5 ms·

They pay $2/kWh. A powerwall can export 7 kW with a capacity it 12.5 kWh so you can make $25 in a little under 2 hours if you let them drain your power wall. P

They pay $2/kWh. A powerwall can export 7 kW with a capacity it 12.5 kWh so you can make $25 in a little under 2 hours if you let them drain your power wall. Prices infrequently get to $2000/MWh so I expect most years the powerwalls would not be called upon at this price level. It is weak that they only pay for energy delivered instead of being available to deliver as reserve, but I am sure that will come once the technical details are ironed out. The downside of this type of tech is that it adds a dependency on the internet for reserve power.

mulmen 4y ago
Seems fine for reserve power but not for emergency power. And in an emergency you don’t want back-feeding anyway. But I’m not an expert on any of this.
xpe 4y ago
> The downside of this type of tech is that it adds a dependency on the internet for reserve power. I haven't researched this yet, but wouldn't a true "smart" grid have wiring for communications as well as power?
- thrtythreeforty 4y ago
  I want to say there's a lot of powerline communication on the grid, but a lot of that infrastructure can't talk through transformers.
  - liketochill 4y ago
    There is power line carrier signal used between substations and generators on a line but expensive high voltage wave traps are required and you get about 14bits of bandwidth. The applications I’ve done if your bit drops out and health is still good then you have to disconnect. Transmission lines often run fiber too, but used to still use a whole fiber to transmit 8 bits, or serial at 9600 baud
    - thrtythreeforty 4y ago
      Ha, that's hilarious. How do you send serial over fiber? Simple on-off keying? Fiber makes a ton of sense. Non conductive and long range. Surely cheap at utility quantities.
- michaelt 4y ago
  Not usually, no. I mean, my home is already served by cable for the telephone company, cable for the TV company, and a choice of several cellular connections. Most 'smart grid' stuff doesn't try to reinvent the wheel.
andreareina 4y ago
> It is weak that they only pay for energy delivered instead of being available to deliver as reserve, but I am sure that will come once the technical details are ironed out. I think the bigger problem is that residential users can't really guarantee supply, so it doesn't work for the utility to contact for that.

mulmen 4y ago

Seems fine for reserve power but not for emergency power. And in an emergency you don’t want back-feeding anyway. But I’m not an expert on any of this.

xpe 4y ago

> The downside of this type of tech is that it adds a dependency on the internet for reserve power. I haven't researched this yet, but wouldn't a true "smart" grid have wiring for communications as well as power?

thrtythreeforty 4y ago
I want to say there's a lot of powerline communication on the grid, but a lot of that infrastructure can't talk through transformers.
- liketochill 4y ago
  There is power line carrier signal used between substations and generators on a line but expensive high voltage wave traps are required and you get about 14bits of bandwidth. The applications I’ve done if your bit drops out and health is still good then you have to disconnect. Transmission lines often run fiber too, but used to still use a whole fiber to transmit 8 bits, or serial at 9600 baud
  - thrtythreeforty 4y ago
    Ha, that's hilarious. How do you send serial over fiber? Simple on-off keying? Fiber makes a ton of sense. Non conductive and long range. Surely cheap at utility quantities.
michaelt 4y ago
Not usually, no. I mean, my home is already served by cable for the telephone company, cable for the TV company, and a choice of several cellular connections. Most 'smart grid' stuff doesn't try to reinvent the wheel.

andreareina 4y ago

> It is weak that they only pay for energy delivered instead of being available to deliver as reserve, but I am sure that will come once the technical details are ironed out. I think the bigger problem is that residential users can't really guarantee supply, so it doesn't work for the utility to contact for that.