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Tesla Powerwall

Posted: Fri May 01, 2015 3:49 am
by LTLFTcomposite
http://www.cnbc.com/id/102637763" onclick="window.open(this.href);return false;

The pricing is attractive. Not sure how this helps with EVs though; you'd still be reliant on buying off peak power for charging.

Re: Tesla Powerwall

Posted: Fri May 01, 2015 4:32 am
by LTLFTcomposite
This doesn't look nearly as cool as first thought, the specs say it doesn't include an inverter. I was hoping for a "just add solar panels" solution.

Re: Tesla Powerwall

Posted: Fri May 01, 2015 8:43 am
by AndyH
LTLFTcomposite wrote:This doesn't look nearly as cool as first thought, the specs say it doesn't include an inverter. I was hoping for a "just add solar panels" solution.
No, it's not a complete solution as is and that's not unexpected. An off-grid building needs two bits of electronics - a battery charger that interfaces the PV panels to the battery, and an inverter that sits between the battery and the house's 120V and possibly 240VAC grid. The vast majority of people with grid-tied PV have an interface between the PV and power grid that only works when the sun's shining and cannot work with a battery - so there's no load-shifting or backup power.

I'm interested in learning the retail price for one of these boxes. The wholesale price for a complete unit is less expensive than the retail price for a box of LiFePO4 cells of similar capacity...and the LiFePO4 still needs interconnects, management, and won't have web management or smart grid interoperability.

Re: Tesla Powerwall

Posted: Fri May 01, 2015 8:48 am
by LTLFTcomposite
Supposedly $3500 for 10 kwh

Re: Tesla Powerwall

Posted: Fri May 01, 2015 8:53 am
by BrockWI
For home installations I can't imagine it competing with lead acid for cost per watt. We have 18 kwh of lead acid that was $1800, its not that large of floor space, but weighs a couple of tons, but it does require some periodic maintenance, I miss our AGM's :)

I do wonder if someone like Schneider (Xantrex) will come up with a grid tie inverter with these batteries in mind, a plug and play setup. Then you could have a grid tie inverter system and then if you choose to add these you now have grid tie with backup and load shifting or peak shaving potential.

Re: Tesla Powerwall

Posted: Fri May 01, 2015 9:00 am
by AndyH
LTLFTcomposite wrote:Supposedly $3500 for 10 kwh
I thought I heard Elon say the $3500 was for 'installers' and assumed wholesale. I see on the Powerwall site, though, that it's listed as $3500 without qualifiers.

http://www.teslamotors.com/powerwall

I got a chuckle out of this:
Both are guaranteed for ten years and are sufficient to power most homes during peak evening hours
The 10kWh model will run an efficient off-grid house for 2.3 days...

Re: Tesla Powerwall

Posted: Fri May 01, 2015 9:08 am
by LKK
I'm interested. A single 10 KWH battery would work for me as a home backup power source, but the key for me is the ability to recharge it from my solar system when the grid is down. Since I have a grid tied system I would need a transfer capability to switch from the grid to the battery when the grid is down. In order to make my inverters work, the battery will also have to fool the inverters into thinking they are still tied to the grid by supplying a 240 VAC, 60 Hertz waveform to synchronize with.

Anyone know if this battery can do this?

Re: Tesla Powerwall

Posted: Fri May 01, 2015 9:26 am
by edatoakrun
Sounds like they probably are using the same battery design they do in the S:
...The packs contain all the integrated safety systems, the liquid thermal control...
http://www.greencarcongress.com/2015/05 ... tesla.html" onclick="window.open(this.href);return false;

IMO, LTC/ATM is generally a bad idea for BEVs, and perhaps even more of a disadvantage in small-scale stationary installations.

The prices are pretty cheap per unit, but remember, the vast majority of buyers will need to install multiple units in their installations, to power conventional high-kWh demand homes when the sun isn't out, or when the grid is down.

An S owner who buys ~10 of these so they can do a mid-day Summer recharge with off-peak kWh, is going to have one hot garage...

Re: Tesla Powerwall

Posted: Fri May 01, 2015 9:29 am
by TimLee
$350 per kWh is the real news.
Beats the few competitors out there by quite a bit.

Does pretty clearly show that Nissan's $250 per kWh replacement heat resistant pack with trade-in is at least somewhat below production cost.

Yes, lead acid is cheaper.
But only a small part of the real world limited market for home energy storage is willing to put up with the space and maintenance requirements of lead acid.

Powerwall seems pretty incomplete without inverter system readily available that automatically switches between on grid and off grid.
Maybe Tesla is using the "build it and they will come" approach :?:

Does Power wall have a temperature control system :?:
Is it OK to use it in your 120F garage in Phoenix :?:
Or even your Chattanooga garage that sometimes hits 105F :?:

Re: Tesla Powerwall

Posted: Fri May 01, 2015 9:37 am
by AndyH
edatoakrun wrote:Sounds like they probably are using the same battery design they do in the S:
...The packs contain all the integrated safety systems, the liquid thermal control...
http://www.greencarcongress.com/2015/05 ... tesla.html" onclick="window.open(this.href);return false;

IMO, LTC/ATM is generally a bad idea for BEVs, and perhaps even more of a disadvantage in small-scale stationary installations.

The prices are pretty cheap per unit, but remember, the vast majority of buyers will need to install multiple units in their installations, to power conventional high-kWh demand homes when the sun isn't out, or when the grid is down.

An S owner who buys ~10 of these so they can do a mid-day Summer recharge with off-peak kWh, is going to have one hot garage...
It wouldn't make good business sense to not use the same battery design. Why do you think that liquid thermal management is a bad idea for BEVs and 'home' use? Musk says the box can be attached to an outside wall...Having lived in Tucson, I know those outside walls can be really toasty...and my San Antonio garage stays above 100°F for more than 3 months each summer...before adding any additional heat...