Running portable generator connected to main panel without messing up the solar setup

[hurnik]

Currently have a 10.3kw solar panel system with two SMA inverters. I'm grid-connected and net-metered so any excess is back-fed to the utility company (National Grid). Obviously when the power is out, so is the solar. That's fine. I understand why.

We recently had a 3 day power outage due to storms last month (of course, the sunniest days of October--haha). I ended up getting a portable generator to hook up a few things (extension cord setup--not terribly convenient but I had power). I want to connect to main panel (but not via transfer switch, using one of those Reliance Controls connector with the cable and the interlock kit for my Cutler Hammer panel and the 30-amp breaker).

I THINK that this would be an OK setup since the main has to be turned off in order to turn on the 30 amp breaker for the generator. But wanted to make sure that this would not trick the PV system into thinking it was "OK" to fire up (we don't want that to happen).

I tried Googling and searching here, but it seems all I can find is people who WANT the generator to trick the inverters into running.

[bcroe]

My rule is, both the main breaker AND the solar net metering inverters must be shut
off before connecting my emergency (4.5KVA) gas generator. Bruce Roe

[PVAndy]

Currently have a 10.3kw solar panel system with two SMA inverters. I'm grid-connected and net-metered so any excess is back-fed to the utility company (National Grid). Obviously when the power is out, so is the solar. That's fine. I understand why.

We recently had a 3 day power outage due to storms last month (of course, the sunniest days of October--haha). I ended up getting a portable generator to hook up a few things (extension cord setup--not terribly convenient but I had power). I want to connect to main panel (but not via transfer switch, using one of those Reliance Controls connector with the cable and the interlock kit for my Cutler Hammer panel and the 30-amp breaker).

I THINK that this would be an OK setup since the main has to be turned off in order to turn on the 30 amp breaker for the generator. But wanted to make sure that this would not trick the PV system into thinking it was "OK" to fire up (we don't want that to happen).

I tried Googling and searching here, but it seems all I can find is people who WANT the generator to trick the inverters into running.

You don't ever want you inverter to be connected to a non inverter based generator. Neither the inverter or the generator can absorb power. Strong potential they will both be damaged.


Andy

[solardreamer]

Currently have a 10.3kw solar panel system with two SMA inverters. I'm grid-connected and net-metered so any excess is back-fed to the utility company (National Grid). Obviously when the power is out, so is the solar. That's fine. I understand why.

We recently had a 3 day power outage due to storms last month (of course, the sunniest days of October--haha). I ended up getting a portable generator to hook up a few things (extension cord setup--not terribly convenient but I had power). I want to connect to main panel (but not via transfer switch, using one of those Reliance Controls connector with the cable and the interlock kit for my Cutler Hammer panel and the 30-amp breaker).

I THINK that this would be an OK setup since the main has to be turned off in order to turn on the 30 amp breaker for the generator. But wanted to make sure that this would not trick the PV system into thinking it was "OK" to fire up (we don't want that to happen).

I tried Googling and searching here, but it seems all I can find is people who WANT the generator to trick the inverters into running.

You need to shut off main panel breakers to grid and SMA inverters before connecting a generator. Both inverter and non-inverter generators can activate grid-tied inverters without the grid. However, non-inverter generators most likely won't be able to maintain it while inverter generators will and result in damage if there is not enough loads to absorb power from the grid-tied inverters.

[Mike90250]

You don't ever want you inverter to be connected to a non inverter based generator. Neither the inverter or the generator can absorb power. Strong potential they will both be damaged.

Andy

I'll add to this, you never want your PV inverter to see/connect to any generator. The instant the PV produces more than your generator loads, something is likely to fry, and it will be the smaller device . PV inverter or your generator. The voltage spike may trip the inverter off line a few times and re-sync, but eventually the abuse will fry something.

[Sunking]

This is what happens when the clueless play with electricity. The have no clue how much danger they place themselves in, and could care less what danger they put others in.

[hurnik]

Thanks for all the info.

I'm curious though as to why or how a portable (non-inverter generator) could trick the SMA inverters into thinking there was power, IF the main breaker is off (interlock kit basically ensures that, does it not? as it won't let you turn on the generator-tied breaker unless the main is off) and it's (the generator) connected to a 30-amp breaker in the panel.

Is there some sort of "leakage" that gets past the main breaker? If so, then that would mean even without Solar, that the electrical crews could get zapped whilst working on the line, right?

[sdold]

Thanks for all the info.

I'm curious though as to why or how a portable (non-inverter generator) could trick the SMA inverters into thinking there was power, IF the main breaker is off

Unless you have a "Line Side Tap" where the solar feeds the grid "upstream" of the main breaker, the SMA inverters likely feed the panel bus through dedicated breakers, so they would "see" the generator's voltage even if the main breaker was open, unless you remember to open them.

Also this wouldn't happen if you're using one of the "Load side" transfer panels that lets you select a few circuits to run from the generator, essentially a manual transfer switch for each branch circuit.

[hurnik]

Unless you have a "Line Side Tap" where the solar feeds the grid "upstream" of the main breaker, the SMA inverters likely feed the panel bus through dedicated breakers, so they would "see" the generator's voltage even if the main breaker was open, unless you remember to open them.

Also this wouldn't happen if you're using one of the "Load side" transfer panels that lets you select a few circuits to run from the generator, essentially a manual transfer switch for each branch circuit.

Thanks. In my case it’s a line side tap. The solar panels do not feed the panel via dedicated breakers.

however I see nothing wrong or bad with shutting off the inverters since I’d have to go outside and hook up the generator anyway.

transfer switch is a little limiting for what I’d prefer although I understand what you’re saying now.