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> It also makes you more immune to losing power in a natural disaster, of which California has plenty. Unfortunately, this is generally not the case. Most gri

> It also makes you more immune to losing power in a natural disaster, of which California has plenty. Unfortunately, this is generally not the case. Most grid-tie solar inverters do not support disconnected operation. They all have anti-islanding features that disconnect the solar panels when the grid goes down (to prevent back-flow into the grid that could injure linemen working to repair outages). There are a few inverters that include an emergency-outlet on the inverter that works when the power is out, but you have to run an extension cord from the inverter to the devices you want to power. It is possible to buy a hybird off-grid inverter, but they are much more expensive than either plain grid-tie or off-grid, and the power company is going to scrutinize their installation a lot more closely.

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mehrdadn 9y ago
> to prevent back-flow into the grid that could injure linemen working to repair outages Surely they can't entirely rely on this for safety?
- aerostable_slug 9y ago
  Backfeed prevention devices are not the only arrow in the safety quiver, but they are required for lineman safety purposes (as well as other net wins, like reduced problems with downed lines meeting up with everyday people). Backfed generators (and now solar, wind, etc.) injure and kill.
dsfyu404ed 9y ago
>(to prevent back-flow into the grid that could injure linemen working to repair outages) Back-flows from generators, solar and other home power sources are not really an issue. It takes a specific set of circumstances where there's both equipment failure and the utility worker fails to check if lines are live. Basically, the resistance of the entire neighborhood is indistinguishable to a short from the perspective of the breakers on your power generation equipment. Still, you shouldn't back feed because we live in a society where everyone must play by the rules of idiots regardless of whether or not they can prove themselves to be otherwise. Therefore you cannot be trusted to flip switches properly yourself and I must advise you to use a proper transfer switch.
- mulmen 9y ago
  Aren't shorts very low resistance? I'm not an electrician so maybe I misunderstand here. What would be the benefit of me "properly flipping switches" in the context of a natural disaster? What if I am not home?
  - hunter2_ 9y ago
    Yes, and so is a neighborhood. A dim lightbulb has a high resistance. A bright lightbulb has a lower resistance. Multiple bright lightbulbs in parallel, measured together as one, have an even lower resistance.
    - mulmen 9y ago
      I don't follow. How does a neighborhood become both high and low resistance?
      - posterboy 9y ago
        Where did anyone imply that?
- MertsA 9y ago
  It's not powering the whole neighborhood that's the problem. With downed lines it very well might not put any significant load on the inverter yet still have a significant amount of downed distribution lines live. Normally the fire department or the power company can just take a hot stick and within a couple minutes pull out the fuse upstream of a segment and ground out the lines making it safe from the rest of the grid. With improperly installed generators every house is a potential source of power, there's no quick and easy way to isolate all of them like their is with utility power, and grounding out every segment might not be as easy to do reliably as with utility power. If you ground out the line upstream of the fault then you know with certainty that utility power isn't going to somehow energize the portion of line being worked on but when it's being fed from more than one direction there could be a fault that isn't readily apparent that creates a dangerous situation where a linesman thinks a line is safe when it is live being powered by a generator.
panarky 9y ago
Or use a Powerwall https://en.wikipedia.org/wiki/Tesla_Powerwall https://en.wikipedia.org/wiki/Tesla_Powerwall
anigbrowl 9y ago
This seems like a simple problem to solve, by putting the inverter at the periphery of the domestic system.

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mehrdadn 9y ago

> to prevent back-flow into the grid that could injure linemen working to repair outages Surely they can't entirely rely on this for safety?

aerostable_slug 9y ago
Backfeed prevention devices are not the only arrow in the safety quiver, but they are required for lineman safety purposes (as well as other net wins, like reduced problems with downed lines meeting up with everyday people). Backfed generators (and now solar, wind, etc.) injure and kill.

dsfyu404ed 9y ago

>(to prevent back-flow into the grid that could injure linemen working to repair outages) Back-flows from generators, solar and other home power sources are not really an issue. It takes a specific set of circumstances where there's both equipment failure and the utility worker fails to check if lines are live. Basically, the resistance of the entire neighborhood is indistinguishable to a short from the perspective of the breakers on your power generation equipment. Still, you shouldn't back feed because we live in a society where everyone must play by the rules of idiots regardless of whether or not they can prove themselves to be otherwise. Therefore you cannot be trusted to flip switches properly yourself and I must advise you to use a proper transfer switch.

mulmen 9y ago
Aren't shorts very low resistance? I'm not an electrician so maybe I misunderstand here. What would be the benefit of me "properly flipping switches" in the context of a natural disaster? What if I am not home?
- hunter2_ 9y ago
  Yes, and so is a neighborhood. A dim lightbulb has a high resistance. A bright lightbulb has a lower resistance. Multiple bright lightbulbs in parallel, measured together as one, have an even lower resistance.
  - mulmen 9y ago
    I don't follow. How does a neighborhood become both high and low resistance?
    - posterboy 9y ago
      Where did anyone imply that?
MertsA 9y ago
It's not powering the whole neighborhood that's the problem. With downed lines it very well might not put any significant load on the inverter yet still have a significant amount of downed distribution lines live. Normally the fire department or the power company can just take a hot stick and within a couple minutes pull out the fuse upstream of a segment and ground out the lines making it safe from the rest of the grid. With improperly installed generators every house is a potential source of power, there's no quick and easy way to isolate all of them like their is with utility power, and grounding out every segment might not be as easy to do reliably as with utility power. If you ground out the line upstream of the fault then you know with certainty that utility power isn't going to somehow energize the portion of line being worked on but when it's being fed from more than one direction there could be a fault that isn't readily apparent that creates a dangerous situation where a linesman thinks a line is safe when it is live being powered by a generator.

panarky 9y ago

Or use a Powerwall https://en.wikipedia.org/wiki/Tesla_Powerwall https://en.wikipedia.org/wiki/Tesla_Powerwall

anigbrowl 9y ago

This seems like a simple problem to solve, by putting the inverter at the periphery of the domestic system.