Smart Meter Installed - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: September 03, 2024, 01:40:36 am
content: My net energy meters have been replaced with a new fangled Smart Energy Meter as we call them in Australia.This gives the option of potential time of day usage using other energy providers that offer low cost off-peak energy rates for battery or EV charging.I presume I can connect the IR port on the front for capturing the data?https://www.youtube.com/shorts/OGYexV34vCU

author: darkspr1te
author_rank: Frequent Contributor
timestamp: September 03, 2024, 07:34:49 am
content: Search you fav tech store for Win7/8/10/11 USB to IR Infrared Optical Adapter for Energy Meter IEC1107 DLMS kWh Meterif you are wanting wireless then there is a Tuya based device for that but it requires the smartlife/tuya home app and pulling data to other sources is hard.if you have a HomeAssitant setup then usehttps://community.home-assistant.io/t/electricity-smart-meter-optical-ir-port/327517/7darkspr1te

author: nali
author_rank: Frequent Contributor
timestamp: September 03, 2024, 09:11:39 am
content: That IR port is more or less the smartmeter version of a UART0 debug... engineers can upgrade the firmware and do a bit of poking around through there. Don't expect anything tasty though, they're properly locked down.

author: Gyro
author_rank: Super Contributor
timestamp: September 03, 2024, 09:17:23 am
content: Do they not provide you with home displays (IHD) in Australia? They do in the UK, which give you individual and combines energy information if you have a smart gas meter too.They're by no means perfect, but they can provide a fair amount of statistics.Eg.They communicate over Zigbee.

author: woofy
author_rank: Frequent Contributor
timestamp: September 03, 2024, 09:59:29 am
content: The home display that came with my smart meter was pretty minimal and the meter doesn't monitor everything I wanted anyway.I built an ESP based energy monitor that can take up to 8 CT clamp inputs. This sends an MQTT message to Home Assistant every 10 seconds, measuring current, power direction and mains voltage.I'm currently monitoring 4 items, Grid, Solar, Battery and EV charging. The smart meter would only give me grid info so I didn't bother with it, though I can see what its up to on the monthly reports from Octopus.Unless grid info is all you require, an energy monitor may be a better option.

author: Someone
author_rank: Super Contributor
timestamp: September 03, 2024, 10:41:14 pm
content: Quote from: Gyro on September 03, 2024, 09:17:23 amNot sure anyone had them provided for free, but displays were/are available for the meters with zigbee (which is not all of them). Uptake is minimal/non-existent, yet people with solar love their phone apps for some reason.

author: EEVblog
author_rank: Unknown
timestamp: September 04, 2024, 12:47:47 am
content: Quote from: Gyro on September 03, 2024, 09:17:23 amNope, not a thing here AFAIK

author: Someone
author_rank: Super Contributor
timestamp: September 04, 2024, 03:41:42 am
content: Quote from: EEVblog on September 04, 2024, 12:47:47 amWell known enough for the government to talk about them:https://www.yourhome.gov.au/energy/connected-homeand it was supposed to be one of the main benefits of smart meters:https://www.awa.asn.au/resources/latest-news/community/engagement/smart-meter-technology

author: Jeroen3
author_rank: Super Contributor
timestamp: September 04, 2024, 06:28:54 am
content: The IR port may blast some data every x seconds. You can get readers for those.Yours has IEC 62056-21The frame may look like thisCode:/ISk5\2MT382-10001-3:0.2.8(50)0-0:1.0.0(101209113020W)0-0:96.1.1(4B384547303034303436333935353037)1-0:1.8.1(123456.789*kWh)1-0:1.8.2(123456.789*kWh)1-0:2.8.1(123456.789*kWh)1-0:2.8.2(123456.789*kWh)0-0:96.14.0(0002)1-0:1.7.0(01.193*kW)1-0:2.7.0(00.000*kW)0-0:96.7.21(00004)0-0:96.7.9(00002)1-0:99.97.0(2)(0-0:96.7.19)(101208152415W)(0000000240*s)(101208151004W)(0000000301*s)1-0:32.32.0(00002)1-0:52.32.0(00001)1-0:72.32.0(00000)1-0:32.36.0(00000)1-0:52.36.0(00003)1-0:72.36.0(00000)0-0:96.13.0(303132333435363738393A3B3C3D3E3F303132333435363738393A3B3C3D3E3F303132333435363738393A3B3C3D3E3F303132333435363738393A3B3C3D3E3F303132333435363738393A3B3C3D3E3F)1-0:32.7.0(220.1*V)1-0:52.7.0(220.2*V)1-0:72.7.0(220.3*V)1-0:31.7.0(001*A)1-0:51.7.0(002*A)1-0:71.7.0(003*A)1-0:21.7.0(01.111*kW)1-0:41.7.0(02.222*kW)1-0:61.7.0(03.333*kW)1-0:22.7.0(04.444*kW)1-0:42.7.0(05.555*kW)1-0:62.7.0(06.666*kW)0-1:24.1.0(003)0-1:96.1.0(3232323241424344313233343536373839)0-1:24.2.1(101209112500W)(12785.123*m3)!EF2F(such frames also contain unique identifiers, careful)Basically contains all counters and most recent instantaneous measurement. Obviously above example is a three phase meter, probably a dutch one.OVer here it's called DSMR (dutch smart meter requirements) or the P1 port (customer facing port) often also available as rj11 on meters here.The field codes are called OBIS Codes, and should be universal.It was made available so we can check the meters functionality and get immediate insight into consumption. Also to interface appliances that require tariff switching, since the PLC tariff switch signal was turned off. Many EV chargers use it for to dynamically limit their current to prevent overloading the main fuses.Try it! Maybe yours has those features as well.Or your government is like, "ah who cares, we don't need that" judging by the deplorable state of distribution panel you have over there

author: IanJ
author_rank: Unknown
timestamp: September 04, 2024, 09:23:56 am
content: I got a Smart Meter installed a couple years ago but then unbeknownst to me it started failing to Tx back to my energy company (Scottish Power).Then, in the meantime I switched providers (Octopus) when I got my battery installed and before I could switch to the battery efficient Octopus Tariff they needed to confirm my Smart Meter was working as was routine.They told me it wasn't and so began 6 months of back and forth, engineers visits etc, and eventually they switched it out for a new one........which also didn't work!I was told maybe it could be due to location of the meter and maybe it needed moved.One last ditch effort I called them and happened this time to get a tech savvy dude.......and I went through everything with him and lo & behold it turned out there were 2 meters associated on my account......and they were trying to read the 'other' one. So, as soon as it was deleted off my account and they tried reading the new one.....it worked.A lot of folks 'hate' smart meters but really......the benefits are awesome.Here's my install below. House stuff, Solar, Battery, and my own modbus equipped meter which I got installed (green illuminating LCD) as I hate using loose CT's.Ian.

author: nali
author_rank: Frequent Contributor
timestamp: September 04, 2024, 10:29:42 am
content: @IanJwhat was the issue with the meter? I'm curious as I'm about to go the same route but having issues with my current electricity supplier (British Gas). Their service / support is absolutely dire, the worst I've encountered by a country mile.This house had an old SMETS1 meter when we moved a couple of years ago, but to compound that it was installed by another providor so they have no means to access it to read or upgrade it. After 6 months of bullshit I forced them via the Ombudsman to swap it which they've now done. Trouble is they've managed to mis-configure the system so the in-house display now thinks it should be showing a gas reading. It is reporting electricity useage though as I can see it via my online account.Lies / excuses/deflections are all boilerplate responses, so far have included:Turn it off & on, then leave it for 1 weekThey take 1 month to fully synchronize via the networkIt's too far from the meter (it's about 2m away)Maybe it's picking up readings from next door (we live in a village with no gas supply in the area)I've escalated to our back office specialists<1 month silence>We'll send you a new displayAs soon as they "action" something like escalate to another team, they close the case and email thread. Fucking muppets.

author: coppice
author_rank: Super Contributor
timestamp: September 04, 2024, 10:55:12 am
content: Quote from: IanJ on September 04, 2024, 09:23:56 amI think you just described why so many people hate them. Your experience is not uncommon. You'd think that after the first couple of weeks of the plebs getting nowhere fixing problems, they'd get someone competent involved. It seems it typically takes more like the 6 months you experienced. Unless you have local generation, or a specific time based tariff demand profile, like heavy EV charging overnight, its hard to see a material benefit they bring to most domestic consumers. I say this as someone who spent a lot of my time over a number of years involved in the metering business, implementing various features that were being asked for, and looking into how they are used. Why do you think the utilities are OK with a meter not reporting regularly for months? Could it be that even the utility couldn't care if these things work or not?

author: IanJ
author_rank: Unknown
timestamp: September 04, 2024, 11:16:08 am
content: Quote from: nali on September 04, 2024, 10:29:42 amSo, under Scottish Power I believe the original meter went faulty....hence comms was failing.Then when Octopus installed the new meter after I switched to them, and it wouldn't work, it finally dawned on me that maybe the Octopus operators were trying to connect to the original meter (long gone) because they were both appearing as listed in my Octopus login.I had mentioned this several times before but it FINALLY took a really good non-foreign tech savvy Octopus operator to listen to what I was saying 'again' and go away and look into it. He phoned me back within 10mins with the words"it's done, I can see your meter data now, all good".PS. I never mentioned that I had also tried emailing the CEO of Octopus (google search for his email) and I got a personal reply saying they would get it sorted......and they tried, but a month later everything slowed down again. Only my persistance got it fixed in the end.Ian.

author: EEVblog
author_rank: Unknown
timestamp: September 04, 2024, 12:36:19 pm
content: Quote from: Someone on September 04, 2024, 03:41:42 amMaybe a state choice thing, I have never been offered such an option.

author: Gyro
author_rank: Super Contributor
timestamp: September 04, 2024, 12:46:11 pm
content: IHDs do make you look at your energy consumption. You tend to get quite paranoid, hunting for your night time 'base load', number of appliances left in standby, lights left on etc.... This phase typically lasts 2-3 weeks before acceptance and resignation set in.

author: EEVblog
author_rank: Unknown
timestamp: September 04, 2024, 12:48:44 pm
content: Quote from: Gyro on September 04, 2024, 12:46:11 pmI already have this with Solar Analytics. But it would be nice to have a dedicated low powered LCD desktop display.

author: IanJ
author_rank: Unknown
timestamp: September 04, 2024, 02:17:05 pm
content: Quote from: EEVblog on September 04, 2024, 12:48:44 pmNote sure if Dave's EDMI meter has the HAN network protocol built in for use with an IHD since not all of them do.......might be worth looking into it and if it does then just buy an IHD and pair it up.Ian.

author: coppice
author_rank: Super Contributor
timestamp: September 04, 2024, 02:44:35 pm
content: Quote from: Gyro on September 04, 2024, 12:46:11 pmI think existing IHDs are pretty useless for 99% of people. However, the complete cluelessness of the average person about the relative consumption of different appliances makes me have some hope that a better form of showing the speed at which the bill is going up could make some difference to their behaviour. My mother in law burnt her hand on our wok that was on full power (maybe 5kW of gas) a few years ago, because she was trying to save energy by not turning on the 20W of LED lighting on the extractor hood. I thought it weird that she regularly cooked in dim lighting, but I had no idea why until that moment. Even places where there should be some basic technical knowledge, like mythbusters, have had some bizarre things. Like investigating the meme that fluorescent lights consume almost all their energy as they start up. That was never a meme. The actual meme is accurate. Fluorescent lamps suffer most of their wear and tear during warmup. Few people seemed to twig that they'd got the meme wrong.

