Anyway, I suspect it depends on the space in the cupboard. Our meter cupboard is a standard size (I suspect an off-the-shelf design) but restricted clearance (the door only just opens all the way) and meter installation seemed straightforward. Power was off for maybe 30 minutes. The new meter and its communications gubbins takes up more of the cupboard than the old one did.

While installation was straightforward, it took months (3 months I think) to finish getting billed for the old meter and switch the account fully to the new one, get it recognised as smart, get it recognised as reliably sending half-hour data daily, and so get access to smart meter tariffs and features.

It was straight forward for me. External metre box, my then supplier OVO installed the smart meter. I was pleasantly surprised that, even though it was an older smart meter, it has import and export monitoring and is fully compatible with Octopus smart tariffs. Cosy Octopus has saved me 25% on my electricity bill the last month, by switching the vast majority of my grid consumption to their lower rate tariff. That's with a fairly modest 6.5kWh solar PV battery charging twice a day. Octopus had me fully transferred, first onto a standard price cap tariff, then Cosy within 2 weeks. Cracking service from them. I had to chase OVO for the £500 credit refund they owed me. No surprise there....

Is there just one type and make of smart meter or do different providers/installers use different brands/sizes?

AFAIK, SMETS2 2nd generation smart meters are able to share data between suppliers. Each energy supply company will partner with a 3rd party smart meter installation company, but you can chop and change provider as long as the meter installed is SMETS2. 

Posted by: @editor

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Is there just one type and make of smart meter or do different providers/installers use different brands/sizes?

As I understand it, there are two types (SMETS1 no longer installed, SMETS2 now) but many makes and models and there seems little pattern to what you get where and from which supplier. They all connect to a few specialist smart meter network providers (Secure and DCC are the two I've seen most) and from there to all energy retailers and third-party smart meter device makers.

Posted by: @editor

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given that the water metre we just had very recently installed was a real bodge job and not very sympathetically done.  

@editor

Picking up on this do you think your water leak issue might be connected to the meter install

@editor there different brands. but any new one will be SMETS2.

I've had 2. first one did the metering ok, but got confused when the powerwall was fitted later. When that was taking all the house load, so when import was truly zero, it would still read 100W import, which I was getting billed for. it added up. octopus covered it to be fair.

The second one , a different brand, was able to cope with zero really being zero.

The electrical path goes DNO fuse -> meter -> tails to your Consumer unit (or battery system if you have one). provided those physical tails are easy for them to get at, its a relatively uncomplicated thing. if they are hidden behind cupboards then you may well have some disruption.

they will be assuming its in an easy access meter cupboard.

depending on where you are in the country, local geography, then comms between the meter and the DCC network can be an issue. I've not had any but this is commonly discussed in other forums.

There's good overview of Smart Meters over on the Smart Me website,
and another explanation about SMETS2 meters on the OVO Forum, written by someone called Transparent.
I can personally vouch for their depth of knowledge on the subject 😉 

It was seamless for the electricity (E.On).  Smart meter+comms is larger than the old meter.  Switchover was prompt.  IHD worked fine.

The gas meter was also seamless on installation (British Gas) and it piggybacks on the electricity meter comms.  But the guy really didn't want to wait around to check everything worked fine and dashed off.  Meter readings are getting done fine but nothing is displayed on IHD.  I got another IHD off Hildebrand and am using that now.  That also has the advantage of having my smart meter data archived by them and available via Bright app.

Our smart meter install with OVO went fine.  It's a lot bigger than the old meter we had before, but there was space.  I find it more awkward to read a value off it than the old one, and it has lots of blinking lights.  Sure it's clever with it's 1/2 hour readings, and the little display thing.  I do still look at it, nobody else ever did.  It takes batteries, but lasts literally 5 minutes on them, so is left plugged in.  In contrast I have an "eco-eye" PV digital display which lasts years on a pair of AA batts! 

Moving it over to Octopus 3 years later to get on the go tariff was slowww.  It was smets1, but Octopus supported it.  I emailed loads of times, and kept going to different people, everyone asking for photo's of the install etc.  Octopus could see the gas meter, which routes via the elec one, but not the elec one!  After 3 months of this I tweeted @Octopus - that got a response straight away, and it got fixed in a few days!  I still don't know what it was, some techie thing totally at their end. 

The only reason I'd advise getting a smart meter is if you want a smart tariff 😍.  The reason not to get one is if there is any danger of failing to pay a bill - you'd get put on a payg tariff, which leaves you vulnerable to the industry euphemism of "self disconnection".

I think Smart Meters are better understood with graphics.

This block diagram shows the main elements comprising the National Smart Meter Network

Four 'devices' are installed within your home if you have gas.

Note that the Communications Hub is physically bolted on top of the electricity meter, from which it draws about 6-watts (max) to operate.

A Smart Meter has a number of functions (ignoring those which are purely related to its internal workings and security)

1. Obtain cumulative usage readings every half-hour and store those for the previous 13-months (both for import and export)
2. Hold a copy of your present tariff data, and thereby support operation using a Time-of-Use tariff
3. Handle pre-payment meter credits, notifications and alerts
4. Operate a Block Tariff, if implemented by the Energy Supplier
5. Operate Load Limiting when commanded to do so
6. Hold and operate a Non-Disablement Calendar
7. Provide Auxilliary Load Control Switching (ALCS) of devices in the home

At present (Feb'23) the UK Energy Suppliers have only implemented the first three functions, which are those of interest to themselves.

The remaining four features are of greater benefit to the end-users.
They provide functionality which can

• reduce bills for households with lower usage
• counter Climate Change and the Energy Crisis
• protect households on the Priority Services Register
• reduce losses on the Distribution Grid

The Energy Regulator shows little interest in requiring these useful features to be implemented.