2 years ago I used arduino uno to monitor solar generation to charge my battery car only when sufficient generation available with touch screen displays and to input options. This has worked extremely well within the measuring limitations.

I now wish to vary the charging power by monitoring export power and so keep export power to a hundred watts.
My solar I-boost water heater does this quite well, one thought was can the wireless signal between its CT and controller be hacked into and shared?

Any suggestions as to how to monitor export power would be appreciated.

Thanks.

Hello, I am wanting to display MPG on an old VW camper van. Does anybody know of a hall effect flow sensor that can report the very low flows found in carburetors please. Alternative suggestions always welcome.

@gohan Thanks, eventually worked it out. https://pastebin.com/D0Cc8TSG should do it for you. writing to the Nextion is creating difficulties.

Hello Gohan, unable to find the paste bin or any help section. I need more precise guidance please.

@gohan Sorry I have been so long, some things, apparently, are more important than playing on my laptop. I managed to lose the "saved" copy when looking at Nextion mods. I have recovered/repaired and tidied the code but I need your help as to how to share with you.

@zboblamont I cannot see any sockets for a digital o/p. Neither is a smart meter, but both are only 2 years old. The grid meter has an additional green led when power is going out of the house.

@shabba I have used a clamp meter and arduino uno to monitor power levels, disadvantages are that you need to full wave rectify, provide load resistor and smoothing. Measurement becomes a bit of guesswork as to how many volts o/p in a Kwh.
Here in Britain, meters have a LED that flashes 1000 times per Kw. I have used a digital light sensor input into arduino uno digital input and then measured the time between flashes in msecs to give accurate readings. I use have used both methods to monitor solar panel output, then turn on Leaf BEV car when sufficient free power is available and off again when clouds arrive. Next step is to o/p readings to a Nextion for both solar and grid power readings with adjustment of turn on thresholds to optimise summer and winter useage.