Tesla Powerwall $350 / kwh Retail

[arkmundi]

I'm still reading up. Some nice articles:
http://www.bloomberg.com/news/artic...s-powerwall-event-the-11-most-important-facts
http://www.forbes.com/sites/christo...ll-is-just-another-toy-for-rich-green-people/
http://www.theregister.co.uk/2015/05/04/tesla_powerwall_the_game_change_flavoured_battery/
Its clear that this summer's production starts in the Tesla Model S factory. The "wall-mount" form factor follows that of the Tesla Model S. We must also conclude that Powerwall electronics, management systems, cooling, etc., are also borrowed. For those of us considering using the PowerWall for our LEV's, this is a good thing.

As far as grid-storage is concerned, its yet to be seen. As renewables grow as a slice of grid production, storage becomes proportionally more important. Here in Massachusetts, the mandate is for 25% renewable by 2020, so the need is now. What someone with business savy and money should do is build-out a gigawatt factory on Elon Musk's offer of open-source and expansion, with almost all of that capacity never leaving the site - just building up & up to keep up with the energy storage demand. FYI, Brayton Point, New England's largest coal generation plant, closes in 2017. Our NE-ISO is worried. So was the last Governor. So is the current Governor. They should be.

 

[Ohbse]

I've seen plenty of people dismiss this and point at prices for lead acid batteries and say hey look, I can do it for 50% less. Those people have clearly never dealt with lead acid in mission critical situations or understand TCO. Nor do they understand everything else that's in the box.

Ditto all the above experience with lead acid in UPS form, my god it's no fun. What really gets me is that sometimes the failure mode is unpredictable, the battery monitoring doesn't always see an issue until substantial load is applied. For that reason UPS's do a regular self test and partially discharge the battery bank. Despite this I've had situations where an entire string has failed and actually dropped the load because of a single cell failure that's either not been picked up by self test or has occurred since it was last tested. Very frustrating dealing with the aftermath when the root cause is easily identified, but there's no actual way to mitigate that risk beyond doubling down and having another string, thereby multiplying your chance of experiencing a cell failure, but probably keeping the critical equipment up. It's a slippery slope that ends with a big room full of nasty batteries and a constant headache.

My house might not be 'critical' in the conventional sense, nobody is going to die or lose millions of dollars an hour during an outage, but I will be annoyed. That's worth money.

 

[bikeelectric]

Can anyone explain why these are 350 to 400 volts ? Is that because it is what the cars use for power ?

 

[Hillhater]

Can anyone explain why these are 350 to 400 volts ? Is that because it is what the cars use for power ?

Not necessarily " because" ...but probably for the same reason the cars are 400v....keep the amperage down and efficiency.
If they worked at 110 v, they would be dealing with 3-4 times the current levels for any given charge/discharge rate, and they would need 3-4 times numbers of cells in parallel.
But there is probably some other logic to it also ?

 

[Arlo1]

I think Hill Hater is on the right track. I think there is a few reasons.
1 to feed into a 220v ac grid you will be better off higher then lower voltage.
2 Mosfets work best when voltages are below 200v and IGBTs are the winners above 300v
3 when using IGBTs the higher voltages will help system efficiency but they need to keep it below a safe number for people to not get Zapped
4 When stringing a few solar panels together it will be easier to charge
5 It is likely very close to the car voltage if not the same # of cells in series meaning all the BMS and other designs will be used or borrowed from.

I'm sure we will find out more in time. But you don't want to low of voltages for this stuff.... You also don't want it to high

 

[Punx0r]

Is this issue with failures in UPS batteries due to the large size of the cell? I read with interest about the increased reliability achieved in Li-ion batteries by using multiple smaller cells rather than fewer larger ones being due to the relative ease of making an unflawed small cell and detecting characteristics of flawed ones, allowing them to be rejected. I wonder is a similar situation applies to these huge lead-acid cells?


Also, out of interest, what sort of backup time is expected from these systems? See, my thinking is that it takes maybe 10 seconds to get diesel gensets online and on load...

 

[riba2233]

and they would need 3-4 times numbers of cells in parallel.
But there is probably some other logic to it also ?

Yes, but proportionally less cells in series, so in the end it's the same number of cell.