author: Someone
author_rank: Super Contributor
timestamp: September 04, 2024, 11:36:29 pm
content: Quote from: EEVblog on September 04, 2024, 12:36:19 pmYou said Australia, a false generalisation. Perhaps look outside your backyard before trying to make big claims? How hard would it have been to simply say "I've never seen one" or "not something I had the option of" ?

author: EEVblog
author_rank: Unknown
timestamp: September 05, 2024, 12:49:34 pm
content: Quote from: Someone on September 04, 2024, 11:36:29 pm

author: EEVblog
author_rank: Unknown
timestamp: September 05, 2024, 12:52:13 pm
content: Display has now changed in the retailer portal.I just get a daily import/export figure. And it just pegged some constant value for all previous days before the install.

author: tszaboo
author_rank: Super Contributor
timestamp: September 05, 2024, 01:34:05 pm
content: We had a lot of EDMI meters in Belgium. MK7B as I recall was the standard. That is quite a bit different layout than this.By the looks of it, your meter has 4 outputs. "TB2" "TB3" "TB4" and infrared.TB3 is permanently connected to a logger/modem. It's RS485, so technically you can tap into that. I don't know if they would consider that tampering.On the other hand TB4 is supposed to be the RS485 as well, so I would stick a converter or a scope on that and see if there is any communication going on there. For the Dutch market, they report it on the serial port every 10 seconds.

author: Someone
author_rank: Super Contributor
timestamp: September 05, 2024, 10:00:41 pm
content: Quote from: EEVblog on September 05, 2024, 12:49:34 pmOr perhaps you could not walk into discussions and drop narrow minded nonsense that is factually incorrect? Only takes a tiny bit of explanation/framing from you, and then you'd not be wrong.

author: EEVblog
author_rank: Unknown
timestamp: September 06, 2024, 01:39:41 am
content: Quote from: tszaboo on September 05, 2024, 01:34:05 pmThere is an anti-tamper tag on the front preventing removal of the panel to access this stuff.

author: EEVblog
author_rank: Unknown
timestamp: September 06, 2024, 01:44:56 am
content: Quote from: Someone on September 05, 2024, 10:00:41 pmWhat is your problem?I said "Nope, not a thing here AFAIK". I literally included "As Far As I Know" which indicates that I didn't know for sure, just that I had never heard of it and that obviously invites other people to correct me.Do you think I care that I'm wrong? Seriously?

author: EEVblog
author_rank: Unknown
timestamp: September 06, 2024, 02:02:02 am
content: FYI, my current provider AGL does not offer any in-home display or real time monitoring option for the new smart meter.I have Solar Analytics of course, but they don't offer any sort of in-home desktop display, it has to be done on the phone app.

author: Someone
author_rank: Super Contributor
timestamp: September 06, 2024, 06:46:11 am
content: Quote from: EEVblog on September 06, 2024, 01:44:56 amHave a look at the context. I put forward a considered opinion and the very next post is you disagreeing with it. Which you'll now agree was incorrect/"wrong". You can not care but it'll get called out as disruptive. Now this thread is mostly you beating your chest.... so what is your problem? Not wanting people to point out incorrect information?You're basically ignoring the (even referenced) content and just saying whatever you feel. Which I've pointed out is narrow minded and not helping. So why is your opinion so important.. when it's wrong?

author: EEVblog
author_rank: Unknown
timestamp: September 06, 2024, 09:59:53 am
content: Quote from: Someone on September 06, 2024, 06:46:11 amYou are delusional.I responded to your correction with "Maybe a state choice thing, I have never been offered such an option." No malice in that, no attack, just saying what my experience was here in NSW.Then YOU attacked ME with the response of "You said Australia, a false generalisation. Perhaps look outside your backyard before trying to make big claims?How hard would it have been to simply say "I've never seen one" or "not something I had the option of" ?"And you did that when I literally did exactly as you requested (bold above) and replied essentially with your suggested "I've never seen one" (I said: "I have never been offered such an option")Bugger off. I won't make the mistake of replying to you again.

author: Jeroen3
author_rank: Super Contributor
timestamp: September 06, 2024, 11:04:59 am
content: Quote from: EEVblog on September 06, 2024, 01:39:41 amAre they numbered?

author: EEVblog
author_rank: Unknown
timestamp: September 06, 2024, 12:05:45 pm
content: Quote from: Jeroen3 on September 06, 2024, 11:04:59 amI'll checkI presume you can just buy them at Tradelink or something...

author: coppice
author_rank: Super Contributor
timestamp: September 06, 2024, 01:43:51 pm
content: Quote from: EEVblog on September 06, 2024, 12:05:45 pmIts usually easy to get bare tags. Marking them is how they get some security. Some make the marking hard to fake. Some make it easy.

author: Njk
author_rank: Frequent Contributor
timestamp: September 07, 2024, 06:12:29 pm
content: Me too. Shit has happened recently. The utility did replace my meter with a "smart" one. In a bandit's way. I was out when they came and left in the mailbox the official paper which states that my old meter is found defective because the readings are not changing (no wonder since no current consumption was taking place at that time).Later, I was able to negotiate with the metering company my access to the metering server over the internet. But what I can see there is only the consumption data, like load profiles, and the meter's event log, nothing else. I can't see the meter settings. It's a pity because the meter has a load switch that can disconnect the power if the current has reached certain threshold, which can be changed by them remotely at any time (demand response policy). Now I've to buy or build the IR adapter to read all the settings in that way, with the hope they didn't change the default read password by the laziness.

author: EEVblog
author_rank: Unknown
timestamp: September 08, 2024, 11:18:22 pm
content: I just noticed that one day last went they marked as "High feed-in".I presume they think that's bad?And now it hasn't updated over the weeekend.And I haven't had a single day yet where I haven't used at least some grid energy, which seems odd. But maybe this was some peak that couldn't be supplied by the solar at the time or the battery, which is possible, but I'll keep an eye on that.

author: tszaboo
author_rank: Super Contributor
timestamp: September 09, 2024, 07:50:34 am
content: Quote from: EEVblog on September 08, 2024, 11:18:22 pmDo you have a single phase system of three phase?I don't exactly know how this will work, but I have a feeling that houses with 3 phase (like me) will get a nasty surprise, when it will be impossible to balance out the generation with the consumption, and get billed for both when the oven is on a different phase as the panels.

author: Siwastaja
author_rank: Super Contributor
timestamp: September 09, 2024, 08:02:37 am
content: Quote from: tszaboo on September 09, 2024, 07:50:34 amThis was the case years ago here on some grid companies. Others calculated net sum over the three phases, because really, that's the decent thing to do. This summing was made mandatory by law and the dickhead companies had to follow.I would be surprised if you didn't have such summing requirement in place. Indeed absence of phase summing makes self-usage much more difficult. I tried to hand-optimize this in 2021 dividing loads evenly into the phases.Another orthogonal question is the time period of summing. 20 millisecons? 15 minutes? 1 hour? This makes a big difference on the bill. For example if billing net sum period is 1 hour, oven thermostat has shorter cycle and you can self-use your PV in an oven pretty well. E.g. if PV produces 2kW and oven consumes 4kW at 50% duty cycle and 15-minute period, you have perfect self use (zero net sum) on a 60-minute interval, but on a 15-minute interval you, in worst case if they sync in worst possible way, alternatively sell 2kW and buy 2kW for each 15-minute period.Instead of speculating, do a few Google searches to see how it is in your country / your grid service.

author: EEVblog
author_rank: Unknown
timestamp: September 09, 2024, 08:12:53 am
content: Quote from: tszaboo on September 09, 2024, 07:50:34 amSingle

author: tszaboo
author_rank: Super Contributor
timestamp: September 09, 2024, 08:28:34 am
content: Quote from: EEVblog on September 09, 2024, 08:12:53 amMaybe then it's the variability of the load and generation. I was playing around with logging the data from the smart meter and the inverter.The meter reports data every 10 seconds through a consumer accessible port called P1. On my inverter the Ethernet-modbus is opened, and I request the generation every minute. So my self consumption is technically can be calculated by summing the two, right?Not so much. There is a delay in the system. An heater in an oven can turn on and off every few seconds. Solar insolation also changes every few seconds.The end results were spikes of power consumption and generation that sounds like a nightmare to balance out, even with a battery.

author: Siwastaja
author_rank: Super Contributor
timestamp: September 09, 2024, 08:37:19 am
content: Quote from: tszaboo on September 09, 2024, 08:28:34 amYou should be reading out energy counters and take differences to find average power within any arbitrary interval. If you read power registers, you really need to do the sampling pretty frequently to avoid the aliasing problems you describe.These meters often have separate registers for buy/sell energy. To get same numbers as in your bill, you need to know the time period over which you can just sum these two numbers. Since the rules in netting vary country-by-country or even within country, you need to Google or ask around to learn how the billing works for you.

author: tszaboo
author_rank: Super Contributor
timestamp: September 09, 2024, 08:40:46 am
content: Quote from: Siwastaja on September 09, 2024, 08:37:19 amYou are still on my ignore list.

author: Siwastaja
author_rank: Super Contributor
timestamp: September 09, 2024, 08:57:38 am
content: Quote from: tszaboo on September 09, 2024, 08:40:46 amWTF, is "energy counter" some swear word in Dutch? Anyway, I meant that through the P1/H1 ("HAN port") interfaces you can get power values, but you also get energy counters, this means power value accumulated internally in the meter at very high sampling speed, so you can read them out less frequently and take a difference for average power for any arbitrary period you wish, without aliasing issues. If you are not interested in a solution to your problem, why do you post about your problem on the forum then?

author: tszaboo
author_rank: Super Contributor
timestamp: September 09, 2024, 09:09:03 am
content: NOTE: This message has been deleted by the forum moderator Simon for being against the forum rules and/or at the discretion of the moderator as being in the best interests of the forum community and the nature of the thread.If you believe this to be in error, please contact the moderator involved.An optional additional explanation is:

author: Andy Chee
author_rank: Super Contributor
timestamp: September 09, 2024, 09:32:10 am
content: Quote from: tszaboo on September 09, 2024, 07:50:34 amEven with three phase, one would assume that your power bill has a single total kWh, not kWh per phase.When single phase solar energy export is factored into the equation, it merely subtracts from the total kWh, not the kWh per phase.

