Home Charging Methods & Tariffs in the UK

[D00]

A long story, but hopefully sharing my experience will be useful to others buying their first EV and looking at home charging methods and tariffs. All of this was new to me. Please let me know if you found a better option.

Background

I recently replaced my 911 C4S with a Taycan 4S. I’d wanted a 911 since I had one on my bedroom wall as a kid. The 911 gave me memories of some great drives, but was spending more time cosseted in the garage, being used only as a treat. I wanted something more usable. If I could afford a different car for every day of the week, one of those would definitely be a naturally aspirated 911. Almost nothing beats being connected to a 911.

Home Charging Methods & Tariffs in the UK

I soon realised that while faster, public charging costs are up to 10x those of the cheapest home rate. Just to be safe, I had acquired around 8 new charge point apps and RFID cards before my first long trip in the Taycan.

After comparing the EV and day rates, and installation requirements of Octopus, EDF, British Gas and OVO, I plumped for OVO Charge Anytime. At 10p, their EV rate isn’t the cheapest, but, swings and roundabouts, most day rates are higher than OVO’s 30p - which matches the cheapest public charge rate I had found (other than secret free ones). And for some EVs, including Taycan, the OVO physical installation requirements are zero.

The cheapest EV rate is provided by Octopus Intelligence - 7.5p for a narrow 6hr overnight period. But their day rate is 40p, compared to OVO’s 30p. Also, Octopus seem to have a one size fits all charger installation requirement,where they want to run additional electric and data cables from your smart meter to one of their specific compatible chargers. I already had a 40 amp supply to my separate garage and didn’t fancy digging up the drive to lay more cables. Also, the Taycan came with the dumb Porsche Mobile Connect Charger, so I didn’t want/need to buy another charger.

The cheapest Octopus rate of 7.5p isn’t yet available to Taycan drivers, so meanwhile they’ll sell you their ‘Go’ product, with a 9.5p EV rate and a 40p day rate. British Gas wanted to fit a British Gas specific Smart Meter, despite SMETS2 meters allegedly being compatible with all suppliers.

OVO Charge Anytime (10p EV rate, 30p standard ) is a fairly new product. Unlike the others, it relies on an app and integration with a compatible Car rather than with a ‘smart’ charger. If your car isn’t compatible, a specific smart charger is required. Fortunately the Taycan is compatible - although in seeking verbal confirmation of this, their Customer Service team initially said it may not be and essentially, I had to suck it and see. I had to escalate to get the web site info confirmed before switching from EON to OVO. EON will sell you and install a charger, but don’t yet have a reduced tariff for EVs(!).

I didn’t yet have a smart meter, having resisted to avoid the possibility of supplier tie in. To avoid wait times, forums recommended getting your existing supplier rather than one with a specific EV tariff to install a smart meter before switching. The lead time for EON to install a smart meter was only 2 weeks rather than the months that other providers with in demand EV tariffs can take.

EON’s smart meter installation was smooth and despite our rural location, connectivity was instant.

Once the smart meter was installed, I switched from EON to OVO, having first paid off the outstanding EON balance to avoid any snags there. The switch to OVO was completed within 2 days and was trouble free.

The day following the switch, I downloaded and installed the OVO Charge Anytime app. This integrates with your OVO Account, your Porsche Connect/My Porsche account and another OVO/SSE system called Kaluza.

In the OVO Charge Anytime app you schedule your required charge percentage and completion time. Any profiles/timers on your Taycan will override those you instruct in the app. As the product name implies, charging can occur Anytime and isn’t necessarily restricted to a narrow overnight window. The Kaluza system will talk to your car to complete your charging instruction and arrange charging according to supplier capacity - which may not just be overnight. E.g. if you plug in at 6pm with target completion of 9am it can spread the charge across that period, at the reduced rate. If you want to override your schedule, you can set the app to start an ad-hoc urgent charge, at the 30p rather than 10p rate.

I definitely wasn’t expecting an integration across multiple systems and the car to work first time, but it just did.

I’ve not yet seen my first monthly bill with charging credit applied (the back office OVO and Kaluza systems log your EV charging hours and deduct 20p from the standard 30p unit cost). But for me this proved that with a simple 32 amp supply to a commando socket, you can use a dumb charger to charge a Taycan at 10p per unit, while still having a standard day rate, and avoiding tie in to suppliers and their specific and expensive smart chargers and installation costs. The market is young and evolving, todays ‘smart’ chargers will be overtaken.

In my case I’m using the dumb but very expensive Porsche charger, others are available for a few hundred pounds. Similarly you can get a lead to extend the Porsche one way cheaper than the £700 they charge.

Even if you can only charge with a 13amp plug, the OVO tariff may still be worthwhile.

