This here says that two way meters are overpriced and unnecessary

Use two regular meters instead

OK… There are problems here. Part of the cost when buying a meter from the utility is that they have to install it and register it. Which costs. How much is an interesting question.

I don’t feel qualified to speak on having two regular meters, but surely this complicates wiring somewhat.

One of the two way meters they say you can buy for < 3k (the fronius) doesn’t seem to me to be much use to a utility. But I can’t even spel enjinear.

I guess it’s not just the bidirectionality but the TOU tariffs that add the complication. The meter needs to track these…

I asked about the viability of feeding in to the grid and @Phil.g00 said that you can do far better using that power yourself. That stuck and I’ve given up on that idea…
So I got CoCT to install their ‘split meter’.
It behaves just like my old Conlog pre paid meter but it has a device installed in their DB as well as the keypad unit inside. Why they did this must be for security but for the life of me I can’t work out how it functions… :space_invader:

TOU must require the meter to have comms with the billing system. Probably via cell networks. Not necessarily real time, but would have to send packets of data every few hours.

The billing system could take care of TOU billing as long as the meter tells them when the electricity was used.

Almost certainly is done that way. Otherwise tariffs or time slots change and they have to update every meter.

I should add that I’m not thinking of reselling. I’ve run the numbers several times, and it’s not even cost neutral for me.

Would this work? Can you just put them in series on the same circuit? You’d need two circuits - inbound and outbound - and the two would have to meet somewhere, so how I do stop my inbound meter (from the grid) picking up my outbound exported power.

Stopping now. I am not an engineer. My theorising here won’t even be theorising, just wild guesses.

In series but you wire the Outbound backwards. The have reverse feedback protection so the one will only move forwards and the other only in reverse (forwards but wired in reverse)

Subtract 1 from another to get Net Usage.

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Ah. Thanks.

One reason that comes to mind: Certification.

On a software level, it seems fairly straight forward to separate the direction of energy flow. I mean, Conlog and Landis can already disconnect and/or go into tamper mode if the energy goes in reverse, so clearly the hardware is capable of doing it. The whole thing probably needs to be certified though, and I suspect this is where the issue comes in. This is probably not cheap.

Yes. Because most of the time one will be in tamper mode. Which is why I’m struggling with the series setup. If you have either one in tamper mode, then effectively they both are. Even in parallel how do you keep what you’re exporting away from the input side of the meter that accepts power from the grid. (and without providing a path that some devious person could exploit).

I also read recently (wish I’d saved the link) that SANS or the Ministry have published a document describing an ideal setup for smart metering including resell, load limiting and TOU. Any municipality can elect to implement a subset of these features, but the meters must all be able to provide them such that a city can turn on a feature without having to send technicians all over the place (given the state of many municipalities, I can see this being filed under “nice ideas”). But there is already a list of seven meters that are approved and which all municipalities should now be using, and only those meters.

ISTR that Hexing was not on the list.

This must cost, sure, but it’s one off.

I wonder if we do the testing or if (as with appliances) the manufacturer just provides EU test results. (he said, wondering if he’d got that last bit wrong and would be corrected). One of the approved meters is from African Meter Systems, but I’d bet that’s just badge engineered.

You’d have to disable that feature. The meter would have to be configured to 1) not go into tamper mode on reverse flows (this is already possible with most of them), and 2) not bill reverse energy.

Indeed, if the meter is set up that way, you can wire both in reverse and pay nothing at all.

Now if we look at physical meters: Older disk meters often had a reverse lock-up feature, a bit like a ratchet. It can only turn in one direction, reverse feed is ignored. Two such meters wired back to back will actually work. But only in a post-paid setup.

