question

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AC2 Load Shifting (Dump Load) on Multi with ESS

I designed an external load-shifting (dump load) circuit on a previous install with a lithium battery (SolarMD 7.4kWh) and a Voltronics 5kVA inverter which the battery Data Logger was able to see and control. This setup allowed me to use SOC to close the relay and PV Input level to open the relay. I decided to shift to Victron for a more robust system. My current setup has a Multiplus 5KVA connected to a CerboGX and the battery Data logger also connects to the CerboGX (allows for the Battery BMS to control how the 250/100 SmartSolar charges the battery). I have 10 x 430W Longi mono PV array which peaks out 5,300W on good day and average about 4,500W.

blueboard.jpg

I have ESS enabled for self consumption with battery life priority (Grid kicks in if battery reaches 20% SOC. I have nothing on the AC2 out and hence this post. It seems Victron supports dumpload on AC2 and I have read the various experiences on programming the relay to this effect.

My current setup utilises an external circuit of two latched Contactors (C1 & C2) configured as follows:

contactors.jpg

  • C1 is activated by connection of its coil to the Datalogger NC
  • C1 closes the Grid supply through it to Geyser and AC MCBs as well as the neutral lines to the Grid Neutral bar
  • C2 is activated by connection of the coil to the Datalogger NO
  • C2 when activated Inverter (A1) line to the Geyser/AC MCBs as well as the neutral line to the Inverter neutral bar
  • C1 and C2 can not activate at the same time. Its either/or

Relay CLOSE

  • Time: 10:30-14:30hrs
  • Day: Mon-Sun (Daily)
  • Delay: 5min
  • Logic: IF SOC% >98%

Relay OPEN

  • Time: 13:00-17:00hrs
  • Day: Mon-Sun (Daily)
  • Delay: 5min
  • Logic: IF SOC% <95% (I can not use PV output level as the Logger doesn't read MPPT output)

Question

It seems less fussy to utilise the Multi 50A changeover and outputs to control seeing that AC2 could be connected to my none critical loads as I've read and programmed in similar manner as above, is it then possible to independently control AC2 in the presence of Grid to supply Grid power to the loads say at night when I switch on the geyser? Can AC2 be controlled separately from AC1 in ESS? I ask because the setup would require that AC2 allows Grid through at night whilst on AC1 there is self consumption being prioritised.

MPPT - Solar Charge Controller
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1 Answer
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kalito answered ·

@Daniël Boekel (Victron Energy Staff) your explanation on the history of AC2 out here: https://community.victronenergy.com/comments/73020/view.html

seems to have answered the above. AC2 is merely an AC1 but with breaker which activates by default when AC in is lost unless programmed otherwise. It can not therefore be dedicatedly isolated.

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