Good morning

I am unable to find the correct procedure for my RCT Infinisolar inverters.

I have 2x inverters in parallel, each with their own PV string. I have 2x lithium batteries running in parallel and connected to both inverters. I also have Eskom as AC in for both inverters.

I would like to know in which order should I start or switch off each component.

Thanks

What has worked for me

Disconnect PV

Disconnect Battery

Flip inverter switch off

Disconnect Eskom

The previous time I switched the PV off, my DC circuit breaker arc'ed and went up in flames. After reading up on it I understand that this will always happen if you disconnect PV under load. So the reason for my question is to get the correct order so I'm certain there is no load on the PV when I switch it off.

I have since changed to a rotary PV disconnector instead of the DC circuit breaker. Will that maybe enable me to disconnect the PV even under load without a fire hazard? I was hoping to confirm everything before putting it to the test.

Forgot to mention, I use my changeover switch to Eskom/AC to carry all loads prior to any of the above.

You could isolate battery first, then inverter switch off (inverter stays on, just doesn supply any load or charge battery), then PV and Eskom and that should be a full cold shutdown

Thank you for the feedback. The inverter that stays on was making me wonder about the load on the PV

I'll see if I can get a few more opinions so I can decide on my own procedure.

19 minutes ago, diy-offgrid said:

Thank you for the feedback. The inverter that stays on was making me wonder about the load on the PV

I'll see if I can get a few more opinions so I can decide on my own procedure.

Just some advice not all dc mcb's are rated for isolation under load so ensure to have a good quality dc isolator especially with high voltage arrays as just a few amps will cause an arc flash. Below link for Tomzn solar isolator that is rated for 1200v 32A(38.4kw) and you also get 1200v 60A(72kw).

Should you decide to disconnect the pv array from the MPPT's try and do it at night when the panels are inactive.

 

https://e-glow.co.za/products/isolator-32a-4p-1200vdc?variant=42292754120880&currency=ZAR&utm_medium=product_sync&utm_source=google&utm_content=sag_organic&utm_campaign=sag_organic&utm_campaign=gs-2022-06-01&utm_source=google&utm_medium=smart_campaign&gclid=CjwKCAiA9dGqBhAqEiwAmRpTC5JxAJV0Nip9pYeXGf_D1IGTfjhbeGOcm3-LrkF3SuQ9HsbLcFufRxoCPeoQAvD_BwE

 

 

Thanks. I have a similar disconnector now as the one in your link.

 I agree with switching off at night. Our first option would be to never switch off. Second would be at night. This procedure will be when the first two options are not an option.

It doesn't seem like there is any certainty regarding the PV shutdown on these RCT inverters. That at least means I'm not doing anything wrong. We'll just try avoid switching off under load as far as possible.