Home charging options

[LukeT]

I have 2 locations where I will look to install charging at better than 13A. One three-phase and the other single.

I'm sure this question has been asked many times (and I have read a few) but I'm still not quite there on my options. Am I right that they are essentially:

Tesla: Best and priciest
Limited to 7kW for “most homes” – is this an installation on single phase, where the charger runs at its theoretical maximum of 22kW on 3 phase?
Regarded as best, but why? Just for the button to flip open the charging port?

Next best thing: other wall mounted EV chargers, like Pod-point which is £359 after grant for single phase 7kW or £999 after grant for 3 phase 22kW.
What are the pros and cons for these vs Tesla and what other brands should I consider?

Cheapest: "commando" socket running 4kW on single phase or c.11kW (16Ax230Vx3) for 3 phase.

What I'm looking to understand a bit better is - what are the reasons for Tesla over the others and what are the differences between the others? If not Tesla then what do people recommend? For a given connection (3 phase vs single) they are all as near as makes no difference the same current/speed, right?

Subject to installation cost, Tesla might be fairly competitive on 3 phase even if it isn’t on single.

Both my chargers are likely to be outside (although I think I could get either under cover in the long run if it makes a difference) and used more than once a week, so I think tethered cables rather than taking them with me.

 

[WannabeOwner]

Regarded as best, but why?

Load balancing (for multiple chargers). Best as I can tell, is seems to have been reliable. Even a once-a-year failure, such that you wake up in the morning without any additional charge, is a right royal PITA ... and I get that at least once a year on Rolec both at home and at work ...

What are the pros and cons

It seems? that grant-assisted has more red tape and paperwork, and price is higher, and after grant can work out "not much different", so worth checking that (if you fancy a unit that is not grant-approved

I think tethered cables

Me too. I don't want to increase wear and tear on my, expensive, UMC cable - and I certainly don't want to be coiling it up to take with me in the rain ...

You could also fit a Commando as a fall-back. Mine flexes horribly when i put the cable in / out, so there might be more "robust" solutions to that. But there again, mine is intended as a sometime-never solution ... just it hasn't turned out quite like that.

 

[ewoodrick]

First thing to think about is how do you drive on a daily basis. That will translate into how much charging you need to do. Or you close to a Supercharger if you need to go a quick top off?

The UMC is an awesome solution, just get an extra one to leave plugged in the garage and keep the other in the car.

 

[WannabeOwner]

First thing to think about is how do you drive on a daily basis.

I recommend plugging in every night, except perhaps if you have done less than 10 miles - but then if sometimes-you-do and sometimes-you-don't you don't have a reliable plug-in-habit. Sooner or later you will have an unexpected journey, and you will appreciate having the car fully charged

Unless annual mileage is tiny, or you mostly charge at work, it is likely to be worthwhile getting an Economy-7 dual meter rate and scheduling the car for off-peak charging at home. if you have off-street parking of course

get an extra one [UMC] to leave plugged in the garage

That's likely to be a lot more cost than the tether on a wall charger, isn't it? (This is the UK forum, so we don't have the equivalent of a higher-kW socket in the garage that the US has, so our standard socket is 240V and a bit less than 3kW, and a garage-socket will just be on the ring-main and probably not a great idea to use it, repeatedly, for continuous running ... so a dedicated 7kW wall charger is better ... and then my preference is to get one that is tethered, particularly if it is outside

 

[PDB33]

Chargemaster put in a BMW Wallbox 7kW charger for a BMW i3 six months before the Model S arrived. It does well for both. It’s outside on a brick wall, open to the weather and seems fine. We have never had a failure. I completely agree about the tethered cable. It is probably not the cheapest solution.

The electricity supplier had to fit a 100A double pole isolation switch in the electricity meter cupboard before Chargemaster could complete the installation, not sure why.

Ecotricity switched us to the Economy 7 tariff and seemed to give a good deal on both daytime and night rates - maybe it’s a discount for bulk purchase.

