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Solar PV diversion with priority to immersion, sockets and EV

openevse
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(Colm O'Brien) #1

Hi all,

I’m a newbie and apologise if this question has been asked/answered before. How feasible is it to divert excess solar to an immersion or specified sockets with a specified priority up to certain threshold but over that threshold a specified amount or all of the excess is used to charge an EV?

Many thanks,
Colm


(stuart) #2

It depends upon how much solar you have - most EV’s need at least 2KW (think about 8A) minimum to keep charging so you need a good sized solar array to even make it worthwhile - particularly in winter.

The immersion divert is easy enough, there are plenty of commercial units and this site has instructions on DIY solutions.


(Peter Galbavy) #3

Just to clarify, the minimum EV charge current is 6A in J1772 (what you car will use, regardless of connector). The voltage is localised so you can, if you want, supply 6A at 110V (or less) but in the UK with the typical 240V this means you need 1440W minimum. More info https://en.wikipedia.org/wiki/SAE_J1772 - see the Signalling section.

In terms of the rest anything is possible - I use node-red to alter the advertised current to my EV - but you need to think about ensuring that whatever you turn on can stay on for some useful minimum period and not to thrash anything on/off too much. I use pairs of node-red triggers to wait for a minimum level for N minutes before triggering a relay to enable the EVSE and a similar pair to wait M minutes before turning it off again if the spare power falls below a chosen current.

Note: I am talking about my own emoncms/RPi implementation controlling an ABL Sursum EVCC, and not the OpenEVSE!