2 Mosfets work best when voltages are below 200v and IGBTs are the winners above 300v

Are you sure? This might have been correct few years ago. Now we have these:

http://www.cree.com/Power/Products/MOSFETs

 

[Arlo1]

2 Mosfets work best when voltages are below 200v and IGBTs are the winners above 300v

Are you sure? This might have been correct few years ago. Now we have these:

http://www.cree.com/Power/Products/MOSFETs[/quote]
I worked out the math about 2 months ago and the best IGBTs still are better at high voltages then those!

 

[riba2233]

Are you talking about that same package, to247? And at what switching frequency

 

[granolaboy]

Another intersting article I stumbled across:

http://www.bloomberg.com/news/articles/2015-04-14/fossil-fuels-just-lost-the-race-against-renewables

 

[arkmundi]

A remarkable confluence of heroic action on the part of Elon Musk and many others, re-envisioning the future of clean sustainable energy, and a mad technology race with universities and other R&D operations to make the shift, and the PowerWall, GigaWatt factory, etc. coming out in a just-in-time fashion, and... and... its almost enough to make me hope for a future. Alas, for those following the other emerging story - the massive methane releases as the ocean bed clathrate formations nearest the surface melt, along with the Tundra, etc. Nonetheless, the drama of it all is spectacular. Will humanities angels or humanities demons win? Did Christ just reincarnate as Elon Musk. Do I need an altar with his picture and light incense? :lol:

 

[999zip999]

I think you already have. You just have to build it.
I have Pamela Anderson.

 

[999zip999]

What about home wind turbine and solar combo ? Golden West C.C. had a home wind turbine work shop.

 

[JackB]

Billionaire worship, sad state of affairs in America.

 

[arkmundi]

Billionaire worship, sad state of affairs in America.

May dog bless you. Have three hail-mary's, go to a mall and spend more!

 

[Dauntless]

http://www.bloomberg.com/news/articles/2015-05-06/tesla-s-new-battery-doesn-t-work-that-well-with-solar

 

[parabellum]

I have not seen 2kw household vacuum cleaner by now, but 2 kw out of 10kwh pack is not in the tesla car cells region. Why 2 kw output?

 

[Hillhater]

2.5+ Kw vacs are common in Europe and Other 240v country's .

 

[opperpanter]

2.5+ Kw vacs are common in Europe and Other 240v country's .

Not anymore. New vacuum cleaners in EU are not allowed to have 1000w or so.

 

[arkmundi]

 

[Hillhater]

Not anymore. New vacuum cleaners in EU are not allowed to have 1000w or so.

I wonder why the EU dreamed up that law ??
Plenty of them still in other parts of the world though.
....and ref the original comment regarding the Tesla PowerWall 2kW max output... You don't want to know what a decent coffee machine draws, let alone a cook top or water heater (5-7 kW !)
Even a humble basic water kettle can be 3 kW .
Why exactly, would a 7 kWhr battery bank only be capable of 2 kW max discharge ??

 

[striker54]

Why exactly, would a 7 kWhr battery bank only be capable of 2 kW max discharge ??

To the consumer buy more than one and to the cells last all the warranty time without problems.

 

[MitchJi]

Hi,

http://venturebeat.com/2014/08/01/h...uld-change-everything-not-just-electric-cars/

In keeping with Musk’s environmentally sustainable reputation, the facility, which will sit on 500 to 1,000 acres, will not only recycle older battery packs but will also be powered by “new local renewables,” namely wind turbines and photovoltaic panels.

Two different cell chemistries:
http://www.teslamotors.com/powerwall

Models
10 kWh $3,500 For backup applications
7 kWh $3,000 For daily cycle applications
Warranty
10 years

 

[parabellum]

Why exactly, would a 7 kWhr battery bank only be capable of 2 kW max discharge ??

To the consumer buy more than one and to the cells last all the warranty time without problems.

Those batteries are reported to sustain 3C discharge, so at 1C it probably overlives the waranty by far, 0.3-0.2C is....

 

[MitchJi]

Hi,

http://rameznaam.com/2015/04/14/energy-storage-about-to-get-big-and-cheap/#Grid

C. Storage as a Grid Component (Caching for Electrons)

Both of the previous scenarios have looked at this from the standpoint of installation in homes (or businesses – the same logic applies).

But the dropping price of storage isn’t inherently biased towards consumers. Utility operators can deploy storage as well, Two recent studies have assessed the economics of just that. And both find it compelling. Today. At the price of batteries that Tesla has announced.

First, Texas utility Oncor commissioned a study (pdf link – The Value of Distributed Electricity Storage in Texas) of whether it would be cost-effective to deploy storage throughout the Texas grid (called ERCOT), placing the energy storage at the ‘edge’ of the grid, close to consumers.

The conclusion was an overwhelming yes. The study authors concluded that, at a capital cost of $350 / kwh for lithium-ion batteries (which they expected by 2020, but which Tesla has already beaten), it made sense across the ERCOT region to deploy at least 15,000 MWh of battery storage. (That would be 15 million KWh, or the equivalent battery capacity of nearly 160,000 Tesla model 85Ds.)

The study authors concluded that this additional battery storage would slightly lower consumer electrical bills, reduce outages, reduce the need to build added capacity (by shifting the peak, much as a home battery would), and similarly reduce the need to build additional transmission and distribution lines.

The values shown above are in megawatts of power, by the way. The assumption is that there are 3 MWh of storage per MW of power output in the storage system.

You can also see that at a slightly lower price of storage than the $350 / kwh assumed here, the economic case for 8,000 MW (or 24,000 MWh) of storage becomes clear. And we are very likely about to see such prices.

8,000 MW or 8 GW is a very substantial amount of energy storage. For context, average US electrical draw (over day/night, 365 days a year) is roughly 400 GW. So this study is claiming that in Texas alone, the economic case for energy storage is strong enough to motivate storage capacity equivalent to 2% of the US’s average power draw.

ERCOT consumes roughly 1/11th of the US’s electricity. (ERCOT uses roughly 331,000 GWh / year. The US as a whole roughly 3.7 million GWh / year.) If similar findings hold true in other grids (unknown as of yet), that would imply an economic case fairly soon for energy storage capacity of 22% of US electric draw for 3 hours, meaning roughly 88,000 MW or 264,000 MWh.

This is, of course, speculative. We don’t know if the study findings scale to the whole of the United States. It’s back of the envelope math. Atop that, the study itself is an analysis, which is not the same value as experience. Undoubtedly in deployment we’ll discover new things which will inform future views. Even so, it appears that there is very real value at unexpectedly high prices.

Energy storage, because of its flexibility, and because it can sit in so many different places in the grid, doesn’t have to compete with wholesale grid power prices. It competes with the price of peak demand power, the price of outages, and the price of building new distribution and transmission lines.

Which brings us to scenario 2D:
D. Replacing Natural Gas Peakers
The grid has to be built out to support the peak of use, not the average of use. Part of that peak is sheer load. Earlier I mentioned natural gas ‘peaker’ plants. Peaker plants are reserve natural gas plants. On average they’re active far less than 10% of the time. They sit idle, fueled, ready to come online to respond to peaking electricity demand. Even in this state, bringing a peaker online takes a few minutes.

Peaker plants are expensive. They operate very little of the time, so their construction costs are amortized over few kwh; They require constant maintenance to be sure they’re ready to go; and they’re less efficient than combined cycle natural gas plants, burning roughly 1.5x as much fuel per kwh of electricity delivered, since the economics of investing in their efficiency hardly make sense when they run for so little of the time.

The net result is that energy storage appears on the verge of undercutting peaker plants. You can find multiple articles online on this topic. Let me point you to one in-depth report, by the Electric Power Research Institute (EPRI): Cost-Effectiveness of Energy Storage in California (pdf).

This report specifically looked at the viability of replacing some of California’s natural gas peaker plans.

While the EPRI California study was asking a different question than the ERCOT study that looked at storage at the edge, it came to a similar conclusion. Storage would cost money, but the economic benefit to the grid of replacing natural gas peaker plants with battery storage was greater than the cost. Shockingly, this was true even when they used fairly high prices. The default assumption here was a 2020 lithium-ion battery price of $528 / kwh. The breakeven price their analysis found was $842 / kwh, three times as high as Tesla’s announced utility scale price of $250/kwh.