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LTLFTcomposite
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Re: Tesla Powerwall

Sat May 02, 2015 6:03 am

15 SEER central air is supposedly 800w/ton, and that's running, not starting. So this won't work for even a modest home in a warmer climate if the goal is to zero out the grid usage.
LTL
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TimLee
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Re: Tesla Powerwall

Sat May 02, 2015 6:12 am

The video on the Bloomberg article on the Solar City pricing provides perspective that it isn't really for individuals and homes.
The potential real demand for it is businesses and utilities shifting some of their use off peak.
http://www.bloomberg.com/news/articles/ ... g-at-5-000" onclick="window.open(this.href);return false;

Tim Lee
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Slow1
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Re: Tesla Powerwall

Sat May 02, 2015 6:15 am

LTLFTcomposite wrote:15 SEER central air is supposedly 800w/ton, and that's running, not starting. So this won't work for even a modest home in a warmer climate if the goal is to zero out the grid usage.
I wonder if the max output scales with additional units - i.e. 2Kw for one 4Kw for two? Depends on how they are connected I suppose...

In any case if you assume remaining grid-tied then you can pull those peak loads off the grid and simply time shift whatever capacity you have. Still a potentially useful product I'm sure - fully off-grid is another story as you need several days supply etc, just not something most of us can justify from a cost perspective eh?
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RegGuheert
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Re: Tesla Powerwall

Sat May 02, 2015 6:36 am

TimLee wrote:The video on the Bloomberg article on the Solar City pricing provides perspective that it isn't really for individuals and homes.
The potential real demand for it is businesses and utilities shifting some of their use off peak.
http://www.bloomberg.com/news/articles/ ... g-at-5-000" onclick="window.open(this.href);return false;
TOU shifting is certainly desirable. So the question is why does Elon Musk or anyone else think that Li-ion batteries are the right solution for this application (for utility-scale applications)? Perhaps it is, but then why does this unit not include a 480VAC inverter to make it a true three-phase AC battery? Businesses are benefiting today from new PV technology which does power-factor correction (and I believe some of those solutions even work at night), but PV pays for itself even without this feature.

Just to put things into perspective, here is the list of "they suck!" characteristics from Elon Musk's speech:

- Expensive
- Unreliable
- Poor integration
- Poor lifetime
- Low efficiency
- Not scalable
- Unattractive (I guess that means they do not come in pretty colors. ;) )

But, seriously, does Li-ion REALLY come out on top for large-scale grid applications? I think there are other solutions which are more likely win out for stationary applications. Perhaps Tesla Energy can slot in somewhere between the homeowner and factories and address the needs of small businesses.
RegGuheert
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SmartElectric

Re: Tesla Powerwall

Sat May 02, 2015 6:42 am

Slow1 wrote: I wonder if the max output scales with additional units - i.e. 2Kw for one 4Kw for two?
It does. Read about it.
http://www.teslamotors.com/powerwall" onclick="window.open(this.href);return false;

Can be combined up to 9 modules, 2x9=18kW of output power and 7x9=63kWh of storage

TimLee
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Re: Tesla Powerwall

Sat May 02, 2015 7:19 am

SmartElectric wrote:...
Can be combined up to 9 modules, 2x9=18kW of output power and 7x9=63kWh of storage
Better, but still maximum of 75 amps 240V service.
Will definitely need to be a very efficient net zero home to be off grid with that.
Plus it is $63,900 of equipment from Solar City plus maintenance cost.
Or $45,000 up front with nine year lease and maintenance is included.
Pretty costly to be off grid :o

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evnow
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Re: Tesla Powerwall

Sat May 02, 2015 9:08 am

Slow1 wrote:In any case if you assume remaining grid-tied then you can pull those peak loads off the grid and simply time shift whatever capacity you have. Still a potentially useful product I'm sure - fully off-grid is another story as you need several days supply etc, just not something most of us can justify from a cost perspective eh?
As a backup - one would need the ability to run the fridge, some lights, range, the heater / AC ... most "whole house" generators start around 10 kW.
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JimSouCal
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Re: Tesla Powerwall [Cost Advantage?]

Sat May 02, 2015 9:37 am

RegGuheert wrote:Frankly, I think Enphase is more on track with their AC Battery. It's small enough and cheap enough for people to experiment with it while still being scalable to large applications.
I remember it being announced. Is the Enphase AC battery out for sale in the marketplace and considered back behind leading bleeding edge? I am game to try..

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JimSouCal
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Re: Tesla Powerwall

Sat May 02, 2015 9:46 am

Some vaguely OT things about Elon Musk. His house in Belair is no small potatoes... Recently Musk had several full grown large trees flown in by helicopter for landscaping purposes on his hillside, with the nearby neighbors relocated and lots of commotion. The hilly area he lives has aging electrical infrastructure that is very overloaded because folks now have large service loads with 10,000 - 40,000 square foot house. The power goes out enough (a few times a year) to have a standby generator company do a mass mailing. The high dollar niche financials here don't align with the rest of the human realm.

That said, his vision coupled with the efficacy of power and capital is impressive. He has a good idea and can get traction right away. Good luck to him on these ventures I say and wishes of continued success.

Meanwhile, even more off topic, we have LADWP that is openly encouraging solar FIT (feed in tariff) but somehow nothing gets installed. When I visited the Downtown DWP headquarters, the number of high end Mercedes parked in the employee parking was notable...

Distributed energy generation is the future if there is one, but some feeding troughs will have to be tipped over for this to happen. Musk and his plans, a part of that, maybe...

Status normal in Los Angeles....

DanDietrich
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Re: Tesla Powerwall

Sat May 02, 2015 10:38 am

There are a bunch of angles to this. I have a 9kw grid tied solar array and a Leaf. I never lost power during Irene or Sandy, when much of my town was out, so I don't need the complexity of a transfer switch and battery for power. Here in NJ if I want a time of use meter, I get to pay $11.75 per month for the privilege, and our rates would be, I think, 11 cents and 18 cents, so I wouldn't even get back the service charge in savings. I use enphase microinverters on my system, and the tech sheet for the Tesla battery shows a 94% efficiency, so converting my ac to dc and back again costs me another 6% of my power if I use the battery.
I'm all for this stuff, and I don't mind that Tesla gets all of the attention while Nissan sells more electric cars, but this unit isn't really practical or cost effective in many situations. No one in this thread yet had mentioned the power loss due to conversion, and I think that is fairly important to keep in mind as a recurring expense.

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