What is Tesla Powerwall?

Category: Cool-Stuff

Elon Musk thinks you’ll get a charge out of his latest product: the Tesla Powerwall, a wall-mounted battery that stores up to 10 kiloWatt-hours of electricity. Musk calls it “the missing piece” in the puzzle of how to wean ourselves off dependency on fossil fuels and power grids. Here's what you need to know...

Fire the Utility Company?

The Sun generates all the power humanity needs (which Musk estimates at 90,000 gigaