Octopus Intelligent Go - is it always cost effective?

Lady_Antonia

I recently leased an EV (Mini Cooper SE) through Octopus, and they have offered me their Octopus Go (EV saver) tariff: 6.6p per kWh from 11.30pm to 5.30am, 36.91p per kWh from 5.30am to 11.30pm, with a 47.47p daily standing charge.

My current tariff is an Octopus dual-fuel all-day rate of 21.84p per kWh + 41.59p daily standing charge – fixed until December. Only my water & central heating are gas, everything else is electric.

Over the last 12 months, I’ve used 1293 kWh/ £305 + £174 standing charge, and my account is always well in credit.

I am unlikely to use my EV more than a couple of times a week, driving far less than 50 miles per week so will not need to charge it more often than every 7-10 days. I work from home so almost all my energy is used during the day – it is a sole-occupancy property.

Is it worth me changing tariffs?

Also, I have a 3-pin ‘granny charger’ and have used Octopus’ free electricity periods to charge the EV for two hours at a time, which gives me about 15kWh.

As part of the 3-year lease deal, Octopus have provided public charging credit and a discount card to use at public chargers. Octopus cannot install a home charger for me due to the layout of the property and the quote I’ve had from a local company for a home charger installation (utilising the existing equipment) is £1782.

Is it worth me getting a charger installed at home?

I've tried all the maths and have ended up very confused!

QrizB

Is it worth me changing tariffs?

Probably. See maths below.

Is it worth me getting a charger installed at home?

Probably not, unless it's free or extremely cheap.

I've tried all the maths and have ended up very confused!

If you're driving 50 miles a week, 2500 miles a year, you're a very low mileage driver. You're probably only going to put 800kWh of electricity into your car a year.

Your current electricity fix is ending soon. Energy prices have risen and it's likely that any new fix will be around 28p/kWh. 800kWh of electricity at 28p/kWh is £224/yr. If you instead take the IOG fix, your 800kWh will cost £53 per year. This is a saving of £171 per year.

However, switching will mean that you'll be paying more for your household electricity. At 28p/kWh, 1300kWh will cost £364. On IOG, worst case you'll use all 1300kWh at he peak cost of 36.91p/kWh which would be £480. That's £116 more than a single-rate tariff, which would reduce your saving to £55 a year.

So the IOG deal should save you at least £55 a year. If you can move some of your household use into the 2330-0530 off-peak period, you'll save a bit more than that.

Fitting a home charger might save you 10% vs. your current granny charger, simply because fast charging involves lower losses. However 10% of the £53 annual charging cost is only £5.30 a year. Typically, home charger installation costs around £1000 so it'll take almost 200 years to pay for itself.

Alnat1

Do you have a hot water tank or is it a combi boiler? If it's a tank it would probably be cheaper to heat overnight using the immersion rather than gas if you choose the Go tariff.

Reed_Richards

I have been driving my EV for 3 years now; I charge it overnight using a "granny charger" for the 6-hour cheap period. That has worked fine for me, even though I average about 8000 miles per year. Just make sure that the socket you plug the granny charger into is suitably wired. I use an outdoor socket on a 40A fused spur to my garage that was installed 7 years ago, so I am confident in that.

Lady_Antonia

https://forums.moneysavingexpert.com/discussion/comment/82165574#Comment_82165574

Now that is an interesting idea! I have a hot water tank and don't use much hot water each day. Dishwasher goes on once a week, overnight, and the few left-over bits, washed up in a bowl once a week. I prefer a bath to a shower and, again, tends to be once a week with a stand-up wash at the sink each morning (please don't judge me!!). Thanks for this suggestion - sounds ideal with an overnight tariff.

Lady_Antonia

https://forums.moneysavingexpert.com/discussion/comment/82165588#Comment_82165588

I would be happy to do this too, although I'd be concerned if the weather was wet or very cold, outside wires and all that?

Lady_Antonia

https://forums.moneysavingexpert.com/discussion/comment/82165562#Comment_82165562

Thank you for checking my maths - never my strongest subject!

So, there would be savings even if not earth-shattering ones. Alnat1's suggestion for the immersion heater is well-worth considering and I already use the dishwasher overnight. I'm not sure I have a timer on my washing machine but an hour's use every 2 or 3 weeks won't break the bank. My PC is on all day, everyday, and my oven and hob are electric… and of course, there's the kettle! Your calculations, however, indicate that I'd still be saving in any event.

I think I'll stick with the granny charger and public EV points - I thought the home charger would save me more but it seems negligible.

Thank you so much for your advice. My head was spinning before!

Reed_Richards

https://forums.moneysavingexpert.com/discussion/comment/82165607#Comment_82165607

Copper wires don't mind cold temperatures at all. And an outdoor socket and granny charger are both engineered to be rainproof.

MWT

https://forums.moneysavingexpert.com/discussion/comment/82165783#Comment_82165783

Do check the IP rating on the specific device as they vary, also 'rainproof' doesn't mean you can leave it in a puddle…