EV Charging Point- Should I utilise another phase of my incoming supply

[FozzieBear]

I am looking for views and advice on installing an EV charging point. I will get an electrician or company to install it but it but wanted thoughts on the best installation method.
I have a three phase supply to my house and recently had a three phase smart meter fitted and the mains fuses upgraded by UK Power Networks to 80 Amp.
the setup is as follows:-
a. One phase from the meter feeds the house 24 way MK consumer on a 25mm three core wire armour. (There are no spare ways left on the consumer unit)
b. In addition all three phases are connected to a seperate 4 core 2.5mm cable to the garage via an MEM 3 phase breaker with 15 amp fuses. (I have a lathe with three phase motor in garage).
c. Finally I have a 10mm three core wire armoured cable from the consumer unit via a 45 amp MCB to the garage providing a single phase supply for general power lights etc.

As i see it I have two options:-
1) If the single phase supply to the garage is suitable can I get a 7Kw EV charger connected to that. I would have to get the 4 way consumer unit in the garage changed to provide a space for a 40amp? MCB; Or
2) If I am prepared to dig a trench up my driveway from the external electricity meter cupboard and bury an appropriately sized wire armour cable to the garage, could they take a supply from another phase on the meter? There would obviously need to be space to install a single phase fused breaker in the cabinet. This would hopefully allow me to have a higher rate 22Kw EV charger?

Have I thought this through properly?

 

[ericmark]

1) Not all EV's can use three phase, the local 22 kW charge point often only has a 7 kW charge as car can't take 3 phases.
2) If it can take 3 phases the system used to protect from loss of PEN can be a lot simpler, so there is a good safety reason for using 3 phase.

But the main consideration has to be based on your car, if you are getting a Citroen Ami then no point having three phase, in fact a simple 16 amp socket is enough. But no point is split phase, either single phase or three phase. As cars don't use split phase charging, they are either single phase, three phase, or DC.

 

[flameport]

1 is an option, provided the other loads are not significant. It will limit you to 7kW charging, but that is what the majority of vehicles today can use.

Replacing the 3 phase cable to the garage with a larger one would allow a 3 phase EVSE to be installed.
It will still work with any vehicle, most will only use one phase / 7kW, but would allow those vehicles that have the capability to use 2 or 3 of the phases for charging up to 22kW.
Also consider whether being able to charge the vehicle mush faster is really of value - at a home location it probably isn't as it will be parked there for hours / overnight / all day anyway.

The cost difference between a single phase EVSE and a 3 phase EVSE is trivial.
Really depends on whether you want to dig up the driveway or not.

 

[Adam_151]

2) If I am prepared to dig a trench up my driveway from the external electricity meter cupboard and bury an appropriately sized wire armour cable to the garage, could they take a supply from another phase on the meter? There would obviously need to be space to install a single phase fused breaker in the cabinet. This would hopefully allow me to have a higher rate 22Kw EV charger?

A 22kw charger will need all three phases (note what flameport says about not all vehicles being able to make use of all phases)

22kw - 32A three phase
7kw - 32A single phase

11kw - 16A three phase
3.5kw - 16A single phase

If you want a 22kw charger, then best solution would be to ditch both the existing SP submain and lathe supplies to the garage and install a new three phase supply off a 63A switchfuse and feed everything from a new TPN board

 

[Agile]

If you already have the 45 amp single phase to the garage then unless you have very powerful lights indeed you should have adequate capacity for a 7 kW charger.

Battery life is usually considered longer if it is not charged at a very high rate ( and temperature ).

An overnight charge of about 70 kWh may well be totally adequate but it all depends on the car and the daily mileage.
You have not said if you are able to get a reduced cost for power consumed during the night. But then even if you do you have to consider if the saving would be worth using a faster charge rate which might produce a shorter battery life.

But it all depends on the daily mileage you plan to do. And if you have any charging facility at anywhere that you regularly visit.

Using the existing 45 amp supply means that you could always upgrade the supply in the future if you find a 7 kW charger inadequate for your mileage.

I am not familiar with in car charging control and I would have expected most would seek to reduce the charging rate if the battery became too hot. Unfortunately there seem to be few people with much experience of electric cars and particularly not of various different models. It would be nice to see a comparative list of how the different models control charging. The Tesla seems to power a fan to cool the battery!

 

[FozzieBear]

Firstly thank you all for responding. There are some good suggestions and some very valid points made in your responses.

The problem is we don't yet know which car we want yet although the VW ID3 which has a 58KWh battery seems to fit our bill, However we wanted to future proof the install incase we decided to go for an entry model Tesla which I believe needs a bigger charger.

Normally we only do fairly short journeys of up to 20 miles or so except when we go for breaks in the UK, but then we would have to plan the journey to include stops for charging. None of the current destinations have public EV chargers. This includes supermarkets who seem to be lagging behind the curve in offering charging to customers. Therefore the majority of charging would be done at home overnight.

