of the 1.56 factor for highly variable solar applications.

Look at the frequency shifting settings. They need to be set up correctly else the system will experience problems especially if you lose the grid during a power outage and the delta inverters are not throttled back if there is excess power. Not all grid tie inverters play nicely in a AC coupled system which is islanded. We have had quite a process to get the Solaredge inverters to work with the victron in a AC coupled situation, which involved direct support from Solaredge. I don't know the delta situation first hand, but I can tell you that the settings are important for it to work correctly. Load shedding is going to be back soon and the last thing you need is for the grid to fail at 12noon on a sunny day with battery bank fully charged and low or no loads. Something will start to smoke and it most likely will be the Quattro

There is no victron mppt? Setting feed in excess solar power will have no effect in a AC coupled system with a delta grid tie inverter. Ess doesn't need the AC current sensor for operation, only useful to see the pv power on the remote console. Unlikely it will be the problem. Likely areas to look at may be the AC current input limit as this would affect power in or out, the frequency shifting settings in ess relative to the settings in the delta...