author: tszaboo
author_rank: Super Contributor
timestamp: September 09, 2024, 10:05:03 am
content: Quote from: Andy Chee on September 09, 2024, 09:32:10 amWhen I read out the meter reading, it registers currents separately on different phases.It will read import and export at the same time. This is the message format that the meter sends every 10 seconds:Code:OBIS CODEMEANING0-0:96.1.4ID0-0:96.1.1Serial number of electricity meter (in ASCII hex)0-0:1.0.0Timestamp of the telegram1-0:1.8.1Rate 1 (day) – total consumption1-0:1.8.2Rate 2 (night) – total consumption1-0:2.8.1Rate 1 (day) – total production1-0:2.8.2Rate 2 (night) – total production0-0:96.14.0Current rate (1=day,2=night)1-0:1.7.0All phases consumption1-0:2.7.0All phases production1-0:21.7.0L1 consumption1-0:41.7.0L2 consumption1-0:61.7.0L3 consumption1-0:22.7.0L1 production1-0:42.7.0L2 production1-0:62.7.0L3 production1-0:32.7.0L1 voltage1-0:52.7.0L2 voltage1-0:72.7.0L3 voltage1-0:31.7.0L1 current1-0:51.7.0L2 current1-0:71.7.0L3 current0-0:96.3.10Switch position electricity0-0:17.0.0Max. allowed power/phase1-0:31.4.0Max. allowed current/plase0-0:96.13.0Message0-1:24.1.0Other devices on bus0-1:96.1.1Serial number of natural gas meter (in ASCII hex)0-1:24.4.0Switch position natural gas0-1:24.2.3Reading from natural gas meter (timestamp) (value)For Dave: Since it's every 10 seconds, I think it's almost impossible to totally cancel it out with a battery. Your meter might do it differently, maybe it's on a 15 minute interval.Andy Chee: The three phase import-export issue, I haven't figured it out yet, because it was not an interesting question financially (here) up until ~ 1 months ago. I think it's a very easy test, by placing a hair drier on another phase. And assumptions are nice, but I found reality much worse than that.

author: Siwastaja
author_rank: Super Contributor
timestamp: September 09, 2024, 10:13:44 am
content: If 1-0:1.8.1, 1-0:1.8.2, 1-0:2.8.1, 1-0:2.8.2 have enough resolution (some internet sources suggest resolution of 1Wh, which would be OK), you can read out 0-0:96.14.0 first to decide which two out of the four you read. Then you can read the kWh counts at the start of each integration period (which depends on country and service), and subtract from the start of the previous integration count. Done that, you can plus consumption and production together. This would probably solve the aliasing issue and give numbers in close agreement with billing.I'm here to help, I will not give in to personal attacks and terror, and will not stop discussing publicly disclosed technical problems just because you don't wish to hear the answer from a "wrong person", becauseothersmay be still interested in the solutions.I do this for a living so have some idea what I'm talking about, therefore hoping to help. Reported the abusive messages to moderators.

author: EEVblog
author_rank: Unknown
timestamp: September 09, 2024, 11:04:00 am
content: Quote from: tszaboo on September 09, 2024, 10:05:03 amShould be absolutely possible to have literally zero draw from the grid if my solar is always in excess of my draw, and at night the load is always less than the 5kW maximum. If I don't eventually see a day with zero import then I'll know somethings up...

author: EEVblog
author_rank: Unknown
timestamp: September 09, 2024, 11:06:00 am
content: Quote from: Siwastaja on September 09, 2024, 10:13:44 amPlease don't. We have better things to do than moderate petty disputes on a forum with a thousand posts a day.

author: Siwastaja
author_rank: Super Contributor
timestamp: September 09, 2024, 12:03:15 pm
content: Quote from: EEVblog on September 09, 2024, 11:06:00 amDispute implies being two-sided. I have zero idea what this guy is talking about and not any remembrance of any dispute with him. I was concerned of your forum's S/N ratio when it's filled with completely content-free messages where people suffering from random aggressive outburst out of blue start attacking others. I really hope this doesn't escalate a pattern of stalking, it's a good start already. But clearly you like it this way, your place and your rules so what I can say, well fuck you too? You had the choice to stop this offtopic. You had the choice to keep the forum engineering related and on-topic, just like my replies in this thread were. You chose offtopic and personal attacks. Well done

author: tszaboo
author_rank: Super Contributor
timestamp: September 09, 2024, 12:09:27 pm
content: Quote from: EEVblog on September 09, 2024, 11:04:00 amHere is a reddit post on how a user's Deye inverter was delayed:https://www.reddit.com/r/SolarDIY/comments/15lcjnt/deye_hybrid_inverter_pushing_power_to_grid_when/Not your exact use case, but it describes generally the speed of the inverter is reacting to varying current.

author: Siwastaja
author_rank: Super Contributor
timestamp: September 09, 2024, 12:28:45 pm
content: Quote from: tszaboo on September 09, 2024, 12:09:27 pmIf the inverter also symmetrically takes time to ramp up, then this would lead to correct net zero. The redditor thus might be having wrong expectations, we would need to see exact measurements to know.If the inverter increases feed with 2-second delay but decreases feed with 1-second delay, then the power import in the first two seconds would exceed that of export in the last second, causing a shift in net.We do battery control (one of our operating modes is net zero) and we have the advantage of knowing the "wall clock time" AND local billing policies. Therefore our control strategy differs slightly from what inverters do: they would just try to regulate momentary net power to zero. We try to regulate accumulated net energy to zero, zeroing the error accumulator whenever the billing period changes.The difference would show up in this example:Let's say this happens at night, so PV = 0.Say, inverter is capable of feeding max. 5kW.Netting period is 15 minutes.Load increases from 0 to 10 kW at 20:05, and decreases back to 0 at 20:10.Inverter's own algorithm based on instantaneous power:Inverter supplies 5kW between 20:05 - 20:10, and 0 otherwise, therefore another 5kW is bought from grid during 5 minutes, and 15-minute net balance (thus bill) is 0.417kWh import.Algorithm based on accumulating energy error:Inverter supplies 5kW between 20:05 - 20:10. After 20:10, balance is 0.417kWh on import, so algorithm continues to feed 5kW. At 20:15, this balance is satisfied, and the 15-minute net balance (thus bill) is zero.But as said many times, how terms like "smart meter" or "net metering" areexactlydefined is important.

author: coppice
author_rank: Super Contributor
timestamp: September 09, 2024, 12:47:04 pm
content: Quote from: tszaboo on September 09, 2024, 12:09:27 pmThat also highlights the need most people have for a grid connection, even if they have plenty of local solar/wind and battery capacity. The impulse response of most of this stuff isn't good enough to deal with heavy loads switching in an out instantaneously. So, your supply regulation is going to be much weaker without the grid present as a buffer. I used to live in a village which for the first few months, until the power to the village was upgraded, had supply impedance issues. The voltage didn't sit too low to be usable most of the time, but when people's (old school, pre-inverter) air cons kicked in, the resulting momentary supply droop from the high start up load made everyone else's air cons stutter, and take a high burst of current to get back up to speed. This resulted in an unpleasant interaction between these loads as they tried to recover over an extended droop recovery time. Modern electronically controlled motors mitigate this kind of effect to some extent, but there are still plenty of loads where its an issue.

author: Andy Chee
author_rank: Super Contributor
timestamp: September 09, 2024, 01:54:48 pm
content: Quote from: tszaboo on September 09, 2024, 10:05:03 amIt shouldn't be that hard to confirm, just look at your energy bill! Does your energy provider bill you for total kWh? or do they bill you kWh per phase? maybe they send you three bills every billing cycle?!

author: Siwastaja
author_rank: Super Contributor
timestamp: September 09, 2024, 02:14:21 pm
content: Quote from: Andy Chee on September 09, 2024, 01:54:48 pmIt isn't obvious from the bill. For example for me, the billing strategy changed in 2022 or so. Bill itself did not show hourly data, so you can't say - they just show total buy, total sell energy. During the old times, billing was per phase, but as those were summed into the bill this was not obvious (and I did not receive three bills).But if you added your own per-phase measurements and record the data at high sample rate,thenyou can reconstruct different ways to calculate the total sum. When you arrive close to the total values shown in the bill, then you have high chances you have found the same algorithm as used for billing.Or, you can just ask the company. Obviously they are required to disclose the exact process on which the billing is based, so you don't need to guess.

author: Njk
author_rank: Frequent Contributor
timestamp: September 09, 2024, 02:47:14 pm
content: Quote from: EEVblog on September 08, 2024, 11:18:22 pmIf you have two properties, it can be difficult for you to be at two different sites simultaneously. So yes, I'm not always there, especially at winter since it's not a big pleasure to do a construction work at that time. But it seems that guys have a monetary incentive to install as much smart meters as they can, so they're using all the tricks

author: Andy Chee
author_rank: Super Contributor
timestamp: September 09, 2024, 02:54:55 pm
content: Quote from: Siwastaja on September 09, 2024, 02:14:21 pmAs long as the provider quotes these buy & sell totals in kWh (NOT currency $ or €), that should be enough raw information to verify whether single phase export is offsetting unbalanced three phase import (or regular single phase import).The fine grained hourly data can help in chasing every $0.001/kWh, but is not needed when checking for blatantly obvious meter misconfiguration or malfunctions. (e.g. export disabled)

author: tszaboo
author_rank: Super Contributor
timestamp: September 09, 2024, 03:36:55 pm
content: Quote from: Andy Chee on September 09, 2024, 01:54:48 pmWell two things:They changed billing recently, not a lot of experience (or statements) on what this means to customers. Meters have common hardware, but their exact settings are tailored for the country they are sold in.And it depends on the algorithm, mathematically it's not that hard to see, that this below would be less advantageous for customers .Total export = Integral every 10 seconds (Export P1 + Export P2 + Export P3)Total import = Integral every 10 seconds (Import P1 + Import P2 + Import P3)It also depends on what the DSO does with the data. They are not going to keep 10s interval data, it's cumulative for ie. 15 minutes in Belgium.

author: Njk
author_rank: Frequent Contributor
timestamp: September 09, 2024, 04:09:52 pm
content: Anyway, one positive thing: The smart metering provides a lots of people with occupation. And it's better than, say, a blockchain stuff, which is a pure waste of energy with zero useful effect.

author: EEVblog
author_rank: Unknown
timestamp: September 09, 2024, 11:15:44 pm
content: 7 days in a row now where it says around 1.8kWh imported.Actual values are:2.081.382.051.691.871.931.84That's WAY too coincidental...And on none of those days has my battery gotten to 20% and cut off. And you can see that exporting significant energy, biggest peak is 15.8kWh, which means my battery got full early and there was a ton of excess. Yet still I imported 1.38kWh on that day?

author: Electrodynamic
author_rank: Regular Contributor
timestamp: September 09, 2024, 11:33:40 pm
content: I'm in Alberta, Canada and the power company installed a smart meter on my acreage about 5 years ago. The reason they gave was it saved time and manpower by being able to read the meter remotely from a grid road. Fair enough but when they came back this year to replace a power pole I quizzed the workers a bit. They agreed it's easier to read the meter remotely and not have to enter my property and deal with dogs and stuff.Then I said "I assumed you guys installed smart meters everywhere because variable rates and peak rate pricing was coming". He just smiled, then said you can be sure that's the next step.The power companies also pulled a fast one here. The politicians like to brag about how cheap power is here and it's pretty reasonable at $0.12/kwh with a rural contract. What they don't say is the power companies have quadrupled the maintenance and administration fees to compensate for lost revenue. So now it's common for some people I know to see a $250 power bill for only using $50 worth of power.I think they may have done this to indirectly penalize people with or thinking about installing small solar installations. So we can produce all the solar power we want to offset our power use but maintenance/administration fees plus peak rate pricing would all but ensure nobody makes a dime.

