Based on this discussion it's pretty convincing that this can't work for the nation if run as a business, which of course doesn't mean that it's technically silly!

Is it remotely possible that there are things that collectively we need and could have but which don't make business sense, and thus need to be run on a different basis. 

Light bulb moment - that's why we have government!  Who would have thought that?

Posted by: @johnr

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On the wider issue of getting surplus generation in Scotland to the demand centres in England, I feel that there's been insufficient fending off of the NIMBYs in favour of the national interest. Undersea cables are a much more expensive (thus tying up more available capital) and vulnerable way to move power than overground powerlines which I find tend to become part of the scenery once the metal is no longer shiny.

You're slightly too late to raise this issue now.

The proposed East Coast Marine Links were open for consultation in 2021-22.

HVDC cable 2 from Peterhead to Drax (Yorkshire) was approved by Ofgem on 15th August'24.
It's one of three DC Marine cables for the East Coast which must be operational by 2030 in order to hit the target for decarbonisation of the grid.

You can find out a lot more on the HVDC Marine cables from SSEN, who intend using the technology between the mainland and Scottish islands.

As for cost, it will in fact be cheaper than erecting additional Transmission Towers (pylons) through the Scottish lowlands.
Using HVDC (800kV and above) not only reduces losses, but simultaneously overcomes the problem of the Scottish Transmission Grid running at 275kV, rather than 400kV.

I don't know enough about how commercial BESS sites make their finances work. I've spoken to NESO, who tell me that they have no direct control over any generation or storage sites. They have a messaging system which allows them to call for power, or pay to have a generator on standby. It's up to the Generator to respond to that message, within the terms of their contract.

There are more than 1500 commercial BESS sites in GB now.
The vast majority will be operated remotely. So their communications system is an extremely important part of the design.
Any possibility of BESS being subjected to a hostile cyber-attack must be regarded seriously.

Posted by: @ianmk13

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Won't riding on the back of a residential sub-station adversely affect the availability of import/export capacity for the local residents?

Yes, of course.

A BESS connected at the LV level (440v) is no different to having a new 3ph supply to a commercial building.

But the BESS controls are operated with limited vision.
They will be able to see the voltage of the supply from the (adjacent) substation, but there are no sensors to provide feedback from the far ends of the other Feeds from the same transformer.
Nor is there monitoring on the incoming supply to that transformer at the higher voltage level.

That's somewhat precarious.

If operating the BESS results in the 'far-end' voltages falling outside the accepted range of 216v - 253v, then any inverters or EV-chargers at those homes will disconnect themselves from the grid.
That's a requirement of their G98 certification.

See the story above!

Posted by: @ianmk13

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What about those who have not yet been able to afford their EV but will soon be compelled to? Will there be any capacity left in the sub-station for them?

A DNO may not reserve capacity for such a scenario.

If the point of connection currently has capacity available, then the BESS Applicant will be sent an Offer to Connect.

As we progress further towards Net Zero there will undoubtedly be sites where the substation will be running close to (or beyond) its rated capacity.
The DNO must replace/upgrade transformers and Feed Cables to satisfy that additional demand.
The cost of that comes from increased bills for consumers (in that DNO Licence Region).

That's a financial reason why Battery Storage is best installed in the home, rather than connected directly to the grid.

It's also disingenuous for a commercial BESS applicant to suggest that they're helping the national migration towards renewable generation if they're recharging during a cheap-rate overnight time-slot.

The after-midnight period is 'cheap' because it allows CCGT generation plants to remain in combined cycle at 50% efficiency.
If their output drops too low they enter open-cycle mode at 35-40% efficient.

Posted by: @johnr

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As someone who is considering buying an EV within a few years, I would much prefer to invest in one which supports V2H and V2G given that the vehicle is likely to spend much of its time parked outside my house. I've always understood that most of the wear on the lithium chemistry is at the ends of the charge range and charging/discharging in the middle of the range doesn't cause much wear. Forward scheduling of likely vehicle usage could enable software to manage both the charging and some export while ensuring there's plenty of juice in the battery ready for the next journey.

"within a few years" is a pretty long timeframe within the world of EV development.

The Automated Vehicles Act was passed in May'24. It provides the regulatory basis for UK to leap over Level-3 of autonomous transport, and to allow Level-4 vehicles on the highway by 2026.
Level 4 autonomous electric vehicles (AEVs) are fully self-driving within a geo-fenced area and do not require a human driver to be ready to intervene.

That opens up a wide range of possibilities for hail-on-demand public transport.

Some households may decide to no longer own a vehicle themselves.
Others will own a small EV personally, and hail a larger van if they have goods to collect.

The requirement for home-charging will drop,
as will the need for town-centres to keep parking spaces for static vehicles.
The desire for V2G will become diminished.

I've spoken with National Grid Electricity Transmission (NGET) about the future electricity demand from EVs.
Even if all cars were to be electric, it would only add 10% additional demand to the grid.

So there is sufficient grid capacity, although obviously not simultaneously!
Locational/nodal pricing and time-slicing are crucial to the future of personalised transport.

I'm fully aware that I've just opened a load more questions by responding to your original point like this!

Please feel free to comment further.

The Brave New World of local micro electrical grid management... 

not to mention globalised infrastructure. The President of China's ally North Korea having a fun day at the office...

Be careful what you wish for.