4 ms·

Oh certainly it is important to have some kind of cut-off to prevent back-feeding the power lines, but I thought that would just be part of the system design.

lazide 4y ago
It is! The easiest design is to require existing grid stable power and supplement it. :) Anything else is difficult to do reliably, and would generally require some kind of smart monitoring system, electrically actuated mains rated switch (not easy, cheap or durable it turns out), additional sensors, etc. The design we're talking about just doesn't output power unless there is an existing sine wave to follow. Pretty foolproof, since anything that provided it would also be the one responsible for electrocuting the worker.
- TaylorAlexander 4y ago
  That makes sense! I guess being new to this it is just counter intuitive to think that you could install a big solar panel system and still suffer power outages. But I see what you mean.
- fragmede 4y ago
  I’m typing this from a computer I’m holding in my hand that’s more powerful than the ones used to put men on the moon. A box with three connections - grid, solar, and house (four if you have a battery) with sensors and disconnects and the smarts to not backfeed and electrocute linemen just doesn’t seem impossibly complex. Especially when we’re talking about home solar installs, which cost several thousand dollars to begin with. There’s got to be some other force at play here preventing this device, which is the most obvious way of implementing a supplementary power system connection, from being widespread.
  - lazide 4y ago
    They do exist. Does your handheld box switch up to 48 kw under load? Because that’s the typical rating for a new residence in most areas in the US (200 amp x 240 volt). Is your handheld device rated to last 20+ years in an outdoor environment? Because that’s what you’d need. But don’t worry, just the switch itself is only about $700-800 without labor, installation, or maintenance - [https://www.electricgeneratorsdirect.com/Generac-RXSW200A3/p77435.html https://www.electricgeneratorsdirect.com/Generac-RXSW200A3/p...] Add in all the other stuff and an extra couple thousand to the cost of the solar installation is why it isn’t as common. Because most people don’t care enough to pay the extra amount. Some do. If you wanted it enough to pay the extra, most electricians wouldn’t mind adding it in I’m sure.
throwaway0a5e 4y ago
To the breaker on your solar (or genset) the resistance of the neighborhood is gonna look indistinguishable from a short circuit so you'll need to at least disconnect from the grid if you want to power your house. From there your next problem is that solar panels don't handle being overloaded very well so you either need a ton of them ore batteries.
- lazide 4y ago
  Often, but not always. There are a number of ways lines can and do fail that produce high impedance, including a tree downing a service connection, breaker tripping, etc.

lazide 4y ago

It is! The easiest design is to require existing grid stable power and supplement it. :) Anything else is difficult to do reliably, and would generally require some kind of smart monitoring system, electrically actuated mains rated switch (not easy, cheap or durable it turns out), additional sensors, etc. The design we're talking about just doesn't output power unless there is an existing sine wave to follow. Pretty foolproof, since anything that provided it would also be the one responsible for electrocuting the worker.

TaylorAlexander 4y ago
That makes sense! I guess being new to this it is just counter intuitive to think that you could install a big solar panel system and still suffer power outages. But I see what you mean.
fragmede 4y ago
I’m typing this from a computer I’m holding in my hand that’s more powerful than the ones used to put men on the moon. A box with three connections - grid, solar, and house (four if you have a battery) with sensors and disconnects and the smarts to not backfeed and electrocute linemen just doesn’t seem impossibly complex. Especially when we’re talking about home solar installs, which cost several thousand dollars to begin with. There’s got to be some other force at play here preventing this device, which is the most obvious way of implementing a supplementary power system connection, from being widespread.
- lazide 4y ago
  They do exist. Does your handheld box switch up to 48 kw under load? Because that’s the typical rating for a new residence in most areas in the US (200 amp x 240 volt). Is your handheld device rated to last 20+ years in an outdoor environment? Because that’s what you’d need. But don’t worry, just the switch itself is only about $700-800 without labor, installation, or maintenance - [https://www.electricgeneratorsdirect.com/Generac-RXSW200A3/p77435.html https://www.electricgeneratorsdirect.com/Generac-RXSW200A3/p...] Add in all the other stuff and an extra couple thousand to the cost of the solar installation is why it isn’t as common. Because most people don’t care enough to pay the extra amount. Some do. If you wanted it enough to pay the extra, most electricians wouldn’t mind adding it in I’m sure.

throwaway0a5e 4y ago

To the breaker on your solar (or genset) the resistance of the neighborhood is gonna look indistinguishable from a short circuit so you'll need to at least disconnect from the grid if you want to power your house. From there your next problem is that solar panels don't handle being overloaded very well so you either need a ton of them ore batteries.

lazide 4y ago
Often, but not always. There are a number of ways lines can and do fail that produce high impedance, including a tree downing a service connection, breaker tripping, etc.