Strange Growatt Spec

[Brett V]

Going to the store later for supplies and was double checking the electrical requirements for the Growatt 6Kw unit.

"AC Breaker Recommendation (double pole 240V) 8AWG, 80A (Input & Output)"

This doesn't seem right to me, I'd be reluctant to use 8AWG even on a 60 amp breaker. I was planning to use a 60 amp breaker and 6AWG for a roughly 10 foot run from the inverter to my panel. Am I missing something?

 

[12VoltInstalls]

Yes.

what is the inverter?

 

[RCinFLA]

If manual recommends #8 that would imply 40 amp max. For 3kW Growatt I could not find max AC input current specified, only #8 recommended wire gauge.

Saw this in larger unit.:

AC Input/Output Connection

CAUTION!! Before connecting to AC input power source, please install a separate AC breaker between inverter and AC input power source. This will ensure the inverter can be securely disconnected during maintenance and fully protected from over current of AC input. The recommended spec of AC breaker is 40A for 4KW~6KW, 80A for 8KW~12KW.

This does not make sense against their recommendation of:

Suggested cable requirement for AC wires
Model Gauge Torque Value
4KW/5KW 10 AWG 1.4~ 1.6 Nm
6KW/8KW 8 AWG 1.4~ 1.6 Nm
10KW/12KW 6 AWG 1.6~ 1.8 Nm

That implies, 30A, 40A, or 60A breakers , respectively.


Bottomline is the input AC breaker amperage should not exceed the inverter's ACin connect relay rating used.

The AC input amperage does not necessarily relate to inverter wattage. They can have ACin to ACout passthrough amperage greater then the inverter is capable of. But ACin to ACout must pass through the ACin connect relay so the relay must carry the max ACin current.

 

[Brett V]

It's the Growatt SPF 6000T. They spec an 80 amp breaker for the 240 volt AC input and 8AWG wire. It has to be a typo.
I'm using 6AWG and a 60 amp breaker.

 

[Jgb3]

 

[Brett V]

NMB 8/3 is limited to 60°C which is 40 amps so that makes sense. I'll use a 40 amp breaker to protect the bypass rating of the Growatt but still going with NMB 6/3 because I don't like warm wires. In any case, the 80 amp beaker feeding an 8AWG listed on the sales specs has to be a misprint.

 

[Cornwallav8r]

It's the Growatt SPF 6000T. They spec an 80 amp breaker for the 240 volt AC input and 8AWG wire. It has to be a typo.
I'm using 6AWG and a 60 amp breaker.

6AWG and 60A makes sense. My 5kW uses 8AWG and 50A. Make sure you can easily switch off all inputs as well. These won't typically shut down fully unless AC, battery and PV are switched off.