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Forum Index : Electronics : Sig Energy Topic
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| mab1 Senior Member  Joined: 10/02/2015 Location: United KingdomPosts: 280 |
If Sig doesn't have a zero offset tweak facility, you could 'hack' it by threading a thin wire through the Sig CT (i assume it uses a CT on the meter tail), and use a low voltage transformer and resistor to pass 10W worth of a.c. through the CT (42mA?) to make it 'think' you were importing another 10w. |
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wiseguy Guru  Joined: 21/06/2018 Location: AustraliaPosts: 1281 |
Thanks Mab, that is so devious - I love it. I have used that technique with DC sensors (using DC) with no tweak adjustments for similar offset reasons. My system is 3 phase so it gets complicated quickly but I know there are small 415V transformers available usually for delta connection but if I use them for star they will have naf all idling current and still easily supply what I need for such a tweak. I'm embarrassed to say I have no idea about the installation and have never removed any covers. There was a time where I often pulled covers etc off something to see what made it tick before I even used it, I was probably a little worried about Sig warranty issues too. I know they have remotely looked at my system, what if they notice my fix and "helpfully" tweak it back to zero remotely for me lol. I am contemplating doing this at least for a short-term fix. I will guess the CT's are in the gateway box as the system needs to automatically isolate the grid from the house if the grid goes down and that gateway box is full of contactors - so where's my screwdriver.... Edited 2026-05-03 09:09 by wiseguy If at first you dont succeed, I suggest you avoid sky diving.... Cheers Mike |
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TassyJim Guru Joined: 07/08/2011 Location: AustraliaPosts: 6515 |
Hi Mike, I read your comments with interest. My installation is only a small grid-tie but I have noticed the same difference with metering between the power authority (Aurora) and my Enphase solar control system. I access the Enphase metering via HTTP which requires a free "token" from Enphase. The token only lasts 12 months so it is an annual task to renew it. I have similar field of data to play with. The reactive power swings + and -. Unfortunately, the active power spends too long on "import". I need to remove a few more trees on the western side. I have 12 micro inverters which are only interrogated every few minutes. Not a problem if you are only after accumulated energy but not good for instantaneous power. I have my own metering CT on the heat-pump where I calculate power every 500mS. For the EV charger, I use a Lanx power meter with 2000 pulses per kWh. This works well for the steady load of the charger. I have thought about putting my own CT on the incoming mains and use the same setup as the heat-pump but accumulating power in both directions. The authorities would not be impressed with any mods on their side of things. For now I make do with the inconsistencies. I only use the information for power scheduling and trying to decide if I should increase the size of my system or change the tariff. Jim VK7JH MMedit |
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| wiseguy Guru Joined: 21/06/2018 Location: AustraliaPosts: 1281 |
Hi Jim, thanks for the post and comments. I think I misunderstood your post, I re-read it a few times so I will ask a question for clarity. I did not see the word "battery" used - I was expecting the mention of an Enphase battery, you aren't using one? It sounds like what your Enphase system is reporting and what you provider is reporting don't match and I'm guessing not in your favour. That is why you want to separately monitor your energy import/export for an independent report? The power network people do not like you doing anything to their wiring but I believe the current measuring CT's used are (split) that can be clipped to a conductor without making any wiring changes. For voltage information you can make your measuring device circuit wired with a 3 pin plug into a handy socket and then with an isolation transformer like a 2mA to 2 mA part you have phase information volts and amps calculate as desired. My understanding is that you are allowed to build something that connects to the mains with a 3 pin plug but nothing hard wired to the house wiring. You are not allowed to sell such a device without appropriate safety tests and approvals etc, but you can use it for your own purposes and the Darwin principle applies - please take care  I assume the shading issue was mentioned because of the deficiency of solar without any battery storage to carry you over the short fall dips, prime the chinsaw..... Edited 2026-05-03 23:39 by wiseguy If at first you dont succeed, I suggest you avoid sky diving.... Cheers Mike |
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| wiseguy Guru Joined: 21/06/2018 Location: AustraliaPosts: 1281 |
