Hacker Neue

Preferences
Ekaros parent
Because they are potentially deadly in certain failure states. Normally system you expect system to be dead when main switch is turned off. But in this case something might be feeding in power. Same goes for over current protection. You really do not want power when you expect there to be none. Even if you should always check.
the-unknown-dev
This is not really an issue. The inverters used in these cases rely on an existing power supply for synchronization with the electrical grid. If there is no power on the socket, the inverter has no means to generate a sine wave on its own and does not provide power on its cable.

This is true (as far as I know) for ALL inverters, apart from "off grid" solutions, so workers can turn off power on a street level. If that wasn't the case, there would be no way for technical staff to make sure that lines going to multiple homes (with solar) are powered off.

davrosthedalek
I can how it would not switch on if line power is gone. But what if it is on already, there are not many loads on, and the mains go down? Does it switch off? How does it know?
bluGill
It watches the incoming AC waveform and matches that. If there is no waveform it has nothing to match and so it shuts off.
davrosthedalek
How do you watch the incoming waveform if you drive your own waveform on the same line? I guess you could look periodically.
floitsch
Balcony solar requires the 50Hz of the energy grid. If you turn off the main power they will stop feeding into the system.
tengbretson
So if enough of your neighbors have these panels then the grid never gets turned off.
WJW
Technically probably yes, provided you had millions of neighbors, the sun never sets and all big users like kettles and heat pumps kindly switch off as well. If either of those conditions stops being true, then either the frequency or the voltage will drop too much and the panels turn themselves off. In practice these balcony panels are not sufficient in the slightest to power a house, let alone an entire apartment building, and they will turn off almost instantly.
bluGill
READ THE OTHER REPLIES FIRST. I'm going to assume you did as they are right about what this can't happen.

When you backfeed like that your neighbors will draw on your power - but they will attempt to draw more than you can provide and so your circuit breakers will trip. The only way backfeeding could be an issue is if you have a very large generator and the area islanded is only a couple neighbors such that the total power use is less than the theoretical max of your house.

That said, linemen are trained to either treat all wires as live or short them to ground. They can never be sure they are not in that rare exception case and mistakes can be deadly.

Limeray (dead)

This item has no comments currently.

Keyboard Shortcuts

Story Lists

j
Next story
k
Previous story
Shift+j
Last story
Shift+k
First story
o Enter
Go to story URL
c
Go to comments
u
Go to author

Navigation

Shift+t
Go to top stories
Shift+n
Go to new stories
Shift+b
Go to best stories
Shift+a
Go to Ask HN
Shift+s
Go to Show HN

Miscellaneous

?
Show this modal