Regulating power based on solar generation


Does anyone know of a solution for regulating power based on excess solar production? I have systems setup already to turn switches on or off which is great but my hot water cylinder has a 3kw element in it that I know will happily take any power I send to it as its a resistive load.

So what I’m looking for is a way to take my X amount of excess solar and send it to the HWC, ie I want to throttle the power going to the element so it only ever uses Solar and never pulls from the grid.

I know there are commercial systems that do this but was wondering if anyone had an emonpi based solution they knew of? I don’t know enough about electrics to be able to build the hardware myself.


Have a look at Robin Emley’s Mk 2 diverter.
Domestic water heating with excess PV energy is the purpose it was developed for.

or indeed Martin Roberts’. Both are documented in the Learn section, under “PV Diversion”.
Robin can’t sell built systems as he’s awaiting regulatory approval, but there’s nothing to stop you building your own, provided you are aware of the dangers and follow safe practices.

Aweome, thank you. Totally hadn’t found the learn section… blonde moment.