Octopus Cosy & Octopus EV + bidirectional smart tariff, together. What, eh?

Electricity, Tariffs, Monitoring & Providers

Last Post by Old_Scientist 16 hours ago

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AllyFish

(@allyfish)

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Joined: 3 years ago

Posts: 493

Topic starter 05/08/2025 10:57 am

Well, Mrs F and I have got ourselves on Greg's pre-order waiting list for the BYD Dolphin + Zaptec Pro Bi-directional Charger & smart tariff.

https://octopusev.com/resources/news/octopus-and-byd-make-waves-with-all-inclusive-car-and-v2g-charging-bundle.

£300 a month. Seems a good deal. The Mrs can purchase through her employer's salary sacrifice scheme as well.

My wife and I both WFH and the vast majority of our car use is shorter local journeys from home. Her 62 plate Suzuki Swift car is getting old and a little pricier each year to keep roadworthy. So a shared EV as our next daily makes sense, with my t-rusty, old & smelly 63 plate Nissan N-Trail SUV reserved for long hauls, family hols towing the trailer tent or taking the E-bikes out on the bike rack, & tip trips.

The Dolphin EV will mostly sit there on the drive, plugged into the 'grid-of-things' which is exactly what Octopus want, so they can charge and discharge it remotely with vehicle to grid [V2G] bi-directionality. Hopefully leaving us enough ziggies in it to get out and about! The value proposition to Octopus is using our leasehold car as a BESS, so they can make money out of it. The value proposition to us is a shiny new EV with a very attractive and affordable monthly lease via salary sacrifice and free ziggies [i.e.: inclusive in the lease cost] to use it.

But wait, we already have solar PV + BESS + Cosy + ASHP heated all-electric house. Surely the two can't be compatible? There's only one DNO connection to the house, and only one SMES2 smart meter in the box outside. How can they know what's being charged & when? The car, our BESS? Well, they say they can. Maybe the Zaptec Pro charger has some clever electronics inside, or even some internal energy metering and monitoring?

Our BESS is a modest 13kW, which works for us charged 3x a day on Cosy, we don't have enough BESS capacity to leverage a really low overnight EV tariff that would last through the following day, nor the option of increasing it. We would have to disable the export on the solar PV. We get that, and as we don't export much anyway, We're OK with that.

So how can we keep Cosy tariff, which saves us a fortune in winter, shifting almost 90% of our import to low rate, and also have a V2G third party managed BYD Dolphin BESS sat on the drive, with the electric to charge it included in the leasehold? It's a question I've put variously to Octopus Energy and Octopus EV. I await a definitive answer as they bounce this issue, and us, between themselves. It all sounds too good to be true, and the cynic in me, etc....

This topic was modified 17 hours ago 3 times by AllyFish

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Old_Scientist

(@old_scientist)

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Joined: 1 year ago

Posts: 193

05/08/2025 12:14 pm

The current FAQ says it's not compatible with existing solar or battery exporting:

https://octopusev.com/power-pack-bundle/terms

At the moment this product will only be available for people who do not already export to the grid (e.g. from solar or battery)

but you've already identified that. How will you prevent any excess solar from being exported?

I remember reading about this at the time it was announced. Some members on another forum compared the deal to other comparable leasing deals for the same vehicle, which were coming in at around £280/month, so the £20 saving can buy you ~160kWh of electricity per month at Cosy cheap rates.

How much solar export are you giving up? Add that into the mix (at 15p SEG), and where does that leave you in cost terms?

I love the idea of V2G and I love the fact Octopus are pioneering the technology, but this particular package just looks far to limiting for someone like yourself with existing solar and BESS.

Following your journey with interest 😀

Samsung 12kW gen6 ASHP with 50L volumiser and all new large radiators. 7.2kWp solar (south facing), Tesla PW3 (13.5kW)
Solar generation completely offsets ASHP usage annually. We no longer burn ~1600L of kerosene annually.

👍

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