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.
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.
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.
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.
Doesn't Telsa already sell a product like that?
Re:Tesla Energy
by parasubvert on Friday May 01, 2015 @07:12PM
(#9475094)
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-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.
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.