The added complication is that I am considering Solar Panels on the garage roof. The "garage" is actually a single storey barn used as my workshop about 30 ft (9m) long so I could potentially get 14 panels on it so about 3Kw array. I could also get an EV charger as part of this solar install but assume the EV charger output would depend on the battery size? Also I am with Octopus Energy who currently do an EV night time tariff.
As you can see there are multiple factors to consider!! However after the advice above I think the best option is to install a single phase charger on the existing 45 amp garage supply. If I go for Solar then hopefully this can be connected to the battery storage assuming I do some research on the charger make and type I fit. If I find I need to upgrade then as Adam_151 says, the best option would to be to run a new three phase supply to the garage and disconnect the existing single phase supply. Anyone know of a compact 63 amp three phase switch fuse??
Many thanks for the suggestions it is much appreciated.
Fozzie

 

[flameport]

entry model Tesla which I believe needs a bigger charger.

No EVs 'need' a bigger charger.
They can all charge from the single phase 7kW versions, and even from the 2kW 'granny lead' plugged into a 13A outlet.

t assume the EV charger output would depend on the battery size

No.

if you have solar, and a suitable ESVE such as this one, then it can be set so the vehicle only charges when solar power is available, or it can be set to charge at a low power continuously and increase that power to match whatever solar power is available.
The exact vehicle, battery size, state of charge and everything else is irrelevant.

People change their vehicles far more often than they change the installed charging facilities.

VW ID3 which has a 58KWh battery

That will take about 10 hours to fully charge from 0% to 100% on 7kW.
However that isn't realistic, as arriving home every day with 1 mile of range left and then charging to 100% to once again use all of that range the following day simply doesn't happen.

Normally we only do fairly short journeys of up to 20 miles or so

which is exactly the point - charging for a moderate amount of time every few days or so, or whenever convenient such as when the car is at home in the daytime and you have plenty of solar power available.
It's about 1 hour per day, or a few hours every few days.

14 panels on it so about 3Kw array.

If that's all you can get from 14 panels, then the panels must be tiny, or were manufactured over a decade ago.
Modern panels are typically 400W+ each, which would be around 5.6kW for 14 of them.

 

[FozzieBear]

Thank you flameport. To clarify a few points you made

No EVs 'need' a bigger charger.
They can all charge from the single phase 7kW versions, and even from the 2kW 'granny lead' plugged into a 13A outlet.

I appreciate that you can charge any EV from any charger but larger EVs like the Tesla have much bigger batteries so the charge period from a smaller output charger would mean it didn't reach the 80% charge in 9 hours which I believe is the benchmark?

No.

if you have solar, and a suitable ESVE such as this one, then it can be set so the vehicle only charges when solar power is available, or it can be set to charge at a low power continuously and increase that power to match whatever solar power is available.
The exact vehicle, battery size, state of charge and everything else is irrelevant.

People change their vehicles far more often than they change the installed charging facilities.

I think perhaps you misunderstood my post. I was referring to charger sizing being dependant on the solar storage batteries not the car battery

If that's all you can get from 14 panels, then the panels must be tiny, or were manufactured over a decade ago.
Modern panels are typically 400W+ each, which would be around 5.6kW for 14 of them.

I appreciate that panels provide 400 watts in fact the ones I would prefer to go for are N-Type IBC panels like Sunpower or Longi-Solar which are 440w. I was taking the 3Kw from a website here The table toward the bottom of the page states 3Kw for 14 panel array, but after your comment and reading it again the site appears to be out of date as they are using figures of 175-200 watts per panel so you are correct that the output should be higher.

Thank you again for your input.
Fozzie

 

[flameport]

but larger EVs like the Tesla have much bigger batteries

They do, and charging from totally empty would take a long time.
However 99% of the time, you won't be charging from empty to 100% or anywhere near that.
Even if you did need 10+ hours to charge to 100% occasionally, so what. How long it takes makes no difference to anything.

For occasional longer journeys, it just means a tiny amount of planning so that you can start that journey at 100%. That could mean charging overnight for 2 nights in a row, or possibly a brief stop at a rapid DC charger a day or two beforehand and then use the home charge to top up to that 100%.

The whole point of EVs is that you charge them when you can, not when the battery is depleted. EVs are not petrol cars and are not used in the same way (as in drive to a filling place when empty and ram as much fuel as possible in there).

It's not necessary or desirable to charge to any particular level before driving, all that matters is the charge is sufficient for the journey you intend to make, or you have planned appropriate charging stop(s) for longer journeys.
Batteries won't be damaged by part charging or partial use, despite what some propaganda outlets might claim.

A lot of information out there places massive emphasis on how long charging takes. For most of the time, it's totally irrelevant.
There are use cases where it can be important such as taxi drivers, but those are very far from typical.

I was taking the 3Kw from a website

That is many years out of date and should be ignored.
Some examples of what is available today: https://midsummerwholesale.co.uk/buy/qcell-solar

For home storage batteries with solar, the usual deal is that they are sized so that for a good percentage of the year, solar generation during the day is sufficient to run the normal items in the home, plus enough to charge the batteries so that during the evening/night those batteries can run the items in the home. That avoids importing grid power and is the lowest cost of operation.

Batteries sized depending on the energy used in the home on a typical evening/night.
It should be the case that 80%+ of the battery capacity is used every day - otherwise you have paid for capacity which isn't needed.

The solar is better being significantly oversized, so that it can provide most of the energy required for most of the year rather than just a couple of months in the summer.

While it's possible to store energy in batteries and then transfer it into an electric vehicle, that isn't the primary use case, as if the car is there during the day it's easier to just charge the car directly from the solar. It might be valid for a situation where the vehicle is rarely there in the day but is usually there at night, and also did high mileage most days. However for that there is also the option of cheaper grid electricity overnight.