Advice on monitoring house with solar PV and battery storage

Hi there. I have a newly installed Solar PV system with battery storage

  • 20 x 380W panels feeding into a Growatt 6kW inverter
  • PureDrive PuresStorage II 10kW AC-connected battery

The battery comes with a monitoring app but the data is only accessible through a PureDrive cloud app and that isn’t always online. It also doesn’t let me monitor the house electrical load. What I would like to be able to do is monitor / keep a record of:

  • grid import, grid export
  • battery charge, battery discharge
  • solar generation
  • house load
  • power factor (if possible)

I looked at the Solar PV application on this website but the battery storage appears to make things more complicated. I would appreciate advice on whether this is doable with the openmonitor family?

In case it helps, I’ve attached a simplifed diagram of my setup. (The CTs denote where I think I would need to put the current transformers.)

Hi, welcome.

Yes that looks about right. You’d need to do some processing on the emoncms Inputs as per your summary, but other wise I think it will work.

You’d need a TX4 & emonVS for the measurement. You can record the data on emoncms by either using an emonbase or if you have another server install emoncms on that.

If using an emonbase, if you can, place it near the TX4, connect in by USB or else it will communicate via RF. If using your own server get the Wi-Fi module for the TX4.

This is pretty much my setup, except that I have a Tesla gateway where your brown bar is, with solar and battery connecting there.

The sign of the data inputs from the CTs can be used in the feed processing to calculate useful additional feeds. For example, separate logging of the battery to charge/discharge w and cumulative kWh feeds.
EmonTx4 with EmonVS is pretty accurate, but you may need to use processing steps or calibration to get alignment with your battery and inverter app data (assuming you want to duplicate them, rather than believe the CT readings!). I had small offsets to apply, but that is probably because I use the EmonTx4 for temperature monitoring too. Until a recent firmware update, this did have some impact on CT readings.

I have cobbled together an EmonCMS display that updates the Solar app. This doesn’t carry across to the iOS app, unfortunately. I just use the existing solar app and dashboards, which suits me. I’d probably learn to code it properly if I was younger!

Thank you @borpin

Looks like I’m going for a TX4, emonVS and emonbase. I’ve got space to install them next to each other and there is ethernet in my boiler / power room too.

I’ve found some useful threads here on how to process inputs to separate import and export values. Thanks again.

Thank you @AndyS

That’s reassuring. I’ll be interested to see how the measurements stack up when the kit arrives.

I’m not completely confident in the values reported by my current battery / inverter app - it consistently reports lower values than the smart meter (5-15% lower, average 10% lower) for grid import.

I haven’t yet resorted to plugging in 3kW resistive loads for calibration … yet.

Thanks again.

I recall there was an issue with a particular smart meter being wrong when used with a Tesla. Resolved phantom drain Tesla Powerwall 2 and Landis+Gyr E470 smart meter - YouTube is what I can find, but there is a fair bit of chat on the Tesla forum about this too. I have no issues with OEM/EmonCMS values versus the smart meter, or versus the inverter and Tesla apps.

I find the OEM displays really helpful when trying to work out what is going on with power flows in our system: it is the only data that sees everything in near real time. At present, the ability (desire?) of the various manufacturers to make data on their systems “open” to inspection is pretty poor. Case where regulators really ought to be active, perhaps?

Thanks. Interesting story and diagnosis of the problem on the Octopus web site.

When I get the emon stuff set up, I’ll be able to compare and contrast the readings of: PureDrive OEM app, Aclara smart meter and emonTX. And there’s always a manual meter if necessary.

Sadly the Puredrive battery system appears to be closed with hardly any information about it on the internet. If you want to schedule your battery to charge from the grid at specific times, you have to call and ask Puredrive to connect to your battery to make adjustments. And its OEM display is a blue light.

The other way to deal with the electric import/export is to get one of the Glow IHDs as I believe it will give you the import/export figures.

I’ve got one and it works really well :slight_smile:

I can see that the Glow IHD could be a convenient way of extracting data from my smart meters and sending it to a local server.

I already use the Bright app and to get 30 minute data but haven’t been able to work out how to get Glow to recognise my export MPAN and read data from the export meter. Periods of export are just shown as zero consumption.

I suspect it is the type of meter. My ‘smart’ meter generates a JSON Output that includes an export component so I would expect if I ever exported that would get populated. Note the Glow IHD is distinct from the online system as it is reading from the meters directly on the LAN and not just getting the data transmitted by the meter over the WAN.

It is an assumption though.