author: Andy Chee
author_rank: Super Contributor
timestamp: September 09, 2024, 11:54:11 pm
content: Quote from: EEVblog on September 09, 2024, 11:15:44 pmDo you have access to your energy provider's version of the same data?For example, my energy provider (Jemena) has a website where I can login to get my interval data, like so:Not sure if your provider (Endeavour?) gives you a similar web page.

author: EEVblog
author_rank: Unknown
timestamp: September 10, 2024, 12:04:03 am
content: Quote from: Andy Chee on September 09, 2024, 11:54:11 pmNope, nothing. AGL is the provider, but Endevour is the physical supplier.

author: Andy Chee
author_rank: Super Contributor
timestamp: September 10, 2024, 12:09:36 am
content: Quote from: EEVblog on September 10, 2024, 12:04:03 amAGL is also my biller, but Jemena is my physical supplier.Not sure whether NSW is different to VIC in this respect, but I got my interval data through Jemena.

author: Andy Chee
author_rank: Super Contributor
timestamp: September 10, 2024, 12:12:29 am
content: Well that's inconvenient!https://www.endeavourenergy.com.au/your-energy/your-electricity-meter/how-to-read-your-meterQuote

author: EEVblog
author_rank: Unknown
timestamp: September 10, 2024, 12:22:34 am
content: Quote from: Andy Chee on September 10, 2024, 12:12:29 amJust filled it out."Data will be provided within 10 business days upon receipt of a valid request."

author: Someone
author_rank: Super Contributor
timestamp: September 10, 2024, 12:29:01 am
content: Quote from: EEVblog on September 10, 2024, 12:22:34 amAt one point providers were only providing data begrudgingly, in spreadsheets for the specific requested period. No API or web interface. But it met their obligation to provide it.

author: EEVblog
author_rank: Unknown
timestamp: September 10, 2024, 12:45:02 am
content: Quote from: Someone on September 10, 2024, 12:29:01 amThat's what it sounds like, they have to do it due to regulation, but no mention is made of how easy it has to be. I expect to get a CSV file or something if I'm lucky.

author: Njk
author_rank: Frequent Contributor
timestamp: September 10, 2024, 05:22:37 pm
content: BTW, it must be relatively easy for the utility (or for those operating the meters) to verify that the meter is located at the particular customer premises and is not stolen. That makes the utility well positioned not only to sell energy to subscribers but also to provide the client authentication service to interested parties.E.g. the subscriber puts his private key to the meter (provided the meter will never leak it). Then, during a banking operation, for instance, the client sends a signed request to the bank that naturally wishes to verify the signature. To do so, the bank generates auth challenge message that also includes a one-time symmetric key, encrypts the message with the client's public key and sends it with the client ID to a known auth center where the utility is registered. The center identifies the utility to forward the message to. The utility, in turn, forwards it to the client's meter that can perform the verification as it possesses the client' private key. The meter, in the reverse way, communicates the response message encrypted with the symmetric key back to the bank. Something like this.

author: coppice
author_rank: Super Contributor
timestamp: September 10, 2024, 08:36:00 pm
content: Is this an issue like the one described in another current thread, where the poor impulse response of the inverters allows substantial gulps of energy to be pulled from the grid to stabilise the local voltage? 2kWh per day seems a lot for that, but if some bursty appliances keep causing these gulps it doesn't seem impossible. Dave should attach a power quality analyser at the point of metering, and trace what is really happening moment by moment to the power flow. Unless he has disposed of it, he had a pretty nice Voltech analyser, as long as he has the necessary PC software to go with it It lacks its own graphing screen.

author: tszaboo
author_rank: Super Contributor
timestamp: September 10, 2024, 09:04:47 pm
content: Quote from: coppice on September 10, 2024, 08:36:00 pmHe has a CT for the house, he can double probe that.It might be just an offset. But yes, 2KWh sounds like a lot, but it's only 360mA on the 30 or 50A or however much the connection is. So about 1% full scale.

author: rteodor
author_rank: Frequent Contributor
timestamp: September 10, 2024, 09:24:21 pm
content: Maybe Deye has some setting like Victron does ?50W setpoint amounts to about 1KWh / day.Later edit: simple test: on a good day turn the breaker to the inverter off and see if that residual consumption is still there.

author: EEVblog
author_rank: Unknown
timestamp: September 10, 2024, 11:35:30 pm
content: Quote from: rteodor on September 10, 2024, 09:24:21 pmIt does, set to 5W

author: Siwastaja
author_rank: Super Contributor
timestamp: September 11, 2024, 05:36:11 am
content: Quote from: tszaboo on September 10, 2024, 09:04:47 pmCan confirm. 2kWh/day = merely 83W. We sell a box which does battery control among other things and measures phase currents with those typical cheap Chinese CTs (like everyone else), and around 50-100W would be a typical offset number for our design, still less than 1% full scale.Even if one developed a super accurate and expensive meter, it would still show an offset compared to the utility meter because those are not infinitely accurate either. Best is to get data integration with the utility meter (interfaces and their availability vary by country and grid company) because then you can feed the adjustment algorithm with the exact same data that gets used for billing - even if it's not completely accurate either. Our box has this option here, but inverters do not.Or just accept there's going to be a small offset.

author: Jeroen3
author_rank: Super Contributor
timestamp: September 11, 2024, 06:46:16 am
content: Inverters have a maximum power ramp for grid code. How much is this in AU?Those grid energy meters are supposed to be accurate up to 0. something %, that like a few hundred Wh per month deviation.My money on the excess export is on dodgy software in the inverter. I mean, DEYE isn't known for the honesty. (see german scandal)

author: rteodor
author_rank: Frequent Contributor
timestamp: September 11, 2024, 06:58:08 am
content: Quote from: Jeroen3 on September 11, 2024, 06:46:16 amI would think so too. If I watch grid consumption during the night when the mains is more quiet, that value swings from 20W to 80W all the time. During the day when more loads are coming and going from the grid that swing grows to like -30W (export!) to well over 100W.Maybe Deye is built differently but regulation within 5W margin is not easy.

author: Siwastaja
author_rank: Super Contributor
timestamp: September 11, 2024, 07:05:56 am
content: Quote from: rteodor on September 11, 2024, 06:58:08 amIt's cheap electronics engineered to pinch the last penny, it's not like control accuracy of 1%FS or so isthatbad - but it still feels wrong and causes real loss of money. The problem as I see is not the cheap-assery of these products in itself, but how much their price increase in the whole chain when you include sales, install work, etc, with each step marketing them more gloriously and adding their own profit, causing customer unhappiness over the price - quality ratio.

author: coppice
author_rank: Super Contributor
timestamp: September 11, 2024, 01:44:20 pm
content: Quote from: Siwastaja on September 11, 2024, 07:05:56 amThe problem is a large amount domestic consumption is at around something like 1% of full scale. So, if you are only accurate to 1% of full scale you may have a 100% error for much of your consumption. There is not excuse for this in 2024, when an energy metering chip that achieves better 1% accuracy over a 1000:1 range is 20 to 30 cents, and the sensors for it need not cost a lot.

author: Siwastaja
author_rank: Super Contributor
timestamp: September 11, 2024, 02:39:04 pm
content: Quote from: coppice on September 11, 2024, 01:44:20 pmI agree 1%FS is not that great. Then again, 1% accuracy (of value) over 1000:1 range implies 0.001%FS error. I won't buy this claim, especially when you consider real-world AC measurement which requires phase voltage sensing and quite high sampling rates, no phase shift etc. as real world current waveforms have distortion and harmonics.The reason why inverter manufacturers (and we!) use current transformers is they offer an easy way for retrofit building net metering without having to disconnect and reconnect the main supply phase lines, possibly having to add another box on the wall where to mount a "proper" meter. This, with extra work involved, is easily 200-300EUR worth, so whether a chip costs 20 or 30 cents is totally irrelevant.We are hoping that utility meters with data output become more commonplace. The transition is currently happening here. The utility meter is both more accurate, and even when it isn't, it's the one used for billing so using the same data for battery control results in zero offset in billing.

author: coppice
author_rank: Super Contributor
timestamp: September 11, 2024, 03:26:40 pm
content: Quote from: Siwastaja on September 11, 2024, 02:39:04 pmThey can't achieve 0.001% accuracy when the load is full scale. Temperature coefficients wouldn't allow that, and calibration would be a nightmare to achieve. They achieve better than 1%, and often easily achieve 0.1%, over 1000:1 range, with a fairly constant error across most of that range. When you get down to really low currents CMRR, and other forms of crosstalk, start to spoil the results. Just look at any app note for an energy metering chip, and the real world results they show. The IEC specs for utility energy meters don't call for maximum accuracy over such a wide range, but its easy to achieve these days.QuoteIf you want a completely non-invasive fit, then accuracy will be limited with a clamp on current transformer. However, if you can disconnect a wire, and slip a CT over it, you can achieve high accuracy over a wide dynamic range. Cheap CTs, driven by the utility meter market, have massively improved in the last 2 decades. One that's DC tolerant up to 10A, with a maximum current of 100A, and maintains it phase and amplitude accuracy down to <100mA is less than a dollar these days.QuoteUtility meters don't really cut it when looking for issues that might be very dynamic in nature, like the impulse response of local generation kit. They are engineered to give longer term information. However, the components they are built from can be used to give the kind of dynamic results you need.

author: Electrodynamic
author_rank: Regular Contributor
timestamp: September 11, 2024, 03:33:04 pm
content: rteodorQuoteI agree, I built and tested my own no import/no export programmable hybrid inverter system logging volts, amps, power, energy, frequency and PF. I also tested no export load swapping to power water/space heaters and sand thermal storage.The problem comes down to resolution and lag time. So by the time my microcomputer measured all the data, made all my calculations and sent the commands to the inverter section the power values had already changed. I found large fast changes in power like AC motor inrush current tend to produce the greatest error rates. The greater the rate of load change or system lag the greater the error rate. I found it very difficult to reduce the lag time and one option is to use a low power always export setting. So we always export a small amount say 50w to compensate for the system lag. If we do import we keep increasing the min export setting until we stop importing if that's important to the user.I also think the smart meter works against us in a hybrid limited import mode like what EEVblog seems to be doing. From what I gathered the smart meter logs the import and export power separately. So if you do import power you cannot take it back by exporting later, it's a one way street and keeps accumulating. This is also handy for the utility companies to check on what kind of equipment there customer might be operating. If an export reading ever shows up on the smart meter they know about it.

author: Siwastaja
author_rank: Super Contributor
timestamp: September 11, 2024, 03:41:12 pm
content: Quote from: Electrodynamic on September 11, 2024, 03:33:04 pmAgain, the key question is how import/export is being billed. What I hate in these discussions and product design in general is that companies produce solutions and people discuss them without first defining at all what theyshoulddo i.e. requirements. This drives us to solve wrong problems or maybe completely nonexisting problems.For example if billing is based on net (import + export) over some sensible time period (5 minutes, 15 minutes, hour...) then all those control dynamic issues become trivial, just keep a running count of net and adjust power to zero it out. Even if your impulse response were asymmetrical (e.g. take 1 second to ramp up and 5 seconds to ramp down) even that doesn't matter, then.But to do something like this we first need toknowwhat are the billing criteria and because they vary by country and time and are sometimes hard to find out, it is hard for product designers to write algorithms for.

