OpenEnergyMonitor Community

PV and night tariff + EV and immersion heater

Tags: #<Tag:0x00007f1bd6ea1840> #<Tag:0x00007f1bd6ea1750>

Hi all!

I have installed many Zappis and and some Eddis made by MyEnergi, but I wanted something open source to play with for my own house. I am looking for an open source solution to use spare solar and integrate battery storage system in the future.

From spare solar:

  1. charge the car
  2. when there is not enough spare energy for car charging, divert spare power to run immersion heater.

At night time when electricity is cheap and car battery is empty (like Octapus GO) I would like to charge the car (probably all winter). Or when there is even cheaper electricity available (like Octopus Agile) - charge the car and heat hot water (I am on Octopus Go and havent tried Agile tariff).

Few years ago I bought “OpenEVSE WiFi Emoncms EV Charging Station” (still sitting in the box) and I was thinking to add “emonPi Energy Monitor - Solar PV Bundle” (from reading it looks like it would work to charge the car from spare solar).
But I am not sure how to deal with hot water. Can a budget option like Solic 200 be used for this? I have been reading about “MK2 router” - would that do the job?


Robin’s Mk2PVRouter is designed to be completely stand-alone. Depending on where you measure the grid current (it attempts to balance that at the place it’s measured to zero when there’s surplus PV being exported), it can ‘mop up’ surplus PV after the other devices have had priority, or probably it can have priority over the other devices, if those see it as part of the “house load”.

Of course, the big advantage over a commercial unit is you can rewrite the software to suit your needs, or you can substitute a (purchased) proportional controller for the “burst mode” triac that is part of his standard kit.

Reading between the lines, it seems that you will want water heating timed on and most likely when PV is not available - the override input on Robin’s diverter would give you full power when enabled, and normal operation when not.

You can email Robin at his address on his website, he’s quite happy to discuss special requirements.