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Automatic Transfer switches are very common in Server Rooms and datacenters where there is a Generator in use. I'm not sure why they are not more common in Sol

Automatic Transfer switches are very common in Server Rooms and datacenters where there is a Generator in use. I'm not sure why they are not more common in Solar. I have a parent with a full house generator that also has a Automatic Transfer Switch, its essentially right above the breaker box. the breaker box either gets power from the generator, OR from the power company, never both. When power comes back on, the ATS senses it, and sends a signal to the generator after 30 seconds or so that it is switching over, and to shut down.

toast0 5y ago
Grid tied home solar is usually about economics (and sometimes happy feelings), not reliability. If you want automatic transfer, you need to add storage, and a more complex inverter that can operate in bridge tied and island mode, and that cuts into the economics. You might also need to get more panels to handle projected loads during projected outages, but most net metering tarrifs I've seen won't compensate you if you over generate.
- jacquesm 5y ago
  I can assure you that reliability factors in heavily in Grid tied home solar.
  - Symbiote 5y ago
    That must depend on the area. People in the Netherlands or the UK have reliable power anyway, but there are still some home solar installations.
  - _ea1k 5y ago
    That varies greatly. In my area, the grid is extremely reliable. I rarely see systems that are setup to handle outages as the cost isn't really worth it on its own.
- LorenPechtel 5y ago
  This. Normal solar relies on the grid as it's "storage". The economics of solar become very different if you have to provide local storage. This is also why there is an ongoing fight over net metering and in some places solar connections aren't even allowed. So long as solar is a small fraction of the total power it has basically zero effect on the grid. Now, however, there are a lot of solar setups. Look what happens to the grid: The total delivered power drops, but the peak power (when the cloud passes in front of the sun and all those panels quit working) stays the same. They need to spend just as much on generators as before but they aren't selling as much power. Historically, the cost of being able to produce the power has simply been folded into the cost of the power but with the two going out of sync this model no longer applies. Solar gets a substantial hidden subsidy from this, without this subsidy solar is almost never economic. Second, look at what happens when *lots* of homes go solar. Lets say the local substation is delivering 1000A of power to it's area. Lots of panels go up, the combined power is 1500A. Now the substation transformer is being asked to push 500A back up to the distribution wires--and it's probably not built to survive that. Either those substations must be upgraded or the power company simply prohibits the situation from arising the in the first place by not allowing too much solar on any given segment.
  - namibj 5y ago
    1) we here in Germany, for non-standard connections (including using the grid as backup for local generation), have split price between max-power-reached-in-any-15min-rolling-average, and per-kWh. The former is low-medium single-digits per kW and year, depending on whether you hook up to the 6kV (to neutral; low-voltage would be 240V) medium voltage or they have to keep a 6kV->240V 3-phase transformer ready for you. At 20-30ct/kWh, this sums up to (assuming low-voltage) 0.3% duty cycle getting you to spend as much on energy as you spend on power/capability. As for the substation: it doesn't care beyond possibly having to switch some taps that are used to correct for load-current-dependant voltage drop in that 6kV network, but I doubt they get anywhere near their delivered voltage limits in normal operation, anyways.

toast0 5y ago

Grid tied home solar is usually about economics (and sometimes happy feelings), not reliability. If you want automatic transfer, you need to add storage, and a more complex inverter that can operate in bridge tied and island mode, and that cuts into the economics. You might also need to get more panels to handle projected loads during projected outages, but most net metering tarrifs I've seen won't compensate you if you over generate.

jacquesm 5y ago
I can assure you that reliability factors in heavily in Grid tied home solar.
- Symbiote 5y ago
  That must depend on the area. People in the Netherlands or the UK have reliable power anyway, but there are still some home solar installations.
- _ea1k 5y ago
  That varies greatly. In my area, the grid is extremely reliable. I rarely see systems that are setup to handle outages as the cost isn't really worth it on its own.
LorenPechtel 5y ago
This. Normal solar relies on the grid as it's "storage". The economics of solar become very different if you have to provide local storage. This is also why there is an ongoing fight over net metering and in some places solar connections aren't even allowed. So long as solar is a small fraction of the total power it has basically zero effect on the grid. Now, however, there are a lot of solar setups. Look what happens to the grid: The total delivered power drops, but the peak power (when the cloud passes in front of the sun and all those panels quit working) stays the same. They need to spend just as much on generators as before but they aren't selling as much power. Historically, the cost of being able to produce the power has simply been folded into the cost of the power but with the two going out of sync this model no longer applies. Solar gets a substantial hidden subsidy from this, without this subsidy solar is almost never economic. Second, look at what happens when *lots* of homes go solar. Lets say the local substation is delivering 1000A of power to it's area. Lots of panels go up, the combined power is 1500A. Now the substation transformer is being asked to push 500A back up to the distribution wires--and it's probably not built to survive that. Either those substations must be upgraded or the power company simply prohibits the situation from arising the in the first place by not allowing too much solar on any given segment.
- namibj 5y ago
  1) we here in Germany, for non-standard connections (including using the grid as backup for local generation), have split price between max-power-reached-in-any-15min-rolling-average, and per-kWh. The former is low-medium single-digits per kW and year, depending on whether you hook up to the 6kV (to neutral; low-voltage would be 240V) medium voltage or they have to keep a 6kV->240V 3-phase transformer ready for you. At 20-30ct/kWh, this sums up to (assuming low-voltage) 0.3% duty cycle getting you to spend as much on energy as you spend on power/capability. As for the substation: it doesn't care beyond possibly having to switch some taps that are used to correct for load-current-dependant voltage drop in that 6kV network, but I doubt they get anywhere near their delivered voltage limits in normal operation, anyways.