The i3 gets charged most nights. The Model S gets charged when needed but I like the warm feeling from charging on a windy weekend night when demand is low and most of the electricity is non-fossil generated (see Gridwatch website, image below). green = nuclear, black = coal, blue = wind, red = combined cycle gas. Horizontal lines are 5 GW increments.

 

[LukeT]

My slightly odd existence involves a 200 mile each way weekly commute most weeks, and a normal amount of incidental driving either end. So I'm expecting to need to install a decent wall charger both ends.

It sounds like a good solution is a tethered wall charger with a commando socket (on the same circuit?) in reserve. And since the commando socket doesn't add much to the cost it might as well be the same both ends except that one end is single phase and the other three.

Tesla vs a third party charger though I'm not sure. Is the £460 Tesla one three phase? It's quoted as 7kW up to a max 22kW if the house allows it, so it sounds like the difference between those two examples is the phasing, but the tesla website doesn't explicitly say so and I've not seen hardware being both single and three phase compatible before.

 

[LukeT]

Another related question is re PV panels. I'm planning to install some anyway (one of the reasons I installed a 3 phase connection is it allows substantially more PV generation) but haven't yet. It awaits some roof renovation.

Taking PV generation through an inverter to AC and then taking it back to DC in a charger seems unnecessarily inefficient - are there other solutions I should be aware of in this regard? I hadn't intended to fit a battery, although I could.

 

[arg]

Tesla vs a third party charger though I'm not sure. Is the £460 Tesla one three phase? It's quoted as 7kW up to a max 22kW if the house allows it, so it sounds like the difference between those two examples is the phasing, but the tesla website doesn't explicitly say so and I've not seen hardware being both single and three phase compatible before.

Yes, the Tesla WC is only supplied as the three-phase capable model, so you get 22kW out of it if you wire it to a three-phase supply, 7kW if you only wire one of the phases. It used to be available in two cable lengths, not sure if the short version is still available.

The button on the cable and decent aesthetics, plus power sharing and three-phase if you can make use of them, are advantages of the Tesla WC. Disadvantages are that they haven't updated it for latest wiring regulations so you need an expensive Type-B RCD to go with it (units from other suppliers with integral DC fault protection only need the much cheaper Type-A RCD); also as mentioned it isn't eligible for the OLEV grant.

Taking PV generation through an inverter to AC and then taking it back to DC in a charger seems unnecessarily inefficient - are there other solutions I should be aware of in this regard? I hadn't intended to fit a battery, although I could.

The fact that the PV happens to generate DC is of little relevance given it's DC at the wrong voltage and an inversion stage will be needed regardless. In theory you could skip one conversion stage by going direct from panels to charger, but there's no cost-effective solution for doing that (I have seen solutions in the $20K range that look legit, or in the $5K range that look like a shonky collection of parts with no safety approvals...). And you are only looking to save a few percent in efficiency anyhow.

The Zappi chargepoint is useful in conjunction with solar in that it can trim the car's charging rate to match solar export. However, I'm not sure if they have a three-phase model that's available and actually works. If hardware hacking is your thing, you could fit the Tesla WC and tap into the sharing data connection to achieve the same effect.

 

[LukeT]

Yes, the Tesla WC is only supplied as the three-phase capable model, so you get 22kW out of it if you wire it to a three-phase supply, 7kW if you only wire one of the phases.

Ah ha. Makes sense. In that case, among three phase units the tesla one seems reasonably competitive if installation isn't much over £500. I'll have a chat with an electrician. Anyone had it fitted three phase and have a view of costs they could share?

 

[stigmeister]

Ah ha. Makes sense. In that case, among three phase units the tesla one seems reasonably competitive if installation isn't much over £500. I'll have a chat with an electrician. Anyone had it fitted three phase and have a view of costs they could share?

Also remember that a 32A Commando in the UK will pull 8KW off a Single Phase supply.

