If you expect your solar panels to power your house when the grid goes down, make sure you check that. They most likely will not, unless you've added a battery and switches.
NERC sounds alarm on solar tripping in ‘sobering’ summer reliability report
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Re: NERC sounds alarm on solar tripping in ‘sobering’ summer reliability report
#12If you expect your solar panels to power your house when the grid goes down, make sure you check that. They most likely will not, unless you've added a battery and switches.
And an inverter!
Re: NERC sounds alarm on solar tripping in ‘sobering’ summer reliability report
#13I'm having trouble with the power industry terminology. I /think/ they mean there's going to be more demand, which could overload parts of the distribution grid, causing its overload protections to trip. Is that right? The solar connection is not clear aside from it contributing more power on the grid when it's sunny.
Not exactly. The concern raised in the article is that rooftop solar can disconnect off the grid automatically causing a small problem to be cascade to a larger one. https://news.ycombinator.com/item?id=31463342 has a ton of good info on this
Re: NERC sounds alarm on solar tripping in ‘sobering’ summer reliability report
#14> But the biggest long-term risk may be the unexpected tripping of solar resources during grid disturbances, This is entirely the electricity grids own doing. They told everyone who wanted solar that they must use inverters that are super safe and self disconnect if anything unexpected happens. The regulations were written super tight, with frequency limits, harmonic limits, reactive power limits, rate of change of f…
Last year, I had the opportunity to talk to some PG&E-associated contractors [0] who were replacing the distribution transformer serving me. I asked them whether they trusted the anti-islanding protection in everyone’s inverters and whether they would like me to turn off my main breaker. They laughed and said that they couldn’t care less. They were going to intentionally short the secondary circuit if they were doing dangerous work, and if anyone’s inverter was trying to energize it, that was the inverter’s problem.
I’m genuinely unsure what purpose anti-islanding actually serves.
(My inverter is moderately intelligent and formed a one-house microgrid all by itself. That being said, this capability may be at odds with helping the grid survive a major disturbance. When my inverter decides to disconnect from the grid, it cannot support the grid regardless of what its software and the regulators think.)
[0] By which I mean line workers at a company that PG&E contracts with to maintain their distribution network. Apparently PG&E outsources real work. Go figure.
Re: NERC sounds alarm on solar tripping in ‘sobering’ summer reliability report
#15If you expect your solar panels to power your house when the grid goes down, make sure you check that. They most likely will not, unless you've added a battery and switches.
And an inverter!
The battery is largely optional. The critical bits are the switch, aka “microgrid interconnection device”, and the inverter’s ability to make a decent sine wave without grid assistance.
Re: NERC sounds alarm on solar tripping in ‘sobering’ summer reliability report
#16Earlier quoted context omitted.
And an inverter!
The battery is largely optional. The critical bits are the switch, aka “microgrid interconnection device”, and the inverter’s ability to make a decent sine wave without grid assistance.
Only kind of. Without a battery your power will go out every time a cloud covers the sun, unless you have a hugely oversized array.
Re: NERC sounds alarm on solar tripping in ‘sobering’ summer reliability report
#17I'm having trouble with the power industry terminology. I /think/ they mean there's going to be more demand, which could overload parts of the distribution grid, causing its overload protections to trip. Is that right? The solar connection is not clear aside from it contributing more power on the grid when it's sunny.
Solar cells generate DC, but this is converted to AC with power electronics: the inverter is the main one. These are all just very high wattage semiconductors, but like all semiconductors, they can be destroyed by a transient event like a lightning strike, or a high fossil-fuel power plant dropping offline. To prevent the power electronics from being destroyed when this happens, they are protected by safety systems which "trip," and isolate them from the grid.
There are loads of designs for grid isolation, but most are big circuit breakers, and break the connection by rotating the conductor out of contact, powered by gravity or a spring.
So I think you're basically right, and right to be confused. The solar connection of the risk isn't really clear. But as far as I can tell, they're concerned about a positive feedback loop, where a thermal plant dropping offline will cause a solar plant to trip, which might cause other solar plants to trip. Perhaps solar plants' power electronics are more delicate, and more likely to trip, than thermal plants' switchyard gear. Again, it's not totally clear.
Re: NERC sounds alarm on solar tripping in ‘sobering’ summer reliability report
#18> But the biggest long-term risk may be the unexpected tripping of solar resources during grid disturbances, This is entirely the electricity grids own doing. They told everyone who wanted solar that they must use inverters that are super safe and self disconnect if anything unexpected happens. The regulations were written super tight, with frequency limits, harmonic limits, reactive power limits, rate of change of f…
It’s such an own goal to take massively distributed and resilient power generation with no inherent single point of failure and just give it one anyway.
Re: NERC sounds alarm on solar tripping in ‘sobering’ summer reliability report
#19> But the biggest long-term risk may be the unexpected tripping of solar resources during grid disturbances, This is entirely the electricity grids own doing. They told everyone who wanted solar that they must use inverters that are super safe and self disconnect if anything unexpected happens. The regulations were written super tight, with frequency limits, harmonic limits, reactive power limits, rate of change of f…
Indeed, came here to write basically this. Solar tripping off is solar obeying the rules set on them by the utility that is "You will trip if anything so much as looks funny."
And then a few decades later, they figured out this was a terrible idea and the newer 1741-SA/CA Rule 21/etc stuff with far greater ridethrough for reasonable disturbances showed up, but I don't think it's the majority of solar installs.
I should probably get a Grid Guard code for my SMA inverters and use the revised ridethrough rules - my utility handwaved at it when I installed stuff, and it's using the CA Rule 21 stuff, but they now have far more explicit guidelines on what they want programmed in the inverters.
Re: NERC sounds alarm on solar tripping in ‘sobering’ summer reliability report
#20> But the biggest long-term risk may be the unexpected tripping of solar resources during grid disturbances, This is entirely the electricity grids own doing. They told everyone who wanted solar that they must use inverters that are super safe and self disconnect if anything unexpected happens. The regulations were written super tight, with frequency limits, harmonic limits, reactive power limits, rate of change of f…
Last year, I had the opportunity to talk to some PG&E-associated contractors [0] who were replacing the distribution transformer serving me. I asked them whether they trusted the anti-islanding protection in everyone’s inverters and whether they would like me to turn off my main breaker. They laughed and said that they couldn’t care less. They were going to intentionally short the secondary circuit if they were doing…
> I’m genuinely unsure what purpose anti-islanding actually serves.
I think it mostly prevents inverters from trying to destroy themselves feeding into a dead short, or creating weird instabilities - the grid segment is either up or down from the inverter's point of view. Any sane inverter will detect it's trying to feed a dead short and shut down. And if you're grid tied and your grid segment is down, it looks like a dead short.
It's a useful enough filter for people who understand power systems and power system work, because, as your linemen pointed out, if safety is a question, the workers simply create a bolted short across all the phases and neutral, and you're not simply not going to make that ring.
And, yes, migratory line workers are a thing. I don't get it, but relatively few people I've talked to out here (Idaho Power territory) actually work for Idaho Power - it's mostly migratory contract workers doing the power pole inspections and such.