At long last - our solar PV is in - but questions about operation

[Radian]

Finally had our little 3.2kW system installed today after being on the waiting list for over six months.

 

 

All good It seems but the Solis S6 inverter is a new one to me and the operating instructions regarding start-up and shutdown seem odd. With other inverters, I'm used to staring up by switching on the DC first then AC. And the opposite when shutting down. But these snips from the Solis manual say:

 

5.1 Start the Inverter

To start up the Inverter, it is important that the following steps are strictly followed:

1. Switch the grid supply main Switch (AC) ON first.

2. Switch the DC switch ON.

 

So, it's important that the above steps are strictly followed? And when power is restored after a power cut? The shutdown is just as weird:

 

5.2 Stop the Inverter

To stop the inverter, it is mandatory that the steps below are followed in the exact order outlined.

1. Select "Grid Off" in the Advanced Setting of Inverter LCD.

2. Turn off the AC Switch between Solis inverter and Grid.

 

Fine if you've got access to the advanced settings and have prior notification of a power-cut. Still, it's only mandatory.🙄

What are they on about?

[MikeSharp01]

10 minutes ago, Radian said:

So, it's important that the above steps are strictly followed? And when power is restored after a power cut? The shutdown is just as weird:

Looks like a little job for an Rpi, some current transducers, a small UPS, and a couple of contactors to shut the DC down as the grid power is turned off and then bring it back up in the correct order when power is restored. MIght work with a simpler scheme of just driving the DC contactors from the mains with a small on delay. Wish I had time to play.

[willbish]

I have similar but larger Solis inverter, religiously followed the strict instructions initially. But after a few grid power cuts, the inverter seems quite content to power down and reboot in any AC/DC order. 

Maybe I've affected the longevity of the machine but I doubt it.

[ProDave]

I think the only golden rule is DO NOT open the DC isolator when the inverter is running.

 

Normally both isolators remain on and it just operates, starting up and shutting down each day, and coping with grid power cuts.  The isolators are there for when you want to work on the system, either the panels or to change the inverter.

[Radian]

The installation guys seemed to think it just didn't matter but like @ProDave says, the one thing that really matters is not disconnecting the DC when under load. I'm surprised they didn't point that out.