A few Pre Purchase Questions

Hi Chaps

hopefully some not too stupid opening questions before I decide whether to purchase

the EmonPi and EmonBase, do they use the Pi3 or Pi4? If currently the Pi3 is there any reason a Pi4 couldn’t be used for the EmonBase? I ask as I see the EmonPi is currently out of stock so starting with an EmonBase is likely to be the plan. I’m familiar enough with the Pi that the lack of display doesn’t concern me.

My day 1 use case will include Solar PV monitoring. As I have a Bluetooth Sunny Boy invertor that currently works fine with Oxley Solar I believe I can simply connect to it using bluetooth and the inbuilt code written by Stuart?

I’m assuming this would be the best option as you can see more details on what’s generated by each string, as opposed to the clip on units which would just give total inverter output?

I note that multiple EmonTX units can be added but that its advised not to go overboard due to congestion on the 433mhz RF data connectivity.

Further to that I see there’s an option to connect a wifi board to the EmonTX and connect to the Emonbase that way. Would this alleviate the bottlenecks?

I further see a mention here System Overview - Guide | OpenEnergyMonitor that

Both the emonPi and emonTx + emonBase systems support WiFi and Ethernet provided by the RaspberryPi. To use Ethernet with the emonPi, ethernet is required at the metering location. The emonTx + emonBase configuration allows for separation of the metering location and the base station which can be located next to your internet router.

Since theres seems to be an ethernet port on the EmonTX should I read that as the EmonBase and EmonTX can communicate hardwired on Ethernet rather than 433mhx radio or wifi?

I can easily get Cat5 where needed and generally prefer hardwiring as its the least troublesome.

And finally, the extra board supplied with the EmonBase, is this just the 433mhx carrier board? If so and wifi or Ethernet is used for connectivity between the EmonBase and EmonTX, would that allow the possibility to run the EmonCMS software on any pi and mean I don’t specifically need to buy the EmonBase?

thanks in advance


The EmonBase is a Pi + an RFM69Pi board. If you have a Pi 2/3/4 you’ll only need the RFM69Pi.

It’s been a while since I connected to Sunny Boy inverter directly (using the RS423 adapter add-on in the inverter + an RS423/usb serial adapter) but it wasn’t great, it worked (wrote a whole pile of Perl to interpret the data), but the data was soooo slooooow, as to be useless for doing anything useful with it.
So I switched to CT’s and an EmonTX to do 10sec sampling.

I have two now and bunch of DIY EmonTH units, and there’s an occasional clash but it works great.

It would, but I’ve not used that.

There’s no ethernet port on the EmonTX, there is an RJ11 port that’s used for DS1820 temperature sensors.

Yes, that’s the RFM69Pi as mentioned above, it’s a low power radio transmitter/receiver to pick up data packets from EmonTX/TH/etc.