Issues with Victron System feeding into a UPS

DIY
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1

Context:

i have a small Victron System as follows:

  • Solar panels connected to a Victron MPPT
  • The Victron MPPT connected as input to a Victron Multiplus II 12v 3000
  • Grid connected as input to the Multiplus (almost always off)
  • 800 ah (total) set of batteries connected to a Victron shunt also connected to the Multiplus
  • Multiplus connected as output to a Filax 2 ATS as primary
  • Grid connected to the Filax 2 ATS as secondary
  • Filax 2 ATS connected as output to a Cyperpower UPS 1500
  • Firmware is up to date on all Victron components and the UPS

Further context:

  • The idea is to use the Victron system to power the Cyperpower UPS which in turn powers a small home lab. The idea is to power the home lab via Solar whenever possible, and I manually switch to grid (by turning off the Multiplus II Inverter when the battery gets low).

  • The Victron System Frequency is set to 60Hz. However, I have read when it operates it outputs 61 Hz to instruct the PV inverter to provide 100% of available power, while 62 Hz instructs it to throttle down to 0%.

The problem is …

At times the UPS will go in and out of battery draw mode multiple times for 3 or 4 seconds each time. I’ve notice that this happens when the battery is at or near 100%, however it has happened when that is not the case as well.

I suspect this is because the Multiplus is changing output Hz and the UPS is reacting to it.

The UPS’s sensitive is set to low (high/medium/low being the only options). I’ve talked to Cyperpower support and they can’t give me much more info, although they suspect it is due to the ‘slew’ out of the Victron system.

So the question is …

Is there anything I can do on the Victron side to shield the UPS from the Hz changes, or otherwise eliminate them?

2

The answer to the primary question is to reprogram the PV inverter to throttle between 60Hz (100% output) and 61Hz (0% output), similarly the rest of the system.

However, I’m a bit confused as to the complexity of your topology: The multiplus has an internal transfer switch that is very good. It also has a UPS mode, which makes it better. This is adequate to protect pc’s etc. The use of a second UPS seems to be redundant.

3

Thank you.

What I am trying to accomplish with this setup is to use as much solar as possible - for charging the batteries and powering my home lab.

The way I understand it, is that if I have the Multiplus turned on for both inverter and charger then the charger will charge the battery when the solar can not. For example at night. I don’t want that, I want the battery to deplete at night, so it can be charged the next day by solar.

The set up I have, with the charger virtually always off, allows me to charge the battery in such a way that is is only charged via solar - while still discharging 24 hours a day.

Problem is every so often, the batteries get low (too many cloudy days, winter months) and I have to go to grid power. At that point, I just turn the invert off - the ATS then sends the power from the grid to the UPS in front of the home lab.

Also, the UPS rides out any bumps when the Multiplus goes on and off in terms of the inverter.

Regarding:

… reprogram the PV inverter to throttle between 60Hz (100% output) and 61Hz (0% output), similarly the rest of the system.

again thank you - but how is that done?

4

If you program the inverter to “ignore ACin” then this won’t use the AC input until the battery is low.
change over is good, and you can program a really low charge current from the mains to the battery, so the battery won’t recharge from mains, but wait for the next sunny day.

For the Victron equipment, this is in the Configuration of the PV assistant, for the PV inverter - see the instruction manual.