author: coppice
author_rank: Super Contributor
timestamp: September 11, 2024, 03:53:07 pm
content: Quote from: Siwastaja on September 11, 2024, 03:41:12 pmMost metering measurement units are used in one of 2 ways. One way is the meter takes per second energy results from the measurement unit, and accumulates them according to the direction of the net energy flow over that second. A few meters actually accumulate in 4 quadrant bins, rather than 2 half-plane bins. The other way is they work from the energy pulses. Those 1000/kWh or 1600/kWh type pulses that usually flash an LED these days. These give a somewhat longer average of the energy flow, unless the load is high, but they do properly integrate any moments of import vs export through the pulse period. I think most people work from per second measurements from the front end these days.

author: rteodor
author_rank: Frequent Contributor
timestamp: September 11, 2024, 05:21:10 pm
content: Quote from: coppiceVictron is well known fornotcutting corners and still can't - or won't do it more precisely than 50W residual. Accurate measuring does not make it for good grid regulation.Quote from: Electrodynamic on September 11, 2024, 03:33:04 pmWow. Did you do it alone for yourself or part of a bigger project ?Quote from: Electrodynamic on September 11, 2024, 03:33:04 pmWhat I find strange in Dave's case is the amount of energy imported when compared with my case. I left the system for a full month with no consumption other than the residual. The meter counted just under 30KWh. That mean my awg. residual is 41W. But Dave is exporting, probably at least 8h/day and still has 1.3KWh/day awg. - if I remember correctly!?. That means the residual power would be double, like 82W. Now I think maybe also the smart meter makes its count a bit "conservative" because I expect that the Deye inverter does not perform that worse as it consumes mostly at night.Quote from: coppice on September 11, 2024, 03:53:07 pmThe meter reading guy warned me that with the type of meter I have any export will be billed as consumption. Based on his knowledge of real cases.

author: coppice
author_rank: Super Contributor
timestamp: September 11, 2024, 05:34:22 pm
content: Quote from: rteodor on September 11, 2024, 05:21:10 pmThere are anti-tamper meters which intentionally read energy as consumed whichever way it flows. I think some of the simple energy measurement chips, which simply output a number of pulses per kWh, may not differentiate which way the energy flows. Its a while since I looked at that, and I'm not sure now. Any energy measurement chip sophisticated enough to do more than just generate energy pulses shouldn't be doing that.

author: uer166
author_rank: Super Contributor
timestamp: September 11, 2024, 05:55:15 pm
content: Quote from: coppice on September 11, 2024, 01:44:20 pmAs someone who designed smart meters: there's way more to it than this. It's not "$0.2-$0.3" for this kind of dynamic range. There's usually a decently small offset error (certainly less than 1% of FS), and a 1-2-3% error or so that's guaranteed on a much smaller dynamic range. The specific accuracy depends on the load PF, crest factor, etc. There shouldn't be a 80W offset error for a smart meter, but then again we're not talking about a MID certified meter, rather the internals of the Deye inverter that might cause that fixed import.

author: Siwastaja
author_rank: Super Contributor
timestamp: September 11, 2024, 05:56:14 pm
content: I find this whole discussion odd, as if you all lived in a chaos. I mean, I can easily explain how this all works in Finland no problem, and have done so before. Finland can't be an exception, don't you have any means to figure out the rules in wherever you live?I mean, you can't your buy a PV system / battery inverter and connect it to grid without asking anyone and then start wondering how that might affect your billing or how your energy is measured, can you? At least here you need apermitfrom the grid company and at that time they check whether the local distribution can handle your export. (This "permit" being a very lightweight process, more like installer just notifying about it). And quite obviously during that permit or notification process they also would make sure that the energy meter at your premise is recent enough so that it can measure import and export and and report that data automatically to the grid operator. In Finland all meters were upgraded to support this probably more than 10 years ago but some early adopters of PV might have required a meter swap, basically putting them earlier in the line of meter changes.And now we are in the process of thesecond setof meters that support separate import/export metering. Simply because meters have some technical lifetime. Maybe they are getting out of calibration guarantee timeframe, or maybe this is needed to transition into 15-minute net periods, maybe the older meters from 10-15 years ago only support hourly logging, I don't know exactly. And the new meters have the so-called H1/P1 port, basically a one-way open-collector UART giving ASCII data every 10 seconds, for data integrations into control systems. But no inverter I'm aware of supports it, our control box is one of the few that does. But at least having it available is solving other half of the chicken-egg problem.So can you do these battery installs without permit and if you can then I think the best would still be to call the grid operator and ask how their billing rules work, is there netting or not and if yes, over what time period?And if someone still has such ancient meter that it cannot read export at all (or wrongly reads it as import), then it would beobviousyou need a meter swap when getting a PV or hybrid inverter or even just a battery inverter because of the dynamics mentioned causing short-time export.

author: uer166
author_rank: Super Contributor
timestamp: September 11, 2024, 06:02:14 pm
content: Quote from: rteodor on September 11, 2024, 05:21:10 pmThis is surprisingly reasonable. IIRC PG&E will actually fine you for it some much larger $$$ if you export without an agreement.

author: rteodor
author_rank: Frequent Contributor
timestamp: September 11, 2024, 06:30:58 pm
content: Quote from: Siwastaja on September 11, 2024, 05:56:14 pmYou clearly have no idea what 50 years of forced communism did to people's minds.

author: tszaboo
author_rank: Super Contributor
timestamp: September 11, 2024, 06:51:17 pm
content: Quote from: uer166 on September 11, 2024, 05:55:15 pm1% total error for the Deye inverter and the smart meter.Smart meters exist with 2%, 1%, 0.5% and 0.2% specifications.What they install here is domestically Class A, which is 2% accurate. Which is 2% of range. You don't like it, too bad, the DSO doesn't care, nobody understands what it means to care. If you talk about it, you are met with empty stares from people because they have no idea what statistics or "error in measurement" mean. it could be easily 2KW/day, meaning 160 EUR a year for the entire lifetime of the meter.When I had my hot water meter replaced, my consumption magically went down 30% in a year. Which is hundreds of EUR in a year. Also don't look up gas meter accuracy.Don't complain, be a good sheep.

author: coppice
author_rank: Super Contributor
timestamp: September 11, 2024, 07:12:59 pm
content: Quote from: uer166 on September 11, 2024, 05:55:15 pmAs someone who designed smart meters, its 20 to 30 cents for a chip that does basic functions, and about 50 if you want active, reactive, voltage, current, etc. measurements with 1000:1 range at 0.5% accuracy or better. Who charges more? The parts you need in addition to the measurement chip are mostly cheap. If you want a shunt sensor with a great temperature coefficient that another 20 cents, but for what we are talking about you can use something cheap if you don't need maximum accuracy. If you need isolation that can add a bit, but in the types of products we are looking at, much of the circuitry is connected to the live area, and metrology can be dropped in there.Outside the US the relevant specification is IEC62053. This defines the accuracy requirements for energy meters to meet what is termed class 0.5, class 1 and class 2. These basically mean 0.5%, 1% or 2% accuracy over the bulk of their operating current range, and a fairly wide power factor range. The spec relates everything to a basis current, which is only a fraction of full scale, but full scale is not defined. Most utilities use 6 times basis as full scale, although some use 10, 12, or even 20. Lets take 6. So, a typical domestic 230V 60A meter has a basis current of 10A. Its a weird way to express an operating range, but that's how it is. Let's take a class 1 (1% accurate) meter. The spec says the meter must be 1% accurate from full scale down to 10% of the basis current, at unity power factor, and down to 20% of the basis current for power factors between 0.5L and 0.8C. It must be 1.5% accurate between 5% of the basis current at unity power factor, and 10% of the basis current for power factors between 0.5L and 0.8C. Below this they don't specify, but no utility will accept a meter with more than a few percent error at its cutoff point, called the anti-creep threshold or starting current. This is 0.4% of the basis current. Below this threshold the meter must not accumulate energy. This is to prevent noise causing the meter to creep on no load, and create bogus consumption for unoccupied buildings. If you do, you have a customer service nightmare.So, the typical domestic 230V 60A class 1 meter will read anything above 40mA with reasonable acuray, although this is usually implemented as a power measurement, so it ends up dependent on the power factor. Using power helps with noise tolerance. 40mA at unity PF is 9.2W. The meter must read with decent accuracy from 9.2W up to 13.8kW (60A at unity PF), and meet the accuracy template in the IEC spec from 0.5A upwards. In reality, with current metrology solutions, any well designed meter should be 1% accurate from starting current to full scale over a wide power factor range, and a reasonable temperature range. This is now cheap to do, including the related calibration of the sensors. If non-metering products are not achieving results like this, they really need to get their act together.

author: coppice
author_rank: Super Contributor
timestamp: September 11, 2024, 07:17:34 pm
content: Quote from: tszaboo on September 11, 2024, 06:51:17 pmA utility meter's energy measurements are not specified as a percentage of range, but as a percentage of reading, as I described in my previous message. If the meter has supplementary functions, like current and voltage measurements, those are typically specified as a percentage of full scale, but the energy measurement accuracy is not.

author: Andy Chee
author_rank: Super Contributor
timestamp: September 11, 2024, 07:33:06 pm
content: Quote from: Siwastaja on September 11, 2024, 05:56:14 pmIn Australia, the push back against meter upgrades was quite significant. Of course there were the usual conspiracy theories surrounding radio waves and brain cancer, etc.But the biggest reason for the reluctance, is that the cost of the meter upgrade was to be paid by the consumer, not the power company.https://theconversation.com/smart-meters-dumb-policy-the-victorian-experience-47685https://stopsmartmeters.com.au/Even to this day, there are many areas of Australia still not converted to smart meters.That being said, I do believe that anyone installing solar panels with export capability, are generally not permitted to retain ancient dumb meters.

author: uer166
author_rank: Super Contributor
timestamp: September 11, 2024, 07:44:24 pm
content: Quote from: coppice on September 11, 2024, 07:12:59 pmI agree with most of this analysis other than cost. DC-tolerant CTs or shunts that can handle 5kA surge are not that cheap. And of course a "1%" classAB meter can have error much larger than that for bad PF loads. I've designed for EN50470 (MID metering) specifically which seems relayed to your standard.

author: coppice
author_rank: Super Contributor
timestamp: September 11, 2024, 07:59:40 pm
content: Quote from: uer166 on September 11, 2024, 07:44:24 pmMaybe you use the wrong suppliers.People like VAC charge quite a lot in modest quantities. I don't know what they are like for production volumes. However, you can buy CTs from Chinese suppliers than beat VAC on every performance parameter for a very reasonable price. 20 years ago that was not the case, but from over 10 years ago it has been.When the power factor gets below about 0.2 even expensive power analysers start struggling to maintain high accuracy. You really need to match the phases of your voltage and current sensors to a very high accuracy for that kind of power factor.

