I’ve been running a Solar PV diversion system successfully for several years now and get solar hot water from May to September with useful diverted input from April to October and diverting around 1250kW/h per year. This system is similar to others described on this site and is dependent on counting import meter flashes on a ‘dumb’ Landis & Gyr meter to determine when that meter thinks energy is being imported or exported (the flasher on this meter goes solid red on export).
My supplier wants to install a SMETS2 smart meter claiming that it will “help me save money” (a claim not backed by guarantees….), and the current model proposed by the supplier is an Aclara SGM1200. I’ve contacted the manufacturer of that meter several times to undersand how they work but have had no response. As an American corporate Hubbell systems who own the company who owns the company that makes Aclara meters appears to subscribe to the Donald J. Trump school of public relations.
As a last resort I wanted to ask here the question in the title - Any experience of Solar PV Diversion with SMETS2 smart meters an in particular the Aclara SGM1200?
If you mean solar export, then a SMETS2 electricity meter can record both import and export electricity. After a SMETS2 meter is installed, you need to contact your supplier and request an export MPAN which the supplier will obtain from your DNO.
My solar PV was installed 5 years ago. Last year, I exported 6000kW to the Grid and Octopus paid me £0.15/kW.
Its not just that as that alone would not be sufficient to answer the question of how the Aclara 1200 meter works. I can use any information though and that would be a start.
I mean diversion to hot water, not export and am asking about how the meter works so I can redesign my own diversion system for a new meter. I don’t get paid for export (or deemed export) and try to use all the energy I generate in the house.
Without information on what I am presented with locally on the proposed meter and how it works in relation to impulses per kWh I can’t redesign the system.
From what I have been able to glean from various sources, it not only depends on the manufacturer of the meter and the model/type number, but also on the eventual owner of the meter – because many if not all can be customised by the manufacturer to suit the owner’s requirements.
Not quite, the decision on how much energy to divert is based on the difference between the short term average of solar generation and household use (excluding diversion). The import meter flash staying red is just confirmation that within its 1Wh ‘bucket’ of metering (1000 flashes per kWh on the meter) it has still determined that there is no net import.
If the meter (like some Ive heard of) had a smaller “bucket” then the diversion system control loop would need to work more quickly. And if the meter didn’t have flash function or if it didn’t go red then Id have no visual clue whether or not a net import was being metered and the control loop would have no way to fine tune itself. And worse if it metered export as import… the DNOs removed most of those meters it seems following the links on the pages highlighted by Robert Wall.
When I designed this system I used a lot of information from these pages on how meters used at the time (and fitted to my house) worked. I am just wondering if there is any information out there for the Aclara 1200 smart meter. If not, or if the Aclara smart meter has such a small “bucket” that the diversion control loop needs to operate too quickly to be feasible then I can’t continue to use diversion as I do today.
Thanks for that information which is interesting background.
I am aware that the Aclara smart meters (like their dumb forerunners) can be customised - for example counting export as import by summing both registers on the front panel display or metering on reactive loads in situations where customers are expected to control the phase angle of their loads.
Ideally if I could get my hands on a meter that was configured but not installed I could test it! I haven’t seen one on ebay though.
It seems that ‘SGM1200’ refers to a range rather than a particular type; the Aclara SMETS1 meters are SGM13xx and the SMETS2 meters are SGM14xx - when our solar PV was installed, and we needed an export-capable meter, ours was changed to an SGM1411B.
Also, I use a Hildebrand Glow CAD to send real-time electricity readings (import & export) to my local emoncms system every minute via MQTT - perhaps you could use something like this to pick up the data that you need for your diverter?
Thank you for that resource! I had a sales leaflet from the manufacturer’s website for the SGM1400 but there is more data in these brochures. I read in various documents
Test Pulse output: Active and Reactive test pulse LED’s (earlier documents)
Test Pulse output: Optical LED x Imp/kwh. Configurable for kVArh (global documents)
Test Pulse output: Optical LED 1000 Imp/kWh. Configurable for kVArh (UK specific documents, e.g. E-meter-UK-1019-SGM1400single)
By comparing the following statements I think an SGM1400 is likely to give 1000Imp/kWh like my existing meter, but that its not guaranteed as it can be configured to a number ‘x’ other than 1000. I’m still none the wiser how the kWh are calculated though with the rapidly varying in/out power flow with neutral balance that is the characteristic load of the PV diversion system.
Google AI tells me an SGM1300 is SMETS 1, SGM1400 is Smets2 and “SGM1200: Represents earlier models or different regional iterations, often superseded by the 1300/1400 series in the UK.” I think it just made that up as I couldn’t find anything about an SGM1200 searching the web without AI, which is why I came here for real intelligence rather than the artificial copy :-).
All of this leads me to believe I probably wouldn’t get an ‘SGM1200’ anyway if I signed up for a smart meter.
Regarding local emoncms, I do use that (low-write 9.8.27 | 2017.12.21 has been running for 8 years on the same SD card and is still working…) but for PV diversion I have a ‘meter reader’ in the meter cupboard and a ‘diverter’ in the airing cupboard and they keep themselves in sync without going through emoncms or MQTT. Both power use and solar generation vary rapidly and I found from experience that it is best if the diverter is aware of the ‘instantaneous’ solar energy surplus.
