You might need some Nodoze as well 
Ordinarily I’d agree. Hindsight is 20:20 and all that.
But I have what I have and there are various historical reasons including the power distributor wrangling I had to go through to get approval to build the second dwelling for my elderly mother, (who sadly passed away earlier this year). They required two things:
- the second dwelling also have 3-phase supply
- the entire property be capped to 32 A/phase
The whole thing grew out of the fact we average a dozen longer grid outages a year on average. I kept records of them all for years. Plus all the countless short duration outages.
With just the two of us here, I previously managed longer outages with a generator, a power inlet and the transfer switch and it was a reasonable effective way to deal with it.
But with the new dwelling for my mum (which I now refer to as the studio) and my work from home wife not being able to move/operate the generator, if I was not here then they would be without power and that was not acceptable to me. Aside from my wife’s work, it can get very hot here and heat can kill the elderly and that wasn’t going to happen on my watch. My mum in her twilight years was going to have the safety and power security she deserved.
So I set up an off-grid PV/battery system to replace the role of the generator. I found it worked very well and could be automated to do a whole lot more, so I expanded it.
And it works really well so why change it? I might even add more PV and battery to it but for now it does a great job. 10 kWh of LiFePO4 for daily cycling duties, 20 kWh of sealed lead acid data centre backup batteries in reserve for those extended power outages and we are not getting left hanging.
I had hoped the fact the outbuildings had three active wires each would enable some level of circuit level monitoring for the two outbuildings as effectively I have three individual circuits going to them.
But maybe the answer is to put it all ESSENTIAL circuits on BLUE phase, including running the outbuildings via BLUE only.
It would be possible. But would it be wise? I’ll have to think that one through.
Let me have a go. I am butchering a transfer switch wiring diagram.
Here is a 3-phase transfer switch diagram to show the way ESSENTIAL loads circuits are supplied:
And some photos. Under the transfer switch (ignore the 3-pole switch on the left - that’s the main supply breaker):
And from the top:
When switch is UP (GRID SUPPLY) then the grid supply is fed through to ESSENTIAL loads via R, W, B (shown on the actual switch as R, S, T) and all circuits operate as a regular 3-phase supply.
When the switch is down (OFF-GRID SUPPLY), then the single phase OFF-GRID supply is fed through to ESSENTIAL loads via G1, G2, G3, which are linked.
Naturally when the switch is in the middle position then neither supply is connected (break before make).
Now to make things fun, the off-grid inverter can generate its own power (using solar PV and/or battery), or it can pass through GRID power coming from the BLUE phase.
Naturally the circuit feeding the AC input for the off-grid inverter is one of the NON-ESSENTIAL circuits not supplied via the transfer switch (else I would have nasty feedback loops).
My “normal” mode of operation is for the transfer switch to be left in the down OFF-GRID position.
This means ESSENTIAL LOADS, which include the Studio 3-pole breaker plus this panel which also includes the Mancave 3-pole breaker:
are all getting a single phase supply via the off-grid inverter, be it grid power passed through the off-grid inverter, or power supplied by the off-grid inverter from the off-grid PV and battery.
I hope that all makes a bit more sense.