Thx for yr advice. For further background detail …
The PV inverter (30 kW ground mount array) is 100 metres distant from the house and incoming grid meter so I didn’t consider radio.
Two external wifi antenna have been installed giving site coverage.
I did try with ESP Huzzah modules and gave up.
Finally settled on a robust solution for each of the 4 Nodes – RPi and serial direct with a spinning HDD for both the OS & Data partitions – power bank to be added later (unlike emonTx, RPi does not reboot after a loss of power).
(Cost per Node is in excess of £100 but in the context of a large investment, justified in my view.)
This approach means that data logging will be robust - serial direct and saved at each Node location and not affected by wifi problems – the external antenna do seem to need rebooting every couple of months.
Installation has been progressive as I’ve moved up the learning curve – spent most of the summer on the pool Node and its ASHP and water temperatures. However I now have 4 Nodes running each using a standard OeM approach – hopefully, easier to maintain, get forum help, etc.
My preference is to restrict the bespoke stuff to a fifth RPi. It is hard wired to the network, is my point of contact via Dataplicity, will be a home for a data backup and can periodically ping the 4 Nodes and 2 external antenna sending an email if anything is down.
Yr suggestion for feed file naming will solve the duplicates problem – thx.
Re yr suggestion of posting via http as if it were emoncms.org – if wifi is temporarily down, data will not be posted. When wifi is restored, is the backlog of data then posted? If not then mounting the Nodes data on the fifth RPi (using SSHFS over SSH) will provide a more complete record at the fifth RPi … or am I missing something?
Assuming I can find a way of getting the feed files (phptimeseries at 10 sec intervals) from the 4 Nodes into 1 directory on the fifth RPi that emoncms can use – will it be a problem that the timestamps for each Node will not be exactly aligned?
Remembering that the objective is to use the emoncms graphing & dashboard and csv exporting capability and, in particular, to have My Solar displayed on a RPi screen located on the kitchen counter top.
Thx for yr help.