Inverter disconnecting and reconnecting

[Diabe]

Inverter disconnecting and reconnecting

Hey everyone. On my Shed I have a Growatt 3600-tl inverter with 10 solar panels on 1 string.

For some reason lately when it is nice weather the inverter disconnects and reconnects.

There are no error codes.

I am measuring around 250 Volt AC at the inverter on a socket.
Meanwhile at my distribution box im measuring around 243 VAC on the same cable.

Could a too high AC voltage cause my inverter to disconnect?

 

[kommando]

Yes, if your cable from inverter to your house Dist box is too small you will get voltage spikes at the inverter and it will disconnect based on the grid voltage being too high. Long term solution is to increase the gauge of the AC wire from inverter to dist box, short term adjust the Inverter disconnect AC Grid top setting higher. Note there could also be a 10 min average AC V setting that needs altering too.

 

[Diabe]

Thank you, what diameter wire would you recommend? It is 2.5mm2 at the moment

 

[kommando]

I went to 6mm2 to sort my same issue out, well I knew in advance it was going to be an issue so it was planned from the start. That will take 32A but more importantly the voltage drop is a lot lower over long distances, in the UK there is only 4mm2 available between 2.5mm2 and 6mm2 and for the difference in price 6mm2 was more certain to fix the issue. Plus my Inverter is on the end of a 20M run so 6mm2 was more sensible.

 

[Steve_S]

For some reason lately when it is nice weather the inverter disconnects and reconnects.

Well there is the FLAG right there.
You didn't clarify. Is your inverter disconnecting FROM the batteries & then shutting down your AC Output ?
IF that is the case, it is your battery packs causing the issue here. I say that because you say "it is nice weather" therefore charging.

- When your battery packs reach FULL the BMS will reduce charge as resistance within the packs increases until the packs / system reaches Endamps/Tailcurrent at which point the system should switch to FLOAT mode. That is the NORMAL operation.

- Alternately, when charging IF a single cell reaches 3.650V the OVP (Over Volt Protection) kicks in and shuts off Charge altogether. When that happens the Inverter disconnects from the battery because it sees no battery voltage. Some inverter systems can continue operations with just solar power incoming and just reconnect when the batteries "reappear" but this is not usual and can actually be problematic. (there is history).

You NEED to determine which Cause is creating this issue.
Most often it is the battery packs reaching OVP and cutting off, which of course drops the Inverter and everything attached thereto.

The GOTCHA !
LFP has two Voltage Ranges like ALL BATTERIES DO !
The Allowable range where NO harm is done to the cells is 2.500-3.650 but this is NOT intended to be used daily.
The Working Range which is what Manufacturers test & Validate cells to, and is responsible for delivering the rated AH is 3.000-3.400 with Nominal Voltage being 3.200 (50% SOC).
Far too many People & even Companies try to push that envelope and end up suffering issues, sometimes with terrible consequences.
A Moderate & Reasonable Charge profile that does not push cells beyond working voltages will prevent OVP/UVP conditions and keep you happily running for years.

SETTING​	V per cell​	12V​	24V​	48V​	notes​
Bulk / Absorb: (boost)​	3.425​	13.8​	27.6​	55.2​	Absorb < 60min Transitions to Float​
Equalize: ​	0​	​	​	​	NOT for Lithium Based Batteries​
Float​	3.437​	13.75​	27.5​	55.0​	allows cells to balance internally​
Min Volts:​	2.650​	10.6​	21.2​	42.4​	Never allow to drop too low. Safe Buffer​
Max Volts:​	3.575​	14.3​	28.6​	57.2​	​
Rebulk Voltage:​	3.200​	12.8​	25.6​	21.2​	​
End Amps / Tail-Current:​	​	​	​	​	formula: 100AH X 0.05 = 5A​

 

[Diabe]

Thanks for the replies. I will be replacing my 2.5mm2 cable for 6mm2 when i get the chance.

I have no batteries so that is not the problem