DANGER! DANGER! (pause) HIGH VOLTAGE! etc

One would think that in Britain at the height of an energy price crisis that switching to a pure electric vehicle might be a silly move. But you’d be missing the fact that lead times on ordering new electric vehicles have been up around the 18-month mark, meaning that when we ordered it we weren’t in an energy price crisis.^[i]Moreover, I genuinely believe it’s a sound move to go to a situationally-emissionless EV rather than driving around suburbia in a diesel car. Plus, this thing goes like the fucking clappers.

ANYWAY, all this led to me wondering whether we’d benefit from switching electricity tariff over to the Octopus Go tariff for EV owners, which delivers low-priced electricity from half-past midnight to 4:30am so that you can charge your EV when demand on the grid’s lower.

Luckily, we’re already with Octopus^[ii]At this point I need to enthuse about Octopus being the best energy company I’ve ever had an arrangement with – we’ve had ZERO trouble with them so far, and they proactively offer … Continue reading – which means that we can take advantage of their EXCELLENT public API’s to examine this sort of thing.

DOUBLE-luckily, the incredibly lovely Guy Lipman has written a bunch of cool stuff on how to use the Octopus Energy API – and my jumping off point for this was the read-only Google Sheet he’s written which you take a copy of, then fill in your API credentials and it goes off and fetches the data.^[iii]I started off cobbling together some PHP to make these calls (and may still persist yet) but then concluded as it was all going to end up in a spreadsheet anyway, why get a dog and then do my own … Continue reading

Step 1 was to understand the general shape of our power use – so hitting https://api.octopus.energy/v1/electricity-meter-points/{my number}/meters/{my meter}/consumption/?page_size=1000 we get the last 1000 half-hourly recorded consumption points.

From there a few Sheets formulas did the aggregating & pivoting so I could convince it to graph the thing – which, I think you’ll all agree, has proven totally worthwhile.

We can see – surprise, surprise – that we use more electricity between 6am and 9:30pm than other times. You can also see the couple of times we plugged the EV in to charge (and how one time it finished charging around 3am, whereas the other time it kept slurping away).

Obvs, we’d get a clearer picture with some “control days” to understand what putting the kettle on looks like, or the dishwasher, the oven, or the washing machine (I think those are the main ones). And a day where we’re not in so we can see what the “basic load” looks like (all the various things we – probably irresponsibly – leave plugged in or on standby all the time).

The next bit’s harder (and even less interesting) to show, but I was able to bash more formulae and compare the price we’re paying on our current tariff with what the same energy would be on the Octopus Go “peak / off-peak” separation tariff. And the conclusion – semi-underwhelmingly, but equally reassuringly – was that at this time it would make roughly Bugger All difference. Around 20 quid more on the Go tariff.

Further detail is understanding how home-charging impacts our overall household expenditure compared to using the fast chargers in the park^[iv]And this is ONLY talking about the cost factor of park charging: to say nothing of the additional arseache of checking that a charger is available, and working, and you’re able to get your car … Continue reading like we have been (currently somewhere round 59p/kWh^[v]at this point can I register my own disgust at being the sort of person who publicly talks about price/kWh figures – this may well be the most boring post I’ve ever written, if you can … Continue reading / £25ish a time – vs the 33.86p on our home tariff), and then exploring what difference it would make to get an EV charger at home (~£800) versus the trickle cable plugged in to the domestic 13 amp socket^[vi]Oh christ, now he’s at it with amp capacity of sockets! Can this GET any boringer? as we currently have.

And THEN there’s the comparison to the new Intelligent Octopus tariff (which requires an EV charger), and burrowing through the FAQs to figure out what the ins/outs are.^[vii]I’ve got a sneaky suspicion that they’ll only charge the electricity going through the EV charger at the lower rate – but that’s a question to ask when I’ve recovered … Continue reading

On the bare face of it though our conclusion is that we’d probably need to be using, and therefore charging, our shiny Volvo^[viii]A totally separate conversation, but I do want to point out that this car is the first one I think I’ve ever actively enjoyed driving – I’ve enjoyed owning cars in the past, but … Continue reading a lot more than we currently are to materially benefit from tooling around with any of this. But it’s great to know the data’s there and we can see it in order to make these decisions.

I have a sneaky suspicion that the only way to make any of this really pay off over the longer term is to have a solar panel/battery setup – but the finer points of that are probably best left at this point to experts.

Any questions?

Update: 2023-02-08

I had a look at the rates on the Intelligent Octopus tariff as well and plugged them into the ol’ spreadsheet – the key points being that it’s identical to the Go tariff, except the off-peak time extends an hour in both directions (so 6h instead of 4h) and is 10p/kWh instead of 12.

The outcome is that instead of costing about 20 quid more, it only costs about 9 quid more. It WAS clear that the nights we charged the car we would’ve saved money, so the key factors remaining are how much we’re using the car, and then behavioural changes to get better offpeak use.

The dishwasher and washing machine both have delayed start functions, so that means that one cycle of each could be carried out on the cheaper rate. My feeling is that the remaining big draw items are the oven, the kettle, and the toaster – all of which necessarily have to be “on demand”. To get further benefits we’d need to move to using the slow cooker a lot more (and Liz has already nixed that because we’re still in possession of most of our teeth, so we can do that when we’re old), and buy a solar kettle (the obvious choice).

From further anecdote the reason one needs a specific charger to use this tariff is that Octopus can autonomously decide to charge your car outside the off-peak period at the off-peak rate, which means that all household use gets charged at the lower rate, so there’s an additional random factor. But you’d still need to stump up the £800 to have the charger put in.

As my friends & colleagues confirmed, you don’t really start making gains/benefit from this stuff unless you’re using a domestic battery and charging that at off-peak then using during the day, and/or harvesting your own juice using solar cells. So, additional cost, and the not insignificant fact that if more people start doing it then off-peak times will eventually cease to exist.

Yay.