Mistsubishi Mini Split Comm Error Off Grid

[Foxfire Energy]

Hi Guys, Dan here. We just installed an Outback 8kW VFX7248 fully off grid system for a client who also purchased and installed three Mitsubishi mini split heat pumps. The Power System is performing flawlessly. The heating systems.. not so much. The customer can light up each unit individually, but when she attempts to light up more than one, the each consecutive unit trips out on comm error. If she shuts down everything (From the breaker box) she gets the same results starting from which ever unit she first started. The HVAC guys would love to blame the solar guys (as would the lawn care guys), All my guys blame the HVAC guys. I've heard of adding caps to the 240vac input, but each unit is on its own circuit, there should not be Power Factor/ harmonic distortion issue. I'm blaming bad Sushi. Advise? Thanks db

[RascoPico]

Hi Guys, Dan here. We just installed an Outback 8kW VFX7248 fully off grid system for a client who also purchased and installed three Mitsubishi mini split heat pumps. The Power System is performing flawlessly. The heating systems.. not so much. The customer can light up each unit individually, but when she attempts to light up more than one, the each consecutive unit trips out on comm error. If she shuts down everything (From the breaker box) she gets the same results starting from which ever unit she first started. The HVAC guys would love to blame the solar guys (as would the lawn care guys), All my guys blame the HVAC guys. I've heard of adding caps to the 240vac input, but each unit is on its own circuit, there should not be Power Factor/ harmonic distortion issue. I'm blaming bad Sushi. Advise? Thanks db

The Off-grid inverter has a generator power input? If so have you tried starting the heat pumps while the backup generator is assisting the inverter.
8 kw inverter should have a peak power of at leat 16 kw momentarily. This should be sufficient.
Power factor may be at fault. Some inverters can be programmed for powerfactor corection. Inductive loads will cause the powerfactor to be less than one.
Capacitor banks could help.
Good luck

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[1rellik1]

Outback has great customer service reps, give them a call.

But by having my own Outback system I can add that the Mate3 controller has settings that will address the issue you have expressed here.

[1rellik1]

Best to add this important details too:

However, with out a grid connections the battery bank size/capacity and then all associated DC conducting wire sizes will need to be "up to the task".

[servicefitter]

Is it 8 kw at 240 volts? Or sized from 24 or 48 vdc. Would not doubt that the sine wave of the power isn't compatible with the monk's or the FLA of the second mini
starting pulls the voltage way down