UK Do I need three phase or not? Your advice appreciated.

[pc1966]

So this setup is going to be needed more and more often as we approach 2030.

Load management over the whole system is going to be needed as well, so CT limiting and central reporting/control will, I suspect, become a requirement for any fast charger.

Basically you can have 100+ houses on a 500kVA substation as the normal usage patterns (diversity of load use) means it is not overloaded for any significant time. But the old 'normal' did not include several 7kVA chargers (or more) running for many hours simultaneously on half of the properties!

 

[Spinball]

Load management over the whole system is going to be needed as well, so CT limiting and central reporting/control will, I suspect, become a requirement for any fast charger.

Basically you can have 100+ houses on a 500kVA substation as the normal usage patterns (diversity of load use) means it is not overloaded for any significant time. But the old 'normal' did not include several 7kVA chargers (or more) running for many hours simultaneously on half of the properties!

If those houses have solar, then maybe it won't be so bad, and my plan is to be as 'off grid' as possible with mine, but that doesn't mean that I won't want to charge everything up at some point.

 

[pc1966]

I'm asking you guys as I have no clue what the procedures are for upgrading to 3-phase and I'm an optimist. Don't beat me up for that

3-phase is good for many reasons, just not cheap!

As mentioned above, the assumption for getting 3P in the UK is high load, so you might find it becomes limited due to the local substation's capacity.

I think some EU countries traditionally had 3P to homes but at much lower currents (e.g. 30A per phase) so similar total power to our 100A but more efficient cable use (but more expensive DB/meter/etc). @Lucien Nunes has much more knowledge of that aspect!

 

[pc1966]

If those houses have solar, then maybe it won't be so bad,

Not much use for over-night charging!

and my plan is to be as 'off grid' as possible with mine, but that doesn't mean that I won't want to charge everything up at some point.

It is a good goal, though if you really want to be able to operate in "island mode" (i.e. without grid power at all, even if just during storm damage) there are other concerns.

Mainly you need your own means of earthing (as the DNO's earth cannot be assumed if outage due cables damaged) and also your installation then needs to be able to disconnect on your own earth, which typically means RCD protection on every circuit, as few earth rods are low enough in impedance to allow over-current disconnection like the DNO supply earth normally enables.

Also it means your inverter has to be designed to operate without grid power (not the norm in solar as I think most shut down if grid is lost), and you must have a suitable relay to prevent any power being back-fed in to the faulted grid and possibly killing a DNO worker trying to repair things (a reason for them normally shutting down, along with what might happen when power is restored and maybe not in-phase with the inverter output).

 

[pc1966]

One last thing - if you get anything done by the DNO, unlooping or 3-phase - get an isolator switch fitted at the same time.

Not only will it make any future work on your system easier and quicker, but should you get a PV/battery system that is capable of island mode operations you can test it by switching off the DNO supply for a couple of hours to see that it works, and keeps working on restoring the power...

Test both night and day times, just to be sure PV charging work in island mode and that it still behaves on battery alone, etc.