author: uer166
author_rank: Super Contributor
timestamp: September 11, 2024, 08:06:10 pm
content: Quote from: coppice on September 11, 2024, 07:59:40 pmWe ended up doing a per-phase calibration of the inter-sensor delays. It was a nightmare but overall avoided needing expensive phase-matched input anti-aliasing filters!

author: coppice
author_rank: Super Contributor
timestamp: September 11, 2024, 08:11:33 pm
content: Quote from: uer166 on September 11, 2024, 08:06:10 pmQuite a lot of meter designs screw up those filters, by not keeping them impedance balanced. They work great at room temperature, but the phase shift goes way off as the temperature changes, because most capacitors are not that thermally stable. Get them balanced and any old capacitors will do.

author: tszaboo
author_rank: Super Contributor
timestamp: September 11, 2024, 08:13:14 pm
content: Quote from: coppice on September 11, 2024, 07:17:34 pmWell thanks for correcting me, I learned something.But you agree that with low currents, cancelled out with ie a home battery the error will be higher than 1 or 2%.

author: Njk
author_rank: Frequent Contributor
timestamp: September 11, 2024, 11:02:04 pm
content: Literally:

author: EEVblog
author_rank: Unknown
timestamp: September 11, 2024, 11:02:51 pm
content: I've changed the Grid Trickle Feed setting from 5W to 50W, I'll give it a few days and see what happens.

author: Siwastaja
author_rank: Super Contributor
timestamp: September 12, 2024, 06:22:40 am
content: Quote from: coppice on September 11, 2024, 07:12:59 pmAgain, as a meter designer don't be fooled by the BOM cost of the meter. It's not like an inverter manufacturer could just add those components on the inverter's main PCB. Due to physical requirements the grid point net meter has to be separate. Even if inverter manufacturer started to manufacture their own meters (some do, e.g. Kostal offers both inverters and meters) it is unlikely they could significantly cut prices compared to existing MID compliant meter manufacturers.The cost of the chips or current sensors in the meter is irrelevant, customer pays for the market price of the meter which is much more than BOM, plus extra install work, which is always at customer's site. These invertersalreadyoffer two options for the grid point net metering: using a MID certified (with any accuracy you want) meter using RS485 wiring, or clamp-on CTs. The former option is approx. 150-300EUR more expensive (install cost included), not some cents.Probably the sweet spot in cost would be to algorithmically improve low-load offset errors, at least if the inverter manufacturer thinks they will be selling in large numbers to compensate for the NRE cost.Thanks for explaining the accuracy details, the information is not too easy to find without diving deep into the actual standards. % of value indications are most misused metrics, they always require extra attributes like some minimum threshold, otherwise they always imply infinite accuracy and as such are impossible.One thing to remember is that offset issue is not only at low loads. Say we have two meters which are provably +/-1% accuratein value, so MID compliant (was it class B for 1%, I don't remember). Now let's say one meter is used for billing, other for inverter control, and your consumption is 2000W for 12 hours a day (whatever clothes washing, air conditioner use, cooking). One meter shows 1980W, another 2020W. 12 * 40Wh = 0.5kWh of unwanted import or export is thus billedeven if offset error at low loads was completely absentandeven when metering is utility-level accurate and compliant to billing requirements. And this 0.5kWh would be enough for some people to complain. So for true no-import-when-production-exceed-consumption, data integration to the meter which does the billing is a must. Even if you designed a perfectly accurate to 0.0001% meter, it won't help because the existing billing meter is not that accurate.

author: IanJ
author_rank: Unknown
timestamp: September 12, 2024, 06:30:08 am
content: Just a note……When I decided to build my own centralized home energy monitoring thing I passed on CT’s (current clamps) and went for a proper meter with RS485/modbus output.CT’s are sooooo easy to fit but meh!https://owen-brothers.com/singlephase/direct-connected-mid-approved/ob418-multi-function-100a.htmlIan

author: coppice
author_rank: Super Contributor
timestamp: September 12, 2024, 12:03:23 pm
content: Quote from: IanJ on September 12, 2024, 06:30:08 amYou conflated two things there - CTs and clamps. Clamp on CTs are not the greatest thing. They aren't the most stable things, even if you keep the jaws clean. Ring CTs are a whole different matter. They are very stable, and the norm for high current AC measurement.

author: Siwastaja
author_rank: Super Contributor
timestamp: September 12, 2024, 12:26:24 pm
content: Quote from: coppice on September 12, 2024, 12:03:23 pmYeah. With non-clamp types, I would be more concerned about phase shifts and frequency response, than the 50/60Hz AC accuracy. And this of course includes the whole chain of processing.Also coupling of 50/60Hz AC voltage into current measurement signals causes AC drift which is not easy to calibrate out because unlike random noise, it's in perfect sync with voltage measurement and therefore acts like real export or import power.

author: coppice
author_rank: Super Contributor
timestamp: September 12, 2024, 01:53:31 pm
content: Quote from: Siwastaja on September 12, 2024, 12:26:24 pmCT phase shifts are an interesting issue in utility meters. When you have a small meter with CT sensors - say a 60A 3 phase meter for a small workshop application - the phase shift of the CTs gets properly calibrated out at the factory. When you have a bigger meter, like the numerous 6A 3 phase meters intended for use with large external CTs, those external CTs are mixed and matched, without individual calibration. Most meters only seem to allow the multiplier factor to be set. No tweaks for the small but often significant phase shift of the external CTs are usually provided. So, these meters cannot give very accurate results at poor power factors. I have a Voltech PM1000+ power analyser, which can measure 20A internally. For higher currents, or temporary attachment with a clamp on sensor, Voltech supplied optional CTs. They documented the phase shifts of these sensors, but the analyzer has no facility to tweak the phase correction. They only provided for the scaling factor of the sensor. People often do a poor job with these measurements.As for the leakage of the voltage signal into the current signal, this is mostly a CMRR issue. If you use a modern metrology device with switch capacitor sigma-delta converters the CMRR can be huge, and any leakage is almost always a PCB or wiring issue, and solvable by anyone competent. When you use other kinds of ADC, like SAR or continuous time sigma-deltas, or put amps and other complexity in the signal chain, the CMRR can be a limiting factor.

author: EEVblog
author_rank: Unknown
timestamp: September 16, 2024, 11:31:14 pm
content: Quote from: EEVblog on September 11, 2024, 11:02:51 pmAfter 5 days is made an average difference of 0.35kWh/dayIt it really was a 45W increase, over 24hrs that would equal 1.08kWh/daySo I'm not sure that's the problem, but there is an increase there, soI've changed it back to 5W today.

author: EEVblog
author_rank: Unknown
timestamp: September 18, 2024, 12:28:04 am
content: Just discovered I can download the data from the energ provider website!Annoyingly with alternating fields for solar and usage, so I need to split out every 2nd row to analyse the data, but I get 30min interval data.

author: EEVblog
author_rank: Unknown
timestamp: September 18, 2024, 12:37:55 am
content: Two different days, showing it can actually go to zero.

author: IanJ
author_rank: Unknown
timestamp: September 19, 2024, 08:34:02 am
content: Quote from: EEVblog on September 18, 2024, 12:37:55 amWhen discharging my battery I notice I am importing between 5 and 10W. Seems to wander up & down every few seconds. Haven't noticed if it goes to zero at all though.Am no expert, but here's my off the cuff theory:Reactive Power Compensation (VAR): Import a small amount of power to manage reactive power in the system, maybe to maintain power quality and manage fluctuations in voltage.Exporting real power, the inverter may still import reactive power to compensate for local voltage issues or grid stability.Some equipment in the home may require reactive power, especially motors, HVAC systems, or anything with inductance or capacitance.Via the Solis Inverter API I can read the Inverter Reactive Power value.....haven't actually tried it yet to see what sort of values it produces. There are also limits I can set........hmmmm!Ian.

author: coppice
author_rank: Super Contributor
timestamp: September 19, 2024, 04:22:14 pm
content: Quote from: IanJ on September 19, 2024, 08:34:02 amA grid connected inverter is playing a constant balancing act, pushing out just enough power to meet the immediate need. There is going to be some tolerance in this, and maybe that tolerance is 5 to 10W. Also, as the demand changes, the impulse response of the control loop is going to allow some momentary exchange of energy in one direction or the other, and again that may show up as your few watts of residual exchange.

author: EEVblog
author_rank: Unknown
timestamp: September 20, 2024, 12:46:55 am
content: Quote from: coppice on September 19, 2024, 04:22:14 pmYes, the only way around this is to switch off the grid connection at night when you are using the battery. Maybe a bigger (or multiple?) inverter would make a difference. In my case I've got one 5kW inverter that powers the house at night, load loop response time unknown.

author: bsdphk
author_rank: Regular Contributor
timestamp: September 22, 2024, 04:04:52 pm
content: Have you already made a sanity-check, to find out if your provider is reading the correct smart meter ?It is not unheard of that meter numbers get mucked up one of the many ways it can happen.For "typical households" that can go on for years before anybody notices, and the curves you show do not look totally unreasonable for a normal household where nobody is home during the day.ALso: Consider talking directly to the meter via the optical port?

author: Bryn
author_rank: Regular Contributor
timestamp: September 22, 2024, 04:30:08 pm
content: I never bother with smart meters... one engineer from a gas company we were with years ago tried to convince us with one until he had to agree with my mother that it's no point (given that it's only two of us in the house and we don't burn a lot of energy on average).Now, I have British Gas trying to persuade me with getting one but I hear they're not all that reliable and not many work. Plus, they're too much of a distraction and would make you feel more paranoid of how much energy you're using, just to "save the planet" 🙄

author: Electrodynamic
author_rank: Regular Contributor
timestamp: September 22, 2024, 05:37:33 pm
content: I suspect the error is in the smart meter time resolution.I remembered that when I was data logging measurements the time resolution really came into play. So as an Engineer I always want max data down to the millisecond however the data file then become massive and unmanageable. One measurement every 0.1 seconds gives us 864,000 measurements in 24 hours or 26,000,000/month. So we compromise and say every few seconds is enough. However the last value is then held for a few seconds regardless of the current value giving us misleading measurements. We can average the values but this is still inaccurate and simply adds two values and divides by two.Now add in dirty power, transients or inductive spikes where the higher value is held for a few seconds despite the current value and the errors starts accumulating over time.An internet search claims smart meters measure power every 1 to 5 seconds for real-time data and 15 minutes for average consumption data. It's also claimed household power consumption profiles can have different recording intervals (1, 10, 15, 30 and 60 min) and different reporting periods.I have a feeling the claimed "measurement accuracy" could relate to the sensor accuracy which has nothing to do with the time resolution. The sensors could be 99% accurate in one instance but if the time resolution is 60 seconds the total accuracy is still low. The more I read about smart meters the less I like them and the accuracy sounds like a crap shoot in my opinion.

author: Monkeh
author_rank: Super Contributor
timestamp: September 22, 2024, 06:22:15 pm
content: Quote from: Electrodynamic on September 22, 2024, 05:37:33 pmI think perhaps rather than an internet search you should review the standards which set the requirements for metering. Digital meters have been around for decades and nobody is raising concerns about their billing accuracy (some probably did in the early days, of course.. but we didn't have an internet FUD machine to fan the fires of ignorance back then), so what makes you believe the same thing with a radio is worse?

