4 ms·

> The hacker in me hates it too but just imagine if a small portion of standard-looking outlets did not output 220V (or whatever standard you have) and say 330V

by baq 3y ago

> The hacker in me hates it too but just imagine if a small portion of standard-looking outlets did not output 220V (or whatever standard you have) and say 330V. Overvoltage is now routine in places where there's lots of PV installed in homes and not enough load nearby. If you live in such a place, you have a deep appreciation of varistors and should have either good insurance or a little bit of soldering skills... preferably both.

xenadu02 3y ago
> Overvoltage is now routine in places where there's lots of PV installed in homes and not enough load nearby. Every solar inverter / microinverter manufactured in the past two decades (if not older) must monitor the grid voltage+frequency and disconnect if it falls outside of a certain tolerance. If things go out of tolerance there is a defined period of time where it must recover or the inverter is required to trip out. There are also hard safety limits that cannot be exceeded whatsoever. I am not aware of any conditions that would result in overvoltage. In CA as of (IIRC) 2021 these systems must be hooked up to some kind of online monitoring so the utility can temporarily command them to exceed tolerances. If the grid is going unstable due to load the last thing you want is everyone's PV system tripping off making the supply situation worse. So the utility can inform the system to exceed the normally tight tolerances by a larger deviation. They can also command PVs systems to shut off but there are strict limits on how often and how long they can do that and it must be driven by grid stability needs.
- baq 3y ago
  Yes, absolutely, same here. The problem is varistors blow out before the safety measures work. Perhaps due to wear or low quality, but this still happens.
  - xenadu02 3y ago
    I'm not sure how a single inverter failure could drive voltage high. Or how a varistor failure could cause a problem... The inverter has to perform a DC-AC conversion and has many more ways to fail safe than unsafe but I'm not saying it is impossible. I've seen some oddball things. But it certainly isn't a widespread issue. Smart meters report voltage, the utilities would know if this was happening and given how much they hate rooftop solar they'd be yelling about it if they could.

by baq 3y ago

xenadu02 3y ago

> Overvoltage is now routine in places where there's lots of PV installed in homes and not enough load nearby. Every solar inverter / microinverter manufactured in the past two decades (if not older) must monitor the grid voltage+frequency and disconnect if it falls outside of a certain tolerance. If things go out of tolerance there is a defined period of time where it must recover or the inverter is required to trip out. There are also hard safety limits that cannot be exceeded whatsoever. I am not aware of any conditions that would result in overvoltage. In CA as of (IIRC) 2021 these systems must be hooked up to some kind of online monitoring so the utility can temporarily command them to exceed tolerances. If the grid is going unstable due to load the last thing you want is everyone's PV system tripping off making the supply situation worse. So the utility can inform the system to exceed the normally tight tolerances by a larger deviation. They can also command PVs systems to shut off but there are strict limits on how often and how long they can do that and it must be driven by grid stability needs.

baq 3y ago
Yes, absolutely, same here. The problem is varistors blow out before the safety measures work. Perhaps due to wear or low quality, but this still happens.
- xenadu02 3y ago
  I'm not sure how a single inverter failure could drive voltage high. Or how a varistor failure could cause a problem... The inverter has to perform a DC-AC conversion and has many more ways to fail safe than unsafe but I'm not saying it is impossible. I've seen some oddball things. But it certainly isn't a widespread issue. Smart meters report voltage, the utilities would know if this was happening and given how much they hate rooftop solar they'd be yelling about it if they could.