I have a PodPoint at home at 7KW that in 2 years has been faultless. But does get expensive if you want the 3 Phase and as a result I'd be going for a Tesla installation if I had the luxury of 3 Phase. However at our holiday home in Wales I've fitted just a 32A Commando and it works really well using the UMC, which like others I try to keep in good condition by not using a great deal as it's a god send when you need it on other connections when travelling (I've used 16A single and 3 phase commando at camp sites and 13A in holiday lets etc).

Another thing to remember now is Economy 7 is being phased out in terms of the meters are generally going out of manufacture. I'm closely involved in the UK Energy Retail markets and SMETS 2 meters that will finally be rolled out rather than the disaster of SMET 1 will enable a lot of Enenrgy companies to do very interesting tariffs for EV or Battery Storage users.

Already Octopus Energy has an EV deal for existing customers that is a very competitive rate of I think 18p per kWh in the day and 4p per kWh between 12:30 and 4.30am. Which is a far better option than E7 from what I've seen in E7 rates, happy to be corrected. However I think they have stalled the roll out as they wait to switch from SMET1 to SMET2 meters as the stock of SMET1 is running low.

 

[WannabeOwner]

Octopus Energy has an EV deal for existing customers that is a very competitive rate of I think 18p per kWh in the day and 4p per kWh between 12:30 and 4.30am.

I believe Scottish Power have a 15.23p peak and 4.74p off peak rate ... and some sort of subsidised car charger thingie

Tide also have a good rate, but punitive separate evening rate ... so probably only suits people who are never home int he evening or have a battery

 

[Smiley]

I believe Scottish Power have a 15.23p peak and 4.74p off peak rate ... and some sort of subsidised car charger thingie

Tide also have a good rate, but punitive separate evening rate ... so probably only suits people who are never home int he evening or have a battery

As an existing Scottish Power customer of 15yrs, I tried to switch to this EV tariff when my last tariff was ending. They told me that as an existing customer they couldn’t offer me the EV tariff...they literally couldn’t find the tariff on their system even after I gave them the exact URL on their website. I left SP as they couldn’t offer me a decent EV worthy tariff, now with Peoples Energy who have decent tariffs for EV drivers.

 

[WannabeOwner]

as an existing customer they couldn’t offer me the EV tariff

Crazy isn't it. I was brought up "It costs 6x as much to get a new customer as to keep an existing one" the world of "Chuck away all existing customers" is mad.

 

[LukeT]

Well I didn't know there were already specific tariffs for EV users but it makes perfect sense.

My home 3 phase is a new connection on a dumb meter and a bog standard tariff for a house that's not yet finished, awaiting SMETS2 and a switch once up and running. And PV, but that's probably 6 months away. So this could all tie in rather nicely in a few months' time.

It looks like the favoured option on 3 phase is Tesla for sure, with commando alongside. Then probably a pod point or similar at work, also with commando alongside. There is actually 3 phase on the work site but I don't think it's cabled to the right building. If there is it sounds like Tesla is the way to go and forget the grant.

 

[pjuk]

now with Peoples Energy who have decent tariffs for EV drivers.

I’m currently with Peoples Energy but cannot find any information about off peak or EV rates and wondered if you can point me in the right direction. Thanks!

[edit] I should add that I don’t have an E7 meter and no idea if it’s worth (or can) even get one.

 

[WannabeOwner]

a pod point or similar at work

We're putting in Tesla at work car park, because they load-share, and because of the work place charging discount thingie (assuming we haven't missed the boat, and that is still available ... car park wiring held up by builders "not quite finished yet")

 

[Smiley]

I’m currently with Peoples Energy but cannot find any information about off peak or EV rates and wondered if you can point me in the right direction. Thanks!.

I think they only have tariff, so everyone is on the same, there isn’t an off peak option.

Below are the electric rates;

Unit rate - Any Time: 12.16381 p/kWh
Standing charge: 21.2 p/day