Using energy monitoring on a large wired site

I am a new user of Energy Monitor and have read most of the site. The closest thing I have found that discusses an answer to my problem is Martin Roberts plan of Solar PV Power Diversion with emonTx Using a PLL, emonGLCD and Temperature Measurement. (
However this will not work for me as the Solar Power generation connection to my local power network is 75 yards from the place where my power network is connected to the grid. Also we dont like wifi or radio waves we believe it is harmful to humans so we have an installed an extensive LAN to provide internet access.
Surely the long term general solution is a box (probably a Emon Pi or tx) near the grid connection, a second similar box where the power generation connects to the local power network and a third box near any diverted load to deal with excess power. This last one should also support a battery rather than just hot water.
This would support a general solution to the generation of Solar energy and reducing power consumption from the grid. Martin’s solution is good but does not allow for adequate local communication where the supply, PV generation and load (preferably battery) are physically distant and radio/wifi is ruled out.
Any solutions?
Gordon Webb

Welcome, Gordon, to the OEM forum.

Your potential problem with a network-based solution may well be delays between measuring the power and acting on the data. Both MartinR’s and Robin’s diverters react within two cycles to a change in conditions, a delay could lead to the system ‘hunting’. The link between the “decision-maker” and the power switch could well be hard-wired using a telephone-type cable - ‘pulse’ (in the diagram) is the drive current for a LED so cable resistance could be compensated by reducing the value of the current-limiting resistor. That would eliminate one possible source of delay.

If you’re looking to charge batteries from the surplus generation, you probably need an analogue solution rather than burst mode (unless you can control the charger in burst mode, as it’s unlikely to be happy if it receives chopped up mains).

If you do go for a commercial battery solution, there are a couple of threads about using that with one of those diverters: there have been stability problems because it would appear that the installer didn’t know about or didn’t understand how the two systems might interact, and it ended up with each trying to optimise the other.