author: nali
author_rank: Frequent Contributor
timestamp: September 22, 2024, 07:01:21 pm
content: Dave's meter probably contains an AD metering IC, something like AD7757. The metering is continously done on-chip, the MCU gets an interrupt pulse for either active or reactive power and just does the counting. No idea where this 15 second malarkey comes from.https://www.analog.com/en/products/ade7757a.html#part-details

author: IanJ
author_rank: Unknown
timestamp: September 22, 2024, 07:36:26 pm
content: Quote from: Bryn on September 22, 2024, 04:30:08 pmWhen you are on that side of the fence that’s exactly how they appear, I’ve been there, but when you switch and especially for electricity the benefits are big……like dynamic tariffs throughout the day allowing you to capitalize and even earn out of it.Ian.

author: Electrodynamic
author_rank: Regular Contributor
timestamp: September 23, 2024, 09:10:39 pm
content: MonkehQuoteMy experience comes from my place of work where we have a wide area secure LAN with over 10,000 points and digital metering up the ying yang. In theory once calibrated everything should work as expected but in reality it seldom does. Reality is messy and at any given time maybe ten percent is out of calibration or out of service. You could take ten pieces of identical supposedly calibrated metering equipment and get ten different readings after 6 months.The problem is that many people not in the automation/controls industry or operating this kind of equipment daily have false expectations about reliability and accuracy. Like the appliance guy repairing equipment daily versus the buyer who thinks his new appliance is actually going to make it's warranty. So I would like to think the manufactures and most tech's know what there doing but all the evidence I have seen suggests this isn't the case. I mean, if everything should work as claimed in theory then why does everything tend to turn into a train wreck?.

author: Someone
author_rank: Super Contributor
timestamp: September 23, 2024, 10:23:59 pm
content: Quote from: Electrodynamic on September 23, 2024, 09:10:39 pmYou presented a theory:Quote from: Electrodynamic on September 22, 2024, 05:37:33 pmWhich is pure imagination at this point. Smart meters are billing from energy accumulators, not some periodic sample and hold. Otherwise there'd be a box to grab power on the non-metered cycles and avoid the billing.

author: coppice
author_rank: Super Contributor
timestamp: September 23, 2024, 11:04:33 pm
content: Quote from: Someone on September 23, 2024, 10:23:59 pmSimple meters that merely accumulate net exchanged energy have no time issues. Ones that accumulate in separate bins for import and export, 4 quadrants, or other multi-bin schemes can have a sampling time element in their behaviour with dynamic loads. However, I have never seen one where time resolution below 1 second will make any difference.

author: EEVblog
author_rank: Unknown
timestamp: September 23, 2024, 11:21:32 pm
content: For those playing along at home.Still getting some very large solar feed-ins even with the 25kWh battery.Expect this to rise even more come summer time.I guess I really need a plan that pays the best feed-in tarrif.EDIT:https://www.ipart.nsw.gov.au/solar-feed-tariffs-nsw-1

author: Siwastaja
author_rank: Super Contributor
timestamp: September 24, 2024, 05:35:16 am
content: Quote from: coppice on September 23, 2024, 11:04:33 pmYeah. Any modern meter would meter to separate "bins" or "registers" for import and export, real and reactive power.At any single point in time, there is only "power", a 1-dimensional scalar value, the physical quantity: P = E/dt = U*I.But a modern meter can then choose to accumulate the value in a separate counter based on the sign. As meters would sample at least thousands of times per second, during any longer time period (even just 1 second) there can be both import and export. Now the key question is, how is this billed? Now this stops being physics and engineering, and becomes an arbitrary choice and varies by country, region, company, sometimes there is legislation involved, sometimes just convention. And it seems that knowledge and discussion always stops here. Many are well able to explain how the energy registers are accumulated, but given place X on Earth it seemsno oneknows how that data is used to calculate the billing. Which is weird because usually people are quite interested in their contract terms and reasoning for their bills, like you wouldn't accept buying bananas and getting a random bill and then just speculate over the Internet about potential accuracy issues in the amplifiers used in digital scales.I'm nearly able to answer how it works in Finland: on some customers, net (import + export) is calculated for each hour, resulting in one scalar for that hour. For others, the net is calculated for each 15 minutes, resulting one scalar for 15 minute period, or, if looked at hourly data, both import and export on same hour is again possible. This means you can export excess PV to grid at 1kW for 7.5 minutes and then import 1kW for another 7.5 minutes and be billed for zero. Then again, even I don't know if I'm being billed on the 1-hour or 15-minute net period.

author: Siwastaja
author_rank: Super Contributor
timestamp: September 24, 2024, 05:40:55 am
content: Quote from: Electrodynamic on September 23, 2024, 09:10:39 pmYou are just being delusional. But worry not - energy meters are fairly simple devices which measure both voltages and currents within the single box, directly interfaced to a specific measurement IC or a microcontroller which performs the power calculation. The performance is also tightly regulated by legislation (e.g. in EU, MID directive). Any internal timing is definitely a non-issue, I can assure you, at least with any even remotely "normal" household load.

author: Jeroen3
author_rank: Super Contributor
timestamp: September 24, 2024, 06:15:02 am
content: You mean there is some error in the accumulator choosing which counter is active?I don't think that is that much of a problem. The integration time should be fixed, and the totals at the end of this time are added to the active tariff depending on the direction of energy. Should not have error.(or at least, it's within the class of the meter)

author: Someone
author_rank: Super Contributor
timestamp: September 24, 2024, 07:57:26 am
content: Quote from: Siwastaja on September 24, 2024, 05:35:16 amGiven most of the tariffs in Australia price incoming and outgoing energy at significantly different rates I'm confident they use the import and export registers directly. This is evidenced by Daves data where import and export are explicitly called out in each 30min period and can both be > 0 in the same period down to tiny accumulations.Example meter that aggregates a 3 phase supply to the simple data ready for billing:https://mercs.com.au/wp-content/uploads/2019/12/20181707_ME-PM-M4-5-PROTOCOL.pdfCode:Reg 38 Import Wh since last resetReg 39 Export Wh since last reset

author: Jeroen3
author_rank: Super Contributor
timestamp: September 24, 2024, 09:06:10 am
content: I wonder how fast the power oscillations need to be for the meter to start missing them.

author: Siwastaja
author_rank: Super Contributor
timestamp: September 24, 2024, 09:44:17 am
content: Quote from: Someone on September 24, 2024, 07:57:26 amOK, which would mean there is no so called "net metering" at all, or in other words, any netting is down to the time resolution internally used by the meter for sampling, so very short. Possibly there can be import and export even within the same AC cycle. Would you agree?Some years ago I was still under no-netting billing and when the hourly netting was finally mandated by law, the last few reluctant grid companies (such asmine) switched. The difference in bill is quite significant and while I understand the reluctance of going to very long netting periods (allowing people to use the grid like a battery in billing sense), something more than milliseconds would be fair but I guess unless it's mandated by law then there is no incentive for power/grid companies to do that.This is only important when the import and export prices are significantly different, as they often are, and as, IMHO, they also should be. Paying the same price for exports would be a significant hidden subsidy of a kind. I would rather see net metering + fair prices than no net metering + artificially high export price.

author: Someone
author_rank: Super Contributor
timestamp: September 24, 2024, 10:57:12 am
content: Quote from: Siwastaja on September 24, 2024, 09:44:17 amI dislike the term net metering so glad you "quoted" it. Agree that timescale between swapping which accumulator is incrementing may be incredibly short as that is to the benefit of the retailer. It would need some hunting through technical data sheets to find out exactly what (programmable range?) it is set at.

author: Siwastaja
author_rank: Super Contributor
timestamp: September 24, 2024, 12:20:34 pm
content: Quote from: Someone on September 24, 2024, 10:57:12 amI think while the concept is valid, people carelessly add expectations of some particular netting period on the term itself. For example, even Wikipedia has adefinitionwhich veers off to some certain measurement periods:Quote from: https://en.wikipedia.org/wiki/Net_meteringProblematic parts emphasized. I mean it's never "anytime". Even if you have the best of the best, annual netting, you won't be able to generate a lot this summer and use it five years from now. And then this quote kinda implies it has to be in the timescale of at least a month to be net metering. Why don't they, for completeness, mention an example of 1 second, why wouldn't that be net metering?And here "net metering" is used to mean "use within 15 minutes". And in the end, all metering is net metering, so the whole binary discussion of whether one has net metering or not is kinda flawed. Maybe someone has net metering with period of 0.5 milliseconds, as accumulated into the two registers by a certain meter implementation. But it isalwaysthere, simply due to laws of physics it has to be, there is no physical concept of simultaneous export and import on a wire within same instant moment.So I'd prefer to see the number instead of binary yes-no label, then it would be simple to compare the options, because (assuming export and import prices differ) then it's a simple "bigger is better" feature. I made some calculations when transitioned to hourly net from "no netting" (so some millisecond netting) and that increased my PV self use % from 52% to 70%, during the same time frame (calculated using both ways from the same data, both were available from the grid company). Then this also boils down to the question of how you define "PV self use". It has to be associated with some time period as well.Here a few years ago some companies offered contracts which basically implemented yearly net metering and called them "virtual batteries", but they quickly fell out of fashion. Quite obviously such business cannot be a charity, so average customer of theirs must lose money. Basically what they did is to pay extra for exported energy to match the import price, and then get the same money (+more) back with monthly fees. And of course it comes with complex set of extra terms and conditions. Totally wasted human effort.But, some netting period in range of, say, 10 seconds to 1 hour or so, would be fair to all participants including energy producers, grid operators and customers. Excessively short periods generate all sorts of weird issues with dynamic response of systems, e.g. Dave's issuescouldbe related to too short net period (could be something else too of course). And it's nearly an anti-subsidy that you need to constantly import and export (e.g. when your thermostat is working on/off) while things in grid average out - your neighbor's thermostat isn't in sync with yours, so the burden you are placing for the whole grid and whole existing generation infrastructure does follow some longer than a few seconds average of your net power.And then again excessively long periods are unsustainable for whoever is paying; it's a hidden subsidy paid to PV owners. Say 24h netting period: now you are getting bargain electricity at the most expensive hours possibly with shortage of production just because you produced 7 hours earlier when nobody really needed your energy. It obviously gets even worse with annual netting.

author: Jeroen3
author_rank: Super Contributor
timestamp: September 24, 2024, 01:08:20 pm
content: Net metering is an invoice things. The meter itselfshouldnot be a part in that.What you mean is how exact the meter can replicate the Ferraris energy measurement method.I found a manual of alandis gyr e350saying the "measurement time" depends on the current and is somewhere between 20 and 70 seconds. To maintain accuracy in low current the time is longer. Makes technical sense to me. But it has implications.It is interesting, does this mean that you could net 0 within this time, no counters change?I have written DSP for power measurement, but not for energy.

author: coppice
author_rank: Super Contributor
timestamp: September 24, 2024, 01:24:36 pm
content: Quote from: Jeroen3 on September 24, 2024, 01:08:20 pmMany meters only collect the net energy. Recent ones are tending to use separate import and export bins, to make things like solar installations integrate more smoothly, but there is a huge installed base of meters which only collect a single net energy bin.

