Charging multiple EVs... MIC increase needed?

cros13

I'm moving back into a house (built 2006, urban area) I've had tenants in for the last few years.
I now have two electric vehicles in the household, both of which will be charging on the night rate at 32 amps each for 5-8 hours a night. Yeah.... 64 amps total.... just for the cars. This will not be the last time this issue is going to come up...

There are no electric showers and cooking/heating is gas. I'd occasionally be using a 2kW electric heater in the computer room.

Lighting etc. is all LED, appliances are all A rated or better and the base load without the EVs or heater is 300-600W.

Ideally I'd like to have 32A of spare capacity for an IEC socket in the computer room (powering a power distribution unit for a 19" rack with ~2-3kW of peak power drawn).

I reckon I'm pretty far outside ESB's usual idea of domestic load at this point.
But:

I don't have a clue what MIC to ask for.... when I add up all the loads it looks way way beyond 12kW
I'm not sure anything is a good candidate for priority switches.
I want to try to avoid paying ESB mad money in increased standing charges or for the MIC upgrade.
Ideally in the next year or so I want to add ~3kw of solar panels and 14.4kWh of batteries to this nightmare (though all connected to a single grid-tie inverter).

Also would my nightsaver rate be still available if I increased MIC too far? Would I be forced onto the industrial rate?

Would moving to three-phase be a viable option?

2011

The first exercise is to work out your entire electrical load. It would be better to measure as much of this as is possible (rather than calculate). Instruments such as a grip on ammeter can be used. I used to use old reconditioned ESB meters for this type of exercise.

When you say that the EVs draw 32A I would imagine that this is on the secondary side of the charger unit. In other words it is drawing a far lower current at mains voltage. Can you post a picture of the name plate of the charger?

In addition it is important to understand "diversity".

From this link:

When the maximum demand of a supply is being assessed it is not sufficient to simply add together the ratings of all electrical equipment that could be connected to that supply. If this is done, a figure somewhat higher than the true maximum demand will be produced. This is because it is unlikely that all the electrical equipment on a supply will be used simultaneously.

2011

This link may be of interest:

A home charge point is usually installed on an external wall of the house and electric car charging is facilitated through your domestic electricity supply. An electric car will draw single phase 16A (3.6kW) when connected to your home charge point.

cros13

2011 wrote: »

The first exercise is to work out your entire electrical load. It would be better to measure as much of this as is possible (rather than calculate). Instruments such as a grip on ammeter can be used. I used to use old reconditioned ESB meters for this type of exercise.

When you say that the EVs draw 32A I would imagine that this is on the secondary side of the charger unit. In other words it is drawing a far lower current at mains voltage. Can you post a picture of the name plate of the charger?

I use separate OWL meters on the apartment I'm currently in and both existing chargepoints. One draws 7.06kW consistently for about 3 hours then trails off for the last 10% of charging and the other draws 6.1kW for 4 hours. The issue is that both of those vehicles are being replaced this year (one this month) with vehicles with a 70 kWh and 30 kWh battery respectively (currently one of them is 22kWh with a 7.2kW rated internal charger and the other has a 24kWh pack with a 6.6kW rated charger). So the chargepoints see a demand factor of 0.98. I'm not moving my existing chargepoints as they are unsuitable physically. This is what I'm looking at:

http://www.rexelenergysolutions.co.uk/product/2500633285/Rolec-Mode-3-EV-Wall-Mounted-Charging-SecuriCharge-Dual-32amp-Type-2-IEC62196-Socket-Keyswitch

And this is a week of usage on my apartment at the moment excluding the car chargepoints (they are connected to an isolator and separate board after the meter but before the consumer unit, this OWL is on the input to the consumer unit):



That includes running the dishwasher and dryer at the same time.

2011 wrote: »

In addition it is important to understand "diversity".

From this link:

The problem I'm seeing is that the EVs will be a sustained overnight load of 13 to 14kW for up to eight hours. The extra 2-3kW from the servers and household use will be on top of that. With a little bit of headroom I assume that means needing to go from a 12kVA supply to a 26kVA supply with all the associated costs.

