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1) You don't need this if you have solar. Most states and utilities have pretty favorable subsidies for "selling back" energy to the grid. The utility is credit

1) You don't need this if you have solar. Most states and utilities have pretty favorable subsidies for "selling back" energy to the grid. The utility is credit the feeding back to the grid at 100%. This device will introduce efficiency losses and it is expensive. Unless you have extreme peak v. non-peak fees, I doubt this will save you money. Even at 20 cent difference, 7kW hours is a 1.40 a day. But that assumes that you could use all 7kW hours at peak times (you probably aren't). Also, you'll lose 10% going form AC-DC, you'll lose 8% on the battery, and you lose 10% going from DC-AC. That is about 25% loss. 2) If lots of people get them, the peak v. non-peak difference will collapse.

billions 12y ago
I see this product targeted at current tesla owners. A PowerWall driven supercharger in-house could reduce charge times by 80%. Today's 10 hour charge time is a huge inconvenience compared to a 10 minute gas station run.
- rhino369 12y ago
  Doesn't Telsa already sell a product like that?
  - parasubvert 12y ago
    The home charger cable is capable of 240V/80A (20 kWh) connections. Superchargers are around 363V/225A (90 kWh) but supposedly capable of 120 kWh. http://www.autoblog.com/2013/02/01/hands-on-with-the-tesla-supercharger-video/ http://www.autoblog.com/2013/02/01/hands-on-with-the-tesla-s... So you're looking at 3 hours at home vs 45 minutes at a supercharger for a full charge. With the 10 kWh wall charger you might be able to cut 45 min off a home charge.
    - create123 12y ago
      Not possible. The specs on their site say 2.0kW continuous and 3.3 peak power per power wall.
Hengjie 12y ago
I tend to disagree that the subsidies make sense. In New Zealand, the sell back price recently was reduced in half. The problem is that the price is effectively set by the electricity supplier, which means it's not exactly competitive to sell back. It's gotten to the point where the ROI calculations from this reduction has affected the feasibility of installing solar panels in NZ.
toddh 12y ago
In our area (the bay area), you can't have battery storage and have a grid connection. So in the setup you describe when the power goes out we couldn't run our house on solar energy. We would have to wait for the grid to come back up. It's crazy. That means batteries would be necessary. But we don't have a battery room or room for one. So this is the perfect solution. Will it save money? Tier 4 pricing with PG&E is 34 cents per kwh and the rates are going up. In the summer it's quite easy to hit tier 4.
tcbawo 12y ago
Smoothing out peak/non-peak demand has an enormous economic and ecological benefit. Power plants don't turn on a dime. We often overproduce to handle the peaks.

billions 12y ago

I see this product targeted at current tesla owners. A PowerWall driven supercharger in-house could reduce charge times by 80%. Today's 10 hour charge time is a huge inconvenience compared to a 10 minute gas station run.

rhino369 12y ago
Doesn't Telsa already sell a product like that?
- parasubvert 12y ago
  The home charger cable is capable of 240V/80A (20 kWh) connections. Superchargers are around 363V/225A (90 kWh) but supposedly capable of 120 kWh. http://www.autoblog.com/2013/02/01/hands-on-with-the-tesla-supercharger-video/ http://www.autoblog.com/2013/02/01/hands-on-with-the-tesla-s... So you're looking at 3 hours at home vs 45 minutes at a supercharger for a full charge. With the 10 kWh wall charger you might be able to cut 45 min off a home charge.
  - create123 12y ago
    Not possible. The specs on their site say 2.0kW continuous and 3.3 peak power per power wall.

Hengjie 12y ago

I tend to disagree that the subsidies make sense. In New Zealand, the sell back price recently was reduced in half. The problem is that the price is effectively set by the electricity supplier, which means it's not exactly competitive to sell back. It's gotten to the point where the ROI calculations from this reduction has affected the feasibility of installing solar panels in NZ.

toddh 12y ago

In our area (the bay area), you can't have battery storage and have a grid connection. So in the setup you describe when the power goes out we couldn't run our house on solar energy. We would have to wait for the grid to come back up. It's crazy. That means batteries would be necessary. But we don't have a battery room or room for one. So this is the perfect solution. Will it save money? Tier 4 pricing with PG&E is 34 cents per kwh and the rates are going up. In the summer it's quite easy to hit tier 4.

tcbawo 12y ago

Smoothing out peak/non-peak demand has an enormous economic and ecological benefit. Power plants don't turn on a dime. We often overproduce to handle the peaks.