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[Abdul]

Great write up. Thanks! I'm with octopus at present and was looking at Ovo

 

[4suser]

V useful, many thanks

 

[D00]

More:
- I understand that if you already have an incompatible smart charger, it is best to configure it in direct to vehicle mode/butt out and act dumb.
- I don’t know if/how Charge Anytime works if you have multiple EVs, but don’t have one of the ‘OVO certified chargers. There is an OVO forum with good support and a support team at [email protected]

 

[rb33gl]

I have OI and a Hypervolt charger. 7.5p for 6 hours overnight and the day rate will go down from 40p to 30p on 1 July.

Must be the cheapest out there

 

[D00]

I have OI and a Hypervolt charger. 7.5p for 6 hours overnight and the day rate will go down from 40p to 30p on 1 July.

Must be the cheapest out there

OI was the cheapest rate I found. More so if their standard cost is coming down to match the OVO rate. The OI daily rate is also cheaper than OVO’s.
It was the £900 extra set up cost, digging up my drive and running intrusive cables through/along the house that precluded Octopus for me. That and sinking money into a charger that may be incompatible with the next best rate to come along.

 

[bn8959]

One thing I thought about the OVO system, was that when it charges, you meter accumulates your use at the full rate. After the charge, the app looks at what energy ended up in the car, then deducts 20p per kWh. However it looks at the nett energy in to the battery. What you rack up on your meter make be more (+10?) due to losses etc. so overall you may be more than you expect.

 

[XKSS]

I've been on OVO anytime for about 3-4 months and you do end up with the full monthly credit back to 10p but initially they forgot to refund the VAT - this has been sorted now and they refunded all the VAT and a £10 apology credit.
For me, the OVO deal means I can plug in anytime and generally it charges straight away @ 10p/kwh linked to my included Porsche 3 pin charger. If you need a fast charge though this system might not be for you as it only gives about 2.5kw/h charge but I'm a relatively low milage driver so topping up whenever I pull up home just works for me. In future I might go to a blue commando socket to get the 7kw speed but currently no need.
Incidentally, I got 282 predicted range miles from 100% charge yesterday morning and drove a known 216 mile route to Devon - on arrival it showed 66 miles left - great accuracy

 

[D00]

One thing I thought about the OVO system, was that when it charges, you meter accumulates your use at the full rate. After the charge, the app looks at what energy ended up in the car, then deducts 20p per kWh. However it looks at the nett energy in to the battery. What you rack up on your meter make be more (+10?) due to losses etc. so overall you may be more than you expect.

Do you know that’s the calculation method, rather than just kWh supplied?
Grateful for any references
You‘re charged for any battery inefficiencies regardles?

 

[bn8959]

Do you know it compares the battery charge level before and after, rather than kWh units consumed? I’ve not seen the method described anywhere, grateful if you can share any references. Your home meter records the KWh units consumed, as normal.


Do you know that’s the calculation method, rather than just kWh supplied?
Grateful for any references

So I am connecting a few dots and making some assumptions here - so I could be completely wrong, but my thinking is as follows:

OVO's plan seems pretty unique in that is uses the Porsche API to pull information from your car using your Porsche credentials. The 10p/kwh rate only applies to charging your car, not other loads at the same time. So it works by just using a flat 30p/kwh rate on your meter, and inspecting the before and after battery charge levels when charging - so it say 'oh, I see your battery has gone up from 20kwh to 80kwh, so ill presume you've used 60kwh and credit you back 60x20p', so that energy cost you nett 10p/kwh. However, during that charging session there are coolers, fans, inverter losses etc that will also use energy, and I cant see how Ovo could measure that in order to give you an accurate credit back - its likely that if you could turn off your house completely, so you could take a meter reading before and after your charge, I suspect you will see more use on the meter than the credit you get back (in terms of nett kwh used).

However tariffs like Octopus Intelligent, changes the rate on your meter for that 6 hour window, so ALL your consumption is billed at that rate, and clearly that will be completely accurate.

Hope that makes some sense - again, I could be wrong, but only if Ovo can somehow get a reading of the actual input energy use to the car - and I don't believe the car measures that - let alone has a way to read that back via the Porsche API.

eg I have a Tesla Powerwall battery at home that has a 13kwh capacity - I know it consumes at least 15kwh to charge it from 0 to 100%.

 

[Midlifecrisis]

Octopus Intelligent, as stated above, is coming down to 30p peak rate and 7.5p for 6 hours over night for all of your power. We have had 2 cars charging and the dishwasher/washing machine on in this window. I am not sure why some people have had to dig up their drives for cabling - we haven’t done anything like that. And the Taycan is now compatible with OI with any charger. Or once you have got it set up you can disable the smart charging and just use it as a dual tariff setup. Currently works well for us

 

[rb33gl]

Octopus Intelligent, as stated above, is coming down to 30p peak rate and 7.5p for 6 hours over night for all of your power. We have had 2 cars charging and the dishwasher/washing machine on in this window. I am not sure why some people have had to dig up their drives for cabling - we haven’t done anything like that. And the Taycan is now compatible with OI with any charger. Or once you have got it set up you can disable the smart charging and just use it as a dual tariff setup. Currently works well for us

One thing I have noticed with OI is when I plug in the car (as I did this evening at about 10) it starts charging within about 5 minutes or so. OI is supposed to detect this and sends you a charging schedule on the App. But then it keeps on charging, even though it's outside the 6 hour cheaper rate window. I think this has something to do with the monitoring software - it only reads meter data every half an hour.

