5 ms·

Quick math shows a long range Model 3 has about six times as much battery capacity as a Powerwall. I’m willing to bet more people have Model 3’s than Powerwalls

Quick math shows a long range Model 3 has about six times as much battery capacity as a Powerwall. I’m willing to bet more people have Model 3’s than Powerwalls. And I’m willing to bet 16% of your car’s battery capacity will impact you far less than 100% of your Powerwall. F-150 Lightning called it right: EV’s should ship with grid-tie inverting.

jfim 4y ago
It's pretty interesting if you do the math too. The CAISO shows that their current power generation capacity is about 53000 MW. A Tesla model 3 has 60kWh of capacity. A million of those would allow generating 60000 MW for an hour if they would be discharged from full to empty during the span of that hour. In practice, they wouldn't be able to be discharged that quickly and there would be losses due to going from DC to AC, but it's interesting to think that the total deployed battery capacity of EVs could have a significant impact on the need for peaker plants in the upcoming years.
- tsimionescu 4y ago
  And how exactly would you use your car if you discharge it overnight?
  - jillesvangurp 4y ago
    You wouldn't fully discharge it. The car has way more power than your house needs in a single night. You could probably run your house for a few days, even if your house has the AC on full, is huge, and poorly insulated. In which case you'd have a huge incentive to do something about your grid electricity cost. Installing solar panels and batteries is a way to do that. Driving an EV makes total sense if you have those. And adding that battery capacity to the mix makes even more sense. You'd use an app to control how much power you allow to be taken and when. Mainly grids have peaks in the early evening and excess wind power during the night and excess solar power during the day. It's as much as being able to absorb that excess power than it is about providing power during peak hours.
  - drusepth 4y ago
    As I understand it, this program starts discharging at 6pm. Off-hours power is almost always cheaper, so I imagine you could discharge in the evening/night and buy back whatever you needed from the grid in the cheaper hours of the night/morning for a profit.
  - jfim 4y ago
    The idea is not to fully discharge it overnight, but to smooth out demand. During the daytime, solar power is plentiful, but not during the evening. However, during the evening, there is demand from residential customers so that they can cook, watch TV, use their computers, and whatever else people do in the evening that uses electricity. Because there needs to be as much energy supply as there is demand, peaker plants (coal or gas typically) run during the evening to compensate for the fact that solar generation isn't available in the evening. There is less demand for power overnight though, since most people are sleeping. As such, what would make sense would be that people would recharge their cars during daytime, drive back home, connect their cars to the grid and have them contribute some percentage of their battery to lower the need for peaker plants in the evening, then charge to full overnight.
mtgx 4y ago
mlindner 4y ago
People don't seem to understand that the battery chemistries optimized for cars is not the same battery chemistries optimized for grid storage though. You'll reduce the lifetime of your car substantially by cycling it every night.
- speedgoose 4y ago
  You are downvoted but you are right. A Tesla model 3 battery is not designed to balance the electricity grid. Maybe it can be done in the future by using different chemistry, with some downsides, but the current cars would get destroyed by the many cycles.
- traviswt 4y ago
  Any usage will reduce a battery’s lifespan, but this isn’t a donation. The point of enrolling in a sharing program is you get compensated for letting the utility company use your resources. It should much more than offset the extra degradation. Degradation of lithium batteries is also not constant. It depends on several factors such as C rate, heat, and voltage. All of these factors would be far less during load sharing than just driving your car. And keep in mind most people wouldn’t want to share their entire batteries. They would want to save most for themselves. If they only offered 10% of their capacity for load sharing, then the shared usage would be far less than a full cycle.
jillesvangurp 4y ago
The back of the envelope math is beautiful here. EV production is really ramping up now. Tesla expects to put out around 2 million cars per year by the end of the year. If we round the kwh of their batteries down a little to 50kwh, we get some nice round number to work with. 2 million cars is 2 x1000 x 1000 times 50 kwh is 100 gwh. So Tesla alone is adding 100gwh of battery per year (well a bit more but you get my point). Other manufacturers are also producing cars. and we'll soon hit 20 million EVS per year. Or about 1 twh / year of battery production. Those batteries have long lives in the car and then typically a second life in storage solutions. Some cars now come with vehicle to grid technology and when they are plugged in, they could be used to provide power to the home, or the grid. So we have a fleet of car batteries that is currently growing by the hundreds of gwh per year and soon twh per year that can be plugged into the grid. Even just using a tiny amount of that represents an enormous amount of power. That's a huge buffer to dump excess power in during the day (from e.g. solar panels) and withdraw from during peak hours. The current Tesla virtual power plant is tiny in comparison. If you then consider that batteries have a fixed number of cycle times (around 1500 or so), you basically get to pwh scale in terms of amounts of energy that flow through that buffer every year. A lot of that power is cheap renewable power. Just with car batteries. Other storage solutions are available. The world currently produces a bit over 25 pwh per year currently.
- marvin 4y ago
  I've been wondering why Tesla doesn't just do this. IIRC from the public Model 3 and Y teardowns, the cars already have the hardware to do this, so it's just a question of a software update and policy. Would love to know why it isn't in production yet; it seems like a no-brainer so there must be something impeding it.
  - panick21_ 4y ago
    I don't think they have the hardware to do it. And I think the house themselves would also need extra hardware and integration, and its also different from state to state and country to country as far as I understand. But I don't know the details.
  - 4y ago
bertil 4y ago
I’m not sure that you can rely on cars being plugged in as much as Power Walls. If things go bad, it’s very tempting to disconnect your car.