author: coppice
author_rank: Super Contributor
timestamp: September 24, 2024, 01:39:43 pm
content: Quote from: Monkeh on September 22, 2024, 06:22:15 pmI think if you do an internet search you will find multiple studies which have seen very big errors in the measurement of utility meters with difficult loads. Enough of them from institutions that seem to show something bad is going on. What is missing is enough follow up material to identify what is going wrong in those meters. Well, from having worked in this area I can give two educated guesses:The specifications and approvals tests are weak on what happens with loads with a wide harmonic spectrum. If the meter is, say, a 60A maximum one, they want a 60A current signal to exercise the ADC's input range well. However, if they take the sine wave maximum too close to the full range of the ADC they have little headroom for the crest factor of a distorted waveform. You'd think there would be at least a little bit of specification and approval testing in this area, but there isn't. Its quite possible that substantial errors come from the ADCs clipping.The meters I have seen which use Rogowski coils digitise the output of the coil, and do the calculus digitally. This is a problem when the waveform is spiky, as the output voltage is proportional to the rate of change of the current being measured. The peak output of the coil can be huge under those circumstances, and will clip hard at the ADC. This is like the first point on steroids, and in the reported testing the really big errors seem to be with Rogowski coil based meters..

author: Jeroen3
author_rank: Super Contributor
timestamp: September 24, 2024, 02:18:01 pm
content: Yes.https://ris.utwente.nl/ws/portalfiles/portal/276415600/2021_EMC_Europe_Static_Energy_Meters_Running_Backwards.pdfI can imagine creating such, "quadrant errors", with incorrectly tuned digital filtering that adds unintended phase shift with those poor current waveforms.But they never looked into it further I believe.I don't think domestic meters use Rogowski coils, I believe most of them are shunt based.As these are the most accurate and not easily influenced by external fields. But I could be wrong.

author: coppice
author_rank: Super Contributor
timestamp: September 24, 2024, 02:36:56 pm
content: Quote from: Jeroen3 on September 24, 2024, 02:18:01 pmVery wrong. There are millions of Rogowski coil domestic meters, especially in the US, where split phase power means a simple shunt sensor doesn't cut it. The thing that has held Rogowski coils back is they are HIGHLY influenced by external fields. Considerable research has gone into designing coils where the external influences cancel out across all the turns of the coil, but they are far from perfect. I have seen piles and piles of attempts to build immune coils within multi-layer PCBs, because there is a British company (whose name escapes me) that specialises in doing this which inspires them. Most people abandon the work in failure. Its a problem.

author: Siwastaja
author_rank: Super Contributor
timestamp: September 24, 2024, 02:47:22 pm
content: Note though that all reported incidents of serious accuracy problems that I can find are from very unusual (I mean it in the sense of: either unintended, or malicious) loads. Like the water pump example discussed on this forum, and the above "let's use a triac dimmer to supply short 30-amp pulses to off-the-shelf SMPS". Such loads are either illegally on the market (probably the water pump), or the products are used against their user manuals (e.g. triac dimmer manuals normally list types of loads they can be used with). But in latter case the customer did not really understand they were operating a triac dimmer. So it will be hard to say who is to blame.In ideal world, the meters should not misbehave even with such unintended loads, but as long as standards do not specify clear test requirements, nothing's going to change.

author: coppice
author_rank: Super Contributor
timestamp: September 24, 2024, 03:07:22 pm
content: Quote from: Siwastaja on September 24, 2024, 02:47:22 pmThat pump example was a very odd one. I wouldn't focus too much on that. I think it represents more of an interesting puzzle than a broad problem. Some fairly large studies seem to have observed very poor accuracy with some common place loads. A huge number of things, even products with PFC, present a horrible mix of harmonics to the grid.

author: Electrodynamic
author_rank: Regular Contributor
timestamp: September 24, 2024, 05:27:44 pm
content: SiwastajaQuoteThere is no such thing as an "ideal world" and reality gets messy.For example, the smart meter shown below was designed and built by competent professionals following all the applicable standards and regulations. It is a marvel of modern technology which just so happened to burst into flames almost taking the house it was attached to with it. Were not sure why the smart meter had a melt down but we can say as a fact it did. I'm not implying smart meters are unsafe only that we do not live in an ideal world and stuff happens.QuoteI used to do a lot of R&D with transient effects and any time we have abrupt switching, a large inductance and small capacitance were asking for trouble. The reasons why this happens are known and are usually a result of localized LC coupling causing transient effects. So a water pump start switch partially sticks due to pitting or carbon build up, starts acting like a spark gap coupling one or more windings to the start or run cap. Now we have a LC oscillator generating HV HF oscillations within the system.What many fail to understand is that it only takes one HV impulse in a local system to break down or degrade a component. Transistors or mosfets can keep working but we get leakage, variation of a threshold/negative resistance or abnormal fast or slow switching. In capacitors the dielectric can be damaged and can act like a resistance or continually break down abruptly at a different voltage.So much of my testing was not under ideal conditions but to find the worst case scenario and it's really easy to find.

author: coppice
author_rank: Super Contributor
timestamp: September 24, 2024, 05:53:38 pm
content: Quote from: Electrodynamic on September 24, 2024, 05:27:44 pmI think its clear why there was a suddenly spate of e-meter fires, although I have no idea why any specific incident happened. If you are going to run a program of rapid meter replacements, you are going to have a lot of people doing the work who don't have a lot of experience, and probably a lot who don't have the sense of commitment wanting to sustain a reasonable reputation until retirement brings. So, you are going to see a lot of sloppy poor quality connexions which will overheat. Its inevitable in the real world. Massive demand surges in any job activity bring these kinds of problem.I expect there are also some lousy designs which were either inherently a bit weak on contact quality or cooling, or made forming nice clean connexions during installation unreasonably hard, exacerbating the problem with inexperienced fitters. There is a big difference between getting pristine samples through approvals tests, and mass production and deployment.

author: Siwastaja
author_rank: Super Contributor
timestamp: September 24, 2024, 06:30:56 pm
content: I would agree the most probable explanation for the fire is incorrect wiring: insulation getting under screw terminal, wrong torque, completely loose screw (I have seen that happen, like, the sparky just pushes the wire in thinking "I'll tighten the screw later" then forgets about it). But can, of course, be a mistake in meter design or manufacturing quality control.

author: coppice
author_rank: Super Contributor
timestamp: September 24, 2024, 07:02:58 pm
content: Quote from: Siwastaja on September 24, 2024, 06:30:56 pmI expect a lot of people who never wired anything bigger than a kettle have been doing these installs, and not really grasping the huge difference between what you can get away with in a low duty 10A circuit, and the connection quality you need for a stable 60A or 100A circuit that might run at high load for hours.

author: tszaboo
author_rank: Super Contributor
timestamp: September 24, 2024, 09:28:26 pm
content: Quote from: coppice on September 24, 2024, 02:36:56 pmEU directives have made shunt based meters outdated, because they were inefficient. The meters were adding a bit of consumption, but if you add that together for 100 Million homes, it's a lot. So they are not going to install new meters with shunts.The EDMI smart meters will be Current transformer based. At least all of them that I've seen were like that.

author: coppice
author_rank: Super Contributor
timestamp: September 24, 2024, 09:57:26 pm
content: Quote from: tszaboo on September 24, 2024, 09:28:26 pmThe last time I looked they didn't ban shunts. They just set consumption limits for the whole meter and the sensor. If you use a 150 micro-ohm shunt, at 60A the shunt is only consuming 0.54W, and the average consumption is much lower. The guts of the meter is consuming all the time, and these days those guts have got quite complex. How much is the typical EU smart meter now consuming continuously, with all they have forced into them?

author: Someone
author_rank: Super Contributor
timestamp: September 25, 2024, 02:18:12 am
content: Quote from: Siwastaja on September 24, 2024, 12:20:34 pmNet weight: the weight of the underlying part contrasted with gross weight the sum of the whole.Net price: inclusive of costs, taxes, discounts etcSome places used "net metering" as in net weight, 100% of solar sold out at the export price, 100% of consumption bought at import price. Zero self consumption behind the meter, all energy accounted for through the market pricing. Which is a dumb way to meter but it adds massive confusion when using the "net" term as they meancompletelythe opposite in the two uses.

author: Jeroen3
author_rank: Super Contributor
timestamp: September 25, 2024, 06:12:40 am
content: Quote from: tszaboo on September 24, 2024, 09:28:26 pmThat's odd. I know from someone developing meters it's very hard to get the accuracy requirements at low load with CT's.I also don't think a CT is lower resistance than a copper bar as shunt.But maybe EU meters are different from US based.50470-3:2006 has a table with as low as 2.5VA for class A meters or 1 VA for transformer meters.And 2 W/ 10 VA for the voltage circuit. Did they make this even lower?

author: nali
author_rank: Frequent Contributor
timestamp: September 25, 2024, 08:50:14 am
content: EDMI use both shunts & CTs across the range. A problem with shunts is self-heating and maintaining accuracy across the environmental range, they also do suffer a bit from external magnetic fields as the busbar/shunt + Kelvin connections make a loop which has to be nulled by counter-looping the PCB tracking. The objection to CTs is probably cost.

author: tszaboo
author_rank: Super Contributor
timestamp: September 25, 2024, 09:12:44 am
content: Quote from: coppice on September 24, 2024, 09:57:26 pmI don't have the numbers or the EU directive in front of me, but a quick search suggests that the limit is 0.6W per smart meter, which seems reasonable, even though they could've gone lower. So you will hardly pass that requirements with shunts and 3 phase systems. And no, they didn't ban shunts, they just made it very difficult to achieve the legal requirements with shunts.

author: IanJ
author_rank: Unknown
timestamp: September 25, 2024, 09:49:05 am
content: All,In my system I am reading import and export power, but not from my EDMI Smart Meter, I fitted my own Owen Brothers modbus capable OB418 meter.As I have stated before I also notice a residual import wattage when solar is making more than enough to power the house.......it varies between 1W and 20W, sometimes it is 0W.Here's the spec, which may offer some insight as the EDMI Smart Meters are probably something similar:From the OB418 manual:-lref = 10A-ltr = 1A-lmax = 100A-lmin = 0.5A-lst = 40mANot from the manual, I believe this is the terms:Iref (Reference current) = 10A: This is the reference current used for calibration. It’s typically the current at which the meter operates with its highest accuracy.Itr (Transition current) = 1A: This is the current at which the meter transitions from low-current measurement mode to normal current mode. It’s a threshold below which the meter might use a different mechanism or mode for accurate measurement.Imax (Maximum current) = 100A: This is the maximum current that the meter can safely handle and measure without damage or loss of accuracy.Imin (Minimum current) = 0.5A: This is the minimum current that the meter can reliably measure. Below this current, the meter may not give accurate readings.Ist (Starting current) = 40mA: This is the starting current, which is the lowest current the meter can detect and start measuring.Ian.

author: uer166
author_rank: Super Contributor
timestamp: September 25, 2024, 05:46:52 pm
content: Transition current has absolutely nothing to do with internal meter "modes", it's only a meter accuracy term.