I received my reply from SIG (on a Sunday afternoon !) and I have to say I am totally unimpressed but not surprised, here it is; Hi Michael, Thank you for your detailed response. At this time, there are no settings available that allow the system to consistently import or export a fixed amount of power to the grid regardless of operating conditions. Grid import and export are primarily influenced by solar generation and the site’s load consumption. Additionally, the maximum grid export active power is determined by your DNSP (SAPN), as they regulate the system’s discharge to the grid. We have also performed an advanced wiring diagnosis on your system, and no abnormalities were found. To help optimize your system’s performance, we recommend updating the firmware to the latest version. Please let us know if you need any further assistance. What a load of patronising obfuscating gobbeldygook ! The sentence starting "Grid import and export.... has zero to do with my problem, what a waste of words and implying the networks control what I export (near zero...). I have deleted the rest of my original post but suffice to say I am not done with SIG yet. All their emails end with "If you need further assistance, please let us know" Maybe they meant to write "You won't get any further (or past) assistance" so let us know... Below is an excerpt from my recent reply; Quote "This is expected behavior and not a measurement fault" When the utility reports that we have imported 28.50kWH in a month but for that month the SIG system reports a total of 1.67kWH that is a measurement fault. So Mab's solution is starting to look betterer and betterer (to quote Poida). Edited 2026-05-04 09:29 by wiseguy If at first you dont succeed, I suggest you avoid sky diving.... Cheers Mike |
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| TassyJim Guru Joined: 07/08/2011 Location: AustraliaPosts: 6515 |
Hi Mike, I should have been clearer. I only have solar and no battery. At the time, I felt that I would use much of the surplus energy to charge the car. This has work out well for 4 years but now I have an EV with a much larger battery, it is time to re-calculate things. Currently Aurora give 9c/kWh feed-in but I expect that will drop again soon. The boss has allowed me to put some panels on a north facing roof and hide the batteries on a back wall out of sight. It is 30 years since I worked for the power authority but I still know how far I I allowed to go with my fiddling. The local inspector was an apprentice when I retired and he is the only employee remaining from my days. My main interest is data acquisition and control. The local provider gives me fancy charts of usage but 24 hours behind the times so no use for management. They don't provide the data in a usable form so I can't play with spreadsheets. The Enphase people do provide the raw data monthly and I can use the api they publish to get real-time data. It is when I compare the Enphase and Aurora data when I get the monthly power bill that I can see a difference. It is not enough to cause concern, just enough to get me interested. Re the trees, I have removed all that can be done with a chainsaw but there are others that are too close to infrastructure. They will need big machinery and an equally big bill. 50 metres high leaning towards the shed... Jim VK7JH MMedit |
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| Godoh Guru Joined: 26/09/2020 Location: AustraliaPosts: 646 |
Hi Jim, is your EV capable of supplying power to the home and grid? If so there would be no need for a home battery. Our car can't do V2H or V2G, so we will just stick with our fully off grid system Maybe one day but at the moment our car doesn't have to have internet connection of back to factory communication so we are happy with that. Good luck with becoming more self sufficient Pete |
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| TassyJim Guru Joined: 07/08/2011 Location: AustraliaPosts: 6515 |
It has one 10amp 240V outlet in the luggage area and I can purchase an external one to plug into the charge socket. I can pension off one of my generators. I think I will only be using it for power outages. Jim VK7JH MMedit |
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| analog8484 Senior Member Joined: 11/11/2021 Location: United StatesPosts: 197 |
This is similar to the standard energy metering in other consumer grade inverters. You can ask them to verify but it's pretty clear the inverter does not have revenue grade metering. Some inverter makers (e.g. Enphase) do offer optional revenue grade metering at a premium. The lack of revenue grade metering is often a key cause of discrepancy from the utility reports. |
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KeepIS Guru Joined: 13/10/2014 Location: AustraliaPosts: 2124 |
Good point, but even allowing for the percentage of accuracy between the two, 1.67kWH ver 25.6kWH seem way beyond that, something insidious appears to be going on here, or am I just reading to much into it? NANO:Inverter V 8.2ks - Linux AvrDude GUI script V4.1 |
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| wiseguy Guru Joined: 21/06/2018 Location: AustraliaPosts: 1281 |
Have to agree, I believe if I designed an energy metering device I could get it to 10 times more accuracy even before the first calibration takes place. I have been throwing the figures in my head. If we assume that the net metering of the Sig is behaving if we draw ~ 1kWH over the 16 hours we are not exporting, then to balance that within the 100 odd watts The Sig reports it is ~ average 16W per minute. I could buy that as it wobbles back and forth trying to balance to zero. I am thinking if I use the MAB idea and start with a forced export of ~ around 15 to 20W it might just do the trick. I did get an email from SIG last night saying my issues are being promoted from the help desk to the technical area, who knows maybe we can make more progress without resorting to a lot of work to solve someone elses problem that seems to have become my own... If at first you dont succeed, I suggest you avoid sky diving.... Cheers Mike |
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