2011 wrote: »

This link may be of interest:

I'm afraid that only applies to ESB's "free" charge point. A lot of people these days just sell that or pay for a 32A to be fitted. The charge point is just a fancy outdoor socket with a builtin RCBO. 32A costs the same as 16A. For a typical EV 16A charging gives you 120-160km of motorway range for an eight hour overnight charge, 32A gives you double that. My commute will be just over 200km a day (far side of Laois to Dublin) plus whatever use in the evening. Plus it's nice to be able to plug in at any time during the day and get a meaningful amount of range while having dinner or whatever.

Dardania

Their schedule of rates is here, and it notes an enhanced connection of 16kVA which might be for you:

https://www.esb.ie/esbnetworks/en/commercial-downloads/ESB-Networks-Statement-of-Charges.pdf

Add onto that the cost to modify or replace your consumer unit / isolator board to be 80A + capable.

2011 is right (as usual) about considering diversity (whether that be as it happens or enforced)
Do both cars need to be at 32A? What about a 16A and a 32A = 48A which is roughly 11 or 12 kVA (don't know the power factor for those chargers)
Add on your 2kW heater and 600W base load, you're up and around 60A - the incoming supply as it stands should be at 80A...so possibly some mods required to the consumer unit / isolator board only.

cros13

I think I might go for the 12kVA to 16kVA upgrade and play it by ear. I'll also upgrade the tails for the chargepoints and computer room to 5 x 6 or 5 x 8 sq mm cable.

What's usually involved in the upgrades to the consumer unit?
How can I futureproof those upgrades if I decide to go to three-phase in the future and fit 22kW chargepoints?

Dardania

It sounds like you have a lot of needs and a lot of options to achieve them...

Presume you want to sub-meter in the new house?

There's two scenarios - single phase & three phase.

There's also the future possibility of PV to be worked in.

I think your existing strategy of having an "isolator panel" (refer to it as a main distribution panel) between the meter and the dwelling consumer unit is good. All of the heavy loads & inputs you're considering are effectively spearate to the usage of electricity within the dwelling.

So, presume a main distribution panel to be located between the meter & dwelling. This main DB needs to:

- receive ESBN power
- Distribute to dwelling
- distribute to car 1
- distribute to car 2
- in future receive PV power
- ideally have a possibility of power monitoring

This panel could go inside or outside.

If it were inside, or outside somewhere "safe", it could be something like this: http://www.meteorelectrical.com/q-din-20-mod-ip65-consumer-unit.html?cpath=827_3_145_3153

If it were outside, and not vandal safe / in direct sunlight, it could be made from something like this, with a DIN rail et al added to it: http://www.meteorelectrical.com/metal-enclosure-ip65-300x250x150-c-w-base-plate.html?cpath=827_3_145_1066

You would then terminate your ESBN supply onto an incoming breaker in it - say a 80A MCB (B curve to discriminate with what is likely to be a 80A fuse in the ESB outgoer - never fitted 16kVA supply so not sure if they do 80A or 125A)
You can make a call now if you want this breaker to be interlocked with the future PV input e.g. some trip contacts so that you can release the mains if it fails...

And then fit the required breakers for the outgoers:
- a 63A MCB (B curve) to the existing dwelling consumer unit
- a 32A RCBO (B curve) to car 1
- a 32A RCBO (B curve) to car 2
- a 16A MCB (B curve) to allow connection of your future PV input

There should be enough space in the above linked boards for the main DP such that if you go three phase in future, you can swap the breakers as necessary. 22kW @ 3 phase should still be a 32A (albeit 3 phase) RCBO...so you need 3 ways + 3 ways + 3 ways for the incomer + 2 no. cars + 1 way for the dwelling + 1 way for the PV.
I would tend to keep the dwelling at single phase unless you had a pressing need for 3 phase (e.g. fancy coffee machines etc.)

For submetering, you could meter all of those circuits if you wanted...

Make sense?

A good site to read: https://www.esb.ie/esbnetworks/en/downloads/national_code_of_practice.pdf