Octopus say any charge that is not a 'bump charge' (where you can override the charging schedule) is at the cheap rate.

We've only just moved over to OI, so I intend to get some clarification about this from Octopus over the next week.

 

[D00]

Octopus Intelligent, as stated above, is coming down to 30p peak rate and 7.5p for 6 hours over night for all of your power. We have had 2 cars charging and the dishwasher/washing machine on in this window. I am not sure why some people have had to dig up their drives for cabling - we haven’t done anything like that. And the Taycan is now compatible with OI with any charger. Or once you have got it set up you can disable the smart charging and just use it as a dual tariff setup. Currently works well for us

Checking again today, the Octopus charger compatibility list still does not include the Porsche supplied charger. Octopus advised that I could get OI only if I installled a new compatible charger, with new electric and data cables from the smart meter to my detached garage. I already have an appropriate electric cable laid to the garage, but they wanted to lay another electric cable, a data cable and sell me another charger. For me the £1500+ cost, mess and disturbance from that, for a 2.5p per unit saving, wasn’t worth it. OVO uses the car’s existing data connectivity and my existing electric supply, in comparison, set up was a breeze.
[

 

[D00]

So I am connecting a few dots and making some assumptions here - so I could be completely wrong, but my thinking is as follows:

OVO's plan seems pretty unique in that is uses the Porsche API to pull information from your car using your Porsche credentials. The 10p/kwh rate only applies to charging your car, not other loads at the same time. So it works by just using a flat 30p/kwh rate on your meter, and inspecting the before and after battery charge levels when charging - so it say 'oh, I see your battery has gone up from 20kwh to 80kwh, so ill presume you've used 60kwh and credit you back 60x20p', so that energy cost you nett 10p/kwh. However, during that charging session there are coolers, fans, inverter losses etc that will also use energy, and I cant see how Ovo could measure that in order to give you an accurate credit back - its likely that if you could turn off your house completely, so you could take a meter reading before and after your charge, I suspect you will see more use on the meter than the credit you get back (in terms of nett kwh used).

However tariffs like Octopus Intelligent, changes the rate on your meter for that 6 hour window, so ALL your consumption is billed at that rate, and clearly that will be completely accurate.

Hope that makes some sense - again, I could be wrong, but only if Ovo can somehow get a reading of the actual input energy use to the car - and I don't believe the car measures that - let alone has a way to read that back via the Porsche API.

eg I have a Tesla Powerwall battery at home that has a 13kwh capacity - I know it consumes at least 15kwh to charge it from 0 to 100%.

I think your assumptions are probably invalid. The Porsche account credentials are probably used only during initial set up, to record the car’s credentials and connectivity. I don’t think the Porsche API is used thereafter. An execution dependency on a 3rd party potentially unavailable API would be daft.


On whether the car’s data regarding before and after battery capacity levels, or charging units is used towards billing, your guess is as good as mine. Charging is split across multiple sessions according to grid availability, so the central system will always need a record of individual figures per session. If I was designing this, to avoid loss of data as a result of disconnection, I’d use the most granular data available. In some circumstances the car‘s units consumed are written to your My Porsche account. The detail of how it actually works may be withheld for commercial reasons, I couldn’t find anything on OVO or Kaluza web sites.

Your point regarding charging kWh being greater than capacity kWh would be true for all energy suppliers, not just OVO Charge Anytime.

 

[Midlifecrisis]

Checking again today, the Octopus charger compatibility list still does not include the Porsche supplied charger. Octopus advised that I could get OI only if I installled a new compatible charger, with new electric and data cables from the smart meter to my detached garage. I already have an appropriate electric cable laid to the garage, but they wanted to lay another electric cable, a data cable and sell me another charger. For me the £1500+ cost, mess and disturbance from that, for a 2.5p per unit saving, wasn’t worth it. OVO uses the car’s existing data connectivity and my existing electric supply, in comparison, set up was a breeze.
[

How odd. We registered my wife’s Evoque hybrid and just said we didn’t have any of their listed chargers. It worked with no issues. We don’t use the intelligent charging because it doesn’t take account of our house battery / solar system. But there was no issue registering the car with a test charge using my supplied Porsche charger running off a 13A socket. We have no extra data cables etc.

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