Anyway, I am now wondering who this Eon de Koker guy is. According to the article he is CEO of TechSolutions, who seems to be in the RFID space (I actually worked with another company about a decade ago on a similar pallet tracking system… so quite interesting stuff for me as well). So while I don’t doubt his engineering credentials, I’m just curious if he is really on top of what it takes. Technically this stuff isn’t hard. There is some other reason we cannot just slap in any affordable meter, because I mean face it, ABB, Carlo Gavazzi, etc etc all make MID-rated meters that can do this, and they are cheap. The issue is probably not the meter. It is everything in the bigger system around that meter.

The mentioned Hexing meter is interesting though. Didn’t know they have such a meter…

I found the article. It is actually a “transversal contract” but underpinned by a specification.

Well the City has to be able to support the meters. Though if the strategy is rip it out and put a new one in then I suppose it’s not so bad.

Where I live there are at least four brands of meter in the field, and City Power are actively fitting two that I know of. A lot of the time they don’t have stock. Standardisation is good because the techs know what they’ll be dealing with. Some brands have acquired a reputation here because of Facebook posts (notably Hexing).

There is so much suspicion around meters and City Power and Eskom and, eventually, the government. Some folks wouldn’t do the TID upgrade because that was going to let “them” manipulate the price on the fly. Several of my near neighbours report increases in consumption that cannot be their fault because nothing they do has changed. But they don’t actually have any historic data, so they just say things like “it feels more expensive” (which it should because the tariff was increased in July - something that never seems to take folks by surprise).

I’m the type of guy you don’t want to sit next to at supper. I read both my meters every week, and log the readings in a spreadsheet, and I am very sure that the City are reading accurately. I don’t see anything like the increases these people are reporting, though it is certainly true that my bill has gone up as tariffs increased.

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“The technical specifications for the electricity smart meters state that service providers must handle the entire time-of-use tariff reading and billing process, as well as several kVA tariff and statistical meters.”

The above is the first of many requirements of the provider… I don’t this is a simple plug and play solution.
I don’t even think my local muni can import all this data and then Bill us yet…

Exactly. Being able to send all that data is all well and good, assuming you’re not out in the gramadoelas. I remember a trip I made to Fouriesburg. Vodacom just plain doesn’t work there (the nearest mast is actually in Lesotho, so you have to pay roaming rates) and MTN is present but sucks. Most of the locals were using ADSL at home.

So you first have to have the infrastructure to get the data to the municipality.

Then you have to have software to make sense of it all.

Johannesburg does actually have time of day billing, but you need a special meter (surprise) at your cost (surprise) and there are extra admin fees (by now you should not be surprised).

The problem with the utilities, frankly, is that you have elected councillors who may be very diligent and keen on serving their community but don’t necessarily know about about anything making decisions on IT systems.

SAP infamously screwed a very advantageous (for SAP) deal out of the City of Johannesburg. I’ve seen SAP operate. They start off with some outrageous figure just to find out exactly how lucky they are and how stupid you are. They don’t get offended with you if you cut the meeting short and tell them they need to sharpen their pencils because those figures look a bit odd. But COJ, convinced that nobody gets fired for buying SAP, voted on it very quickly.

But not all City entities have SAP. There is a famous breakdown in communications between Roads and Water. This is important because if Water come and dig up your street to fix a leak then they have to hand over to Roads who should come out and do the restoration of the road surface.

But there’s two different systems at play. I hope SAP didn’t tell the councillors that it is impossible to bridge this gap (because it isn’t so, and I know because I did that job and went on the SAP training), but that’s what the councillors and the Mayor and his lackeys all believe.

So what happens is that all the details of holes dug by Water get captured into a spreadsheet, which gets emailed to Roads, who (assuming it hits the right mailbox) have to print the spreadsheet out and capture everything manually. Which is slow and error prone.

Clearly the City doesn’t believe in getting some actual IT experts in. Not to have a vote (they can’t), but just to explain the facts of life. It’s all left up to people who are there because where you live most folks like that party. I don’t want to disrespect these people, I believe they are hardworking and (mostly) honest, but they weren’t elected for their technical expertise.

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