I’ve been running Robin’s diverter on an emontx v2 for many years now. Its only recently that I finally moved over to a Smart meter. So its the first time I can compare what the emoncms Solar divert app is reporting as opposed to the IHD. Both are updating in 10secs.
My IDH seems to almost always be about 50-60W more than what emoncms reports. So even when emoncms says Perfect Balance, the IHD will show an import of about 50W. Infact the IHD is almost always off by 50W.
Now that could be because my CT reporting parameters arent tuned to match the meter well enough and its the first time I can see the meter’s data itself in near real time.
However how can I be sure than the divertor isn’t actually importing electricity when it shouldn’t.
There is a comment in the code that suggests that the various adjustable parameters in the code dont affect the diverter’s functionality but are more there for accurate reporting.
Now I am paranoid that instead of me being clever, I’ve actually been pulling electricity to heat the water!
You’ll probably find that the smart meter’s “energy bucket” (in Robin’s terminology) is significantly smaller that that of your old Ferraris meter and the diverter’s, and this is what’s leading to an import. You probably need to read up on Robin’s site (the UK one, because he’s transferred the business to a couple in France, he now supplies only a limited range of spares) because he had a lot of success with French smart meters and his latest sketches were tailored for that market. You’ll obviously need to do some work to move from his PCB back to the emonTx V2, but this should be relatively straightforward.
You’ll need to consider flicker when you change things. Each sketch is accompanied by a text file with some explanation (“About” next to the download link on the Downloads page).
Robin still visits here moderately frequently so he’ll probably see this within a few days, but he’s busy with some civil engineering in his garden today.
When I installed a pulse meter it was clear to me that my emonTX3 was not that accurate. I ended up putting a scaling factor of 0.9438 in the input processing and it is now very accurate.
With scaling factor emonTX v Pulse over 2 weeks (1 kWh diff)
emontx raw v scaled (13.3 kWh diff)
The key question is really if you are seeing power flow via the CT in emoncms.
If my IHD is reporting a 50W import then I have to assume that an import is taking place.
If just the reported values are slightly off, I’m not too fussed.
What I am not sure about is what do I need to change within the sketch to adjust the Energy Bucket so that I would rather be Exporting than importing.
I assume nothing Might be the minimum unit that can be displayed rounded up (will not round down) from 1W.
What does the CT value say?