Solar Inverter Power Off/On Sequence?

[d21mike]

What is the recommend sequence to Power Off my Solar Inverters and the back on?

Here is a youtube video that explains using SolarEdge but seem pretty clear.

 

[power.saver]

Just like he said, AC off first, then DC off. You never want to turn the DC off when the inverter is producing power.

Then DC on and AC on.

 

[d21mike]

Thanks.

 

[boaterva]

So what passes for the ‘AC isolator’ in the US because I sure don’t have a switch like that near my inverter and when Tesla works on mine all they do is turn it off (DC switch at the SE inverter).

I asked if there was anything else to turn off and he said no since the microinverters were instant shutdown when disconnected.

So, is this video country and/or hardware dependent?

 

[power.saver]

If nothing else, the breakers serving the inverter are a disconnect. But many jurisdictions require a separate disconnect switch like the type you would find near an A/C unit.

 

[d21mike]

If it makes any difference I do not have micro inverters. Using the DELTA Inverters Tesla is installing. But they were out here and they turned ALL 3 of them off. The 2 DC Inverters and the AC. But at the time I did not ask what was the ORDER.

 

[boaterva]

I do have an emergency disconnect outside for use by fire personnel; etc., but again, Tesla did not use that. They just turned off the SE inverter switch (DC, I assume).

What is the ‘AC inverter’ referred to? Or do you mean AC disconnect? My SE inverter is connected directly to the grid (when I had solar only, now I have a TEG and PWs).

 

[chrisbailey13]

I was told by the Tesla Electrician...Turn off the inverter first, then the breaker for the inverter. startup is in reverse, turn on the breaker, then the inverter.

Same with powerwalls. Turn off the PowerWall switch then the breaker for the PowerWall switch, turn on is that reversed.

 

[power.saver]

The thing is, you don't want to open a high current high voltage DC circuit under load. It can cause arcing and all sorts of damage to the switch contacts. By turning the AC off first, the inverter stops the DC flow, and then it is safe to turn off the DC to the inverter.

Not all electricians understand this. The crew that did my installation didn't know, and I had to explain it to them.

 

[boaterva]

Great. So we have three answers here.

The SE manual seems to say the opposite from the video. Shut down via the DC switch, wait for the ‘do not open’ warning to disappear, then turn off the AC switch/breaker.

AC on to power up the inverter circuits and then DC for the PV.

That makes sense to me. But my Tesla guy still never killed the AC breaker and I’m still wondering if the DC (inverter) switch kills everything on newer configurations.

 

[chrisbailey13]

Great. So we have three answers here.

The SE manual seems to say the opposite from the video. Shut down via the DC switch, wait for the ‘do not open’ warning to disappear, then turn off the AC switch/breaker.

AC on to power up the inverter circuits and then DC for the PV.

That makes sense to me. But my Tesla guy still never killed the AC breaker and I’m still wondering if the DC (inverter) switch kills everything on newer configurations.

The SE manual seems to agree with what I was told by the installers.

 

[d21mike]

I am the OP for this Thread and a little surprised there are so many different opinions.

I found the following which is confusing... The off seems to be like the video but the on is not?

I have Tesla Installed Delta Inverters.

Delta Inverter Troubleshooting & Repairs
Isolation Error
If your Delta inverter is displaying an Isolation Error message, it could mean that there is an internal problem with the inverter or something is wrong with the DC and AC and might result to short circuit. It also means that the inverter will not convert the power to prevent electrical problems. You can try to manually resetting the inverter by following these steps:

1. Turn off the solar supply main switch or AC isolator.
2. Turn off DC isolator.
3. Wait for 1 minute before turning the main switch or AC isolator back on.
4. Turn on DC isolator.

If the error is still there after rebooting, please contact us so that a solar technician can assist you with it.

Delta Inverter Problems, Errors & Faults: Call for Troubleshooting and Tech Support – Anew Solar: Perth Solar Systems and Repairs

Of course this is not the Manufacture or Tesla so maybe not accurate.

 

[d21mike]

Got the following from the DELTA Manual:

INVERTER TURN-ON Procedure

1. Turn on the DC disconnect (turn to “ON” position).

2. Check for inverter initialization; all 3 LED indicators are illuminated.

3. Turn on the dedicated 2-pole 240 Vac / 208 Vac circuit breaker in the building

electrical service panel (put in closed position).

4. If there is AC disconnect, turn on the AC disconnect.

5. Refer to section 5 for setup process that needs to be completed before the

inverter can begin feeding power to the grid.

INVERTER TURN-OFF Procedure

1. If there is AC disconnect, turn off the AC disconnect.

2. Turn off the dedicated 2-pole 240 Vac / 208 Vac circuit breaker in the building

electrical service panel (put in open position).

3. Turn off the DC disconnect (turn to “OFF” position).

 

[power.saver]

For the turn on procedure, AC or DC first really doesn't matter. There is no DC flow in either case. Most inverters are powered by the DC, so turning it on first lets you see the display. However by doing so, the inverter detects a grid outage, and will not start exporting energy until 5 minutes after the AC is turned on. So in some cases to avoid this, turning on the AC first allows the inverter to start exporting sooner, as it wakes up with the DC and detects that the grid is already connected (just like what happens every morning when the sun comes up).

The consistent message is when turning off an inverter, turn off the AC first then the DC.