jfim 4y ago

It's pretty interesting if you do the math too. The CAISO shows that their current power generation capacity is about 53000 MW. A Tesla model 3 has 60kWh of capacity. A million of those would allow generating 60000 MW for an hour if they would be discharged from full to empty during the span of that hour. In practice, they wouldn't be able to be discharged that quickly and there would be losses due to going from DC to AC, but it's interesting to think that the total deployed battery capacity of EVs could have a significant impact on the need for peaker plants in the upcoming years.

tsimionescu 4y ago
And how exactly would you use your car if you discharge it overnight?
- jillesvangurp 4y ago
  You wouldn't fully discharge it. The car has way more power than your house needs in a single night. You could probably run your house for a few days, even if your house has the AC on full, is huge, and poorly insulated. In which case you'd have a huge incentive to do something about your grid electricity cost. Installing solar panels and batteries is a way to do that. Driving an EV makes total sense if you have those. And adding that battery capacity to the mix makes even more sense. You'd use an app to control how much power you allow to be taken and when. Mainly grids have peaks in the early evening and excess wind power during the night and excess solar power during the day. It's as much as being able to absorb that excess power than it is about providing power during peak hours.
- drusepth 4y ago
  As I understand it, this program starts discharging at 6pm. Off-hours power is almost always cheaper, so I imagine you could discharge in the evening/night and buy back whatever you needed from the grid in the cheaper hours of the night/morning for a profit.
- jfim 4y ago
  The idea is not to fully discharge it overnight, but to smooth out demand. During the daytime, solar power is plentiful, but not during the evening. However, during the evening, there is demand from residential customers so that they can cook, watch TV, use their computers, and whatever else people do in the evening that uses electricity. Because there needs to be as much energy supply as there is demand, peaker plants (coal or gas typically) run during the evening to compensate for the fact that solar generation isn't available in the evening. There is less demand for power overnight though, since most people are sleeping. As such, what would make sense would be that people would recharge their cars during daytime, drive back home, connect their cars to the grid and have them contribute some percentage of their battery to lower the need for peaker plants in the evening, then charge to full overnight.

mtgx 4y ago

mlindner 4y ago

People don't seem to understand that the battery chemistries optimized for cars is not the same battery chemistries optimized for grid storage though. You'll reduce the lifetime of your car substantially by cycling it every night.

speedgoose 4y ago
You are downvoted but you are right. A Tesla model 3 battery is not designed to balance the electricity grid. Maybe it can be done in the future by using different chemistry, with some downsides, but the current cars would get destroyed by the many cycles.
traviswt 4y ago
Any usage will reduce a battery’s lifespan, but this isn’t a donation. The point of enrolling in a sharing program is you get compensated for letting the utility company use your resources. It should much more than offset the extra degradation. Degradation of lithium batteries is also not constant. It depends on several factors such as C rate, heat, and voltage. All of these factors would be far less during load sharing than just driving your car. And keep in mind most people wouldn’t want to share their entire batteries. They would want to save most for themselves. If they only offered 10% of their capacity for load sharing, then the shared usage would be far less than a full cycle.

jillesvangurp 4y ago

The back of the envelope math is beautiful here. EV production is really ramping up now. Tesla expects to put out around 2 million cars per year by the end of the year. If we round the kwh of their batteries down a little to 50kwh, we get some nice round number to work with. 2 million cars is 2 x1000 x 1000 times 50 kwh is 100 gwh. So Tesla alone is adding 100gwh of battery per year (well a bit more but you get my point). Other manufacturers are also producing cars. and we'll soon hit 20 million EVS per year. Or about 1 twh / year of battery production. Those batteries have long lives in the car and then typically a second life in storage solutions. Some cars now come with vehicle to grid technology and when they are plugged in, they could be used to provide power to the home, or the grid. So we have a fleet of car batteries that is currently growing by the hundreds of gwh per year and soon twh per year that can be plugged into the grid. Even just using a tiny amount of that represents an enormous amount of power. That's a huge buffer to dump excess power in during the day (from e.g. solar panels) and withdraw from during peak hours. The current Tesla virtual power plant is tiny in comparison. If you then consider that batteries have a fixed number of cycle times (around 1500 or so), you basically get to pwh scale in terms of amounts of energy that flow through that buffer every year. A lot of that power is cheap renewable power. Just with car batteries. Other storage solutions are available. The world currently produces a bit over 25 pwh per year currently.

marvin 4y ago
I've been wondering why Tesla doesn't just do this. IIRC from the public Model 3 and Y teardowns, the cars already have the hardware to do this, so it's just a question of a software update and policy. Would love to know why it isn't in production yet; it seems like a no-brainer so there must be something impeding it.
- panick21_ 4y ago
  I don't think they have the hardware to do it. And I think the house themselves would also need extra hardware and integration, and its also different from state to state and country to country as far as I understand. But I don't know the details.
- 4y ago

bertil 4y ago

I’m not sure that you can rely on cars being plugged in as much as Power Walls. If things go bad, it’s very tempting to disconnect your car.