Solar Install - Do I need to change my Shelly EM clamp?

Energy
1

A quick question - I’ve got a Shelly EM doing full house electrical monitoring in Home Assistant.

I’ve had this running a few years and it works great.

I am getting solar installed - solar PV, inverter and batteries.

Do I need to ask them to change where my Shelly EM is monitoring?

Do they also fit a CT clamp to the solar PV (for monitoring PV output - or is that essentially what the inverter is doing) and then also around the feed for monitoring grid imports and exports?

Thanks

2

Depends a bit on the type inverter/battery; most of them already provide all power data in HA by TCP or serial (personally I’de make sure I could obtain that data from my PV/batt, preferably without local data only)

If that’s the case, no need to change anything; you can do the math fully in HA

3

Maybe consider to buy a P1 ?

4

Thanks - yes, there’s a modbus connection on the inverter so I can take all the data I need into Home Assistant (via the Goodwe integration).

I wasn’t sure what happens at the supplier end i.e. do I still need my Shelly EM (not that it hurts having both) or would they use a CT clamp to monitor this anyway?

5

In my Installation an Eastron SDM630 (which gets each phase current from CT clamps) was installed into the electrical cabinet to serve the inverter with grid and house data. The inverter is the RS485 master polling the Eastron for data very frequently - ca 280ms for all power related and ca 1.7s for all other measurants. I think, this is not an uncommon way…

I just installed a Waveshare RS485 TO ETH in between to sniff the data and make use of it.

This is, how it looks like:

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The good thing with such frequent data (especially power with more than 50 samples in my 15s interval) is, I keep them in a buffer, trim out the 10 highest and lowest values and average the remaining 30+ data sets by a pyscript until the final result is given to a HA template sensor. I wouldn’t get such control of data processing capabilities with a Shelly. And I have got several Shelly’s as well…

Edit: I also get PV data from my inverter over Modbus/TCP every 15s. Would love to have the processing options but it’s only 1 data set per 15s…

Edit 2: I am not using any integration for that. All Modbus requests to the Waveshare and inverter are done with pyscript. Full control. Only the registers I need and when I need them. Just saying…

Cheers!