Sounds like you're in a different market. We have Sunny Islands being liquidated due to DC Solar bankruptcy (they got US $1 billion investment and bought lots of hardware.) If you have to pay retail, three Sunny Island would be $12k to $15k.
Yes, I'm in rural New Zealand. Typically one can buy stuff at recommended retail pricing (RRP) if it is on sale.
Rotary 3-phase converter? Kick over a 3-phase motor and connect it to single-phase, then connect your mill? Add more capacitors to a VFD? PV direct to VFD rail (or maybe through an MPPT regulator)? Have to watch max voltage of caps. A PWM regulator, or connect to caps through diodes (typical VFD front end) and short out PV whenever voltage rises above a threshold?
I had the CNC working on a 3-phase rotary converter at my previous house, but I couldn't take it with me. The mains connection at my new place is only 63A and the rotary phase converter needs a 60A circuit, so that is a problem. Buying a new one of reasonable quality is still more than solar inverters and a battery anyway. A VFD is basically the front end of an inverter without the low-pass filter on the output and no support for unbalanced loads and should only be used for a single motor or resistive load. Multiple loads would be a recipe for disaster. I don't like disasters, especially when they destroy my toys (and potentially invalidate my insurance).
In an ideal world, I would get an ultra-efficient, ultra-reliable 20KW 3-phase unit to run both the workshop and house and balance the house loads over the three phases. However, power export[1] to a single-phase grid isn't an option on any of the 3-phase hybrid inverters that I've seen (they all require a 3-phase grid). In addition, the house is only single phase, so that would require a rewire to balance the load. So, single phase it is. The single-phase hybrid inverters that I have found so far typically are limited 8KW max. AC power and around the same for solar[2]. I'll have almost 14KW of solar power, so I would need two single-phase hybrid inverters in parallel to handle the full PV power (my max export power is 10KW, so an PV power is the limiting factor here).
Back to the three-phase portion. I can use an off-grid 3-phase inverter and run off of the batteries or use three single-phase inverters paralleled for 3-phase. Since getting repair parts may take weeks and learning two different inverters is twice the work, my preference[3] is to use the same hybrid inverter that I use for the house for the 3-phase (just running in off-grid mode). That way, if there is a failure on the house system, I can swap over parts from the workshop system and just not use the workshop equipment instead of telling the family not to do something. I might be able to get a deal for 5x inverters as well, but that's just icing on the cake.
[1] This assumes I can get the spot power export, otherwise I'll get $0.08/KWh for power exported and pay $0.27/KWh for power used during the day and $0.18/KWh for power used at night. At $0.08/KWh for export, I would be better off storing the power and only topping up the batteries at night.
[2] Note that I am excluding anything that uses > 48V battery systems since anything higher could be declared as high risk and the entire DC system needs to be inspected and verified and I'm not allowed to do any work on it.
[3] The idle power of the inverters and extra wiring may cause the parallel approach to be undesirable