Temporary Diesel Generator Affecting My Solar Inverter

Our utility (SCE) has placed temporary diesel generators in our neighborhood to provide power while their underground cable repair project runs over schedule. The generators have been running for three days now. We have no problems with household power or with any of our appliances or computers, but I noticed that our solar PV production was down by almost 50% during these three days.

I checked my TED power monitoring system and noticed frequent on/off transitions in solar power generation reporting. I checked the solar inverter and I see intermittent drops to zero power production in full sun. TED shows normal build-up of PV power generation until between 10:30 am to 11 am, it differs on different days, and then it goes into on/off cycling for seemingly random time periods of up to 20 minutes to as little as a minute. The household voltage is also much more variable than usual, between 118 V and a low of 111 V.

My question is whether running my solar inverter during this temporary period is damaging to the inverter, or even for the solar panels. Also, could a varying voltage cause problems for my LEAF onboard charger or for my AV Level 2 EVSE during charging at night?

Thanks for any thoughts you folks might have.

My inverter constantly checks grid voltage and frequency. It shuts the system down if either measurement is out of tolerance. It's possible the diesel generators voltage and/or frequency may occasionally be out of tolerance causing your inverter to shut down.

LKK said:

My inverter constantly checks grid voltage and frequency. It shuts the system down if either measurement is out of tolerance. It's possible the diesel generators voltage and/or frequency may occasionally be out of tolerance causing your inverter to shut down.

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That's certainly what is causing the inverter(s) to go offline. Do you have a UPS or something else that could be closely monitoring these and reporting them to you? Then you could see how far out of spec things are getting and determine how comfortable you are with that.

Thanks for your comments. That was my thought also, I just don't know enough about inverters to know whether the behavior is potentially damaging to the inverter. I don't have a UPS but I do have a TED system that monitors voltage and kWh generation and usage. But I don't know the range of OK vs "bad" voltages.

Also, could charging at night with fluctuating voltages be bad for my LEAF's systems?

Boomer23 said:

Thanks for your comments. That was my thought also, I just don't know enough about inverters to know whether the behavior is potentially damaging to the inverter. I don't have a UPS but I do have a TED system that monitors voltage and kWh generation and usage. But I don't know the range of OK vs "bad" voltages.

Also, could charging at night with fluctuating voltages be bad for my LEAF's systems?

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Assuming it's not going outside of an expectable range I think you'll be fine. My understanding based on Phil's comments is that since it's made for the Japanese market it has a pretty good tolerance for lower voltage. What's the highest voltage you've been seeing? The other issue is the frequency but I'd hope that the utility would be using generators that can keep things within a normal range and definitely within a range that isn't going to damage things.

The voltage range was from 108 to 121.8.

We're back on grid power now, and I'm seeing no damage to either the LEAF or the inverter, so things are good, it appears.

Thanks for your comments, folks.