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So there's going to be a version of the power wall that CANNOT work without the grid? Not even as backup?

I think "off grid" means NO connection to the grid. Think remote mountain cabin or island home.

The 10 kWh Powerwall works when the grid is down, that is its purpose. However it's 1200 cycle NCA chemistry doesn't have the cycle life for off grid use. Tesla makes the 7 kWh "daily cycle" Powerwall for off grid applications. It has NCM chemistry and will last 5000 cycles.

GSP
 
Interesting. What is your source for that assertion?

I should have said "available in the U.S." Solaredge said a few weeks ago they would have the 10kWh available this year. Fronius could be more advanced, as they have their own battery in addition to the powerwall. So Fronius may be ready this year to do the 7kWh powerwall in Europe.


I think "off grid" means NO connection to the grid. Think remote mountain cabin or island home.

The 10 kWh Powerwall works when the grid is down, that is its purpose. However it's 1200 cycle NCA chemistry doesn't have the cycle life for off grid use. Tesla makes the 7 kWh "daily cycle" Powerwall for off grid applications. It has NCM chemistry and will last 5000 cycles.


GSP

Off grid also means capable of being charged from a generator. The 7kWh for off grid will need an AC charge controller, as well as a generator start signal from the inverter. At the time of the powerwall announcement, solaredge/solarcity said they would have off grid for Hawaii available in 2016. So figure 2017.

It is going to be a couple of years before all the bugs are worked out and the battery/inverter hardware is shipping in volume. I've said several times that IMO powerwall pricing is gigafactory pricing. Not much of anything is happening with the powerwall in 2015 except getting people excited.

The 10kWh powerwall is a simple system. Using the 7kWh powerwall is more complicated than it appears at first glance.
 
I understand that difference between 'off-grid' and 'back-up' use...

What I can't for the life of me figure out is how this;

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works if there is a grid failure... do you have to install some kind of ATS? The way this diagram is drawn your battery pack is as useless as your PV array if the grid fails...

I understand that the primary benefit and reasoning behind the power wall is to use solar as much as possible but it seems like most people would expect to be able to use a battery based PV system in the event of a power outage...
 
It is looking more and more like the Powerwall announcement was half baked. While they had some sort of agreement with two inverter manufacturers, neither one had a product even to a detailed a enough stage to actually show customers how they work with a Powerwall. Tesla and Solarcity weren't even on the same page post announcement.
 
However it's 1200 cycle NCA chemistry doesn't have the cycle life for off grid use.

Are NCA batteries okay sitting at 100% SOC for long periods of time? Presumably, the 10kWh PowerWall being used for backup will be sitting at a high SOC for most of it's life. It has to be ready when needed, right? Or, will the software charge it to 80% and then use it as a buffer for the solar array during an outage?

I have been wondering this but never got around to asking the question.
 
Are NCA batteries okay sitting at 100% SOC for long periods of time? Presumably, the 10kWh PowerWall being used for backup will be sitting at a high SOC for most of it's life. It has to be ready when needed, right? Or, will the software charge it to 80% and then use it as a buffer for the solar array during an outage?

I have been wondering this but never got around to asking the question.

The 10kWh powerwall has been specially formulated to sit at 100% SOC and have <5 (?) cycles per month. The full warranty is the best indicator of what the manufacturer really believes. Warranties on batteries are not primarily about repairs, but are a statement of useful life.
I doubt Tesla can get away with an ambiguous storage battery warranty as they have with cars. But they will try :)
 
I understand that difference between 'off-grid' and 'back-up' use...

What I can't for the life of me figure out is how this;

View attachment 86349

works if there is a grid failure...

grid failure doesn't matter in this scenario since the pic you posted is OFF GRID. there is no grid-tie in here. you'd be 100% off grid and no need for paying anything to an electrical provider at all. The grid can fail all day long and it will never affect you here since you aren't connected to it.
 
Interesting. What is your source at Tesla that supports that statement?
I suspect that the 10kWg PowerWall does not sit at 100% SOC but I do not know if that is correct or not.

My source is one of the hundreds of daily solarcity press releases.

I think the actual physical capacity of both powerwalls will be interesting too.
 
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grid failure doesn't matter in this scenario since the pic you posted is OFF GRID. there is no grid-tie in here. you'd be 100% off grid and no need for paying anything to an electrical provider at all. The grid can fail all day long and it will never affect you here since you aren't connected to it.

The inverter referenced in that diagram is UL1741 and CANNOT independently operate off-grid. To my knowledge there currently exists no inverter that can accept the ~350vdc of the Tesla Powerwall AND operate off-grid... EVERY off-grid inverter I know of is 48vdc and MUST use a charge controller. They cannot be tied directly to a PV array.
 
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The inverter referenced in that diagram is UL1741 and CANNOT independently operate off-grid. To my knowledge there currently exists no inverter that can accept the ~350vdc of the Tesla Powerwall AND operate off-grid... EVERY off-grid inverter I know of is 48vdc and MUST use a charge controller. They cannot be tied directly to a PV array.

The only adjustment that I would make to the above statement is that it MUST have a charge controller or battery charger. My solar uses enphase inverters tied to the grid and I am using a Outback Radian inverter and charging my batteries using a 48v battery charger. It is not the most efficient arrangement. I do not charge from solar. I use the inverter to power my critical loads during the peak rate period and charge my batteries at the super off peak rate. That way I maximize the amount of solar generation that gets sold to the grid. It is a combination of arbitrage and load shifting. I agree with @nwdriver in that so far that capability has not yet been demonstrated for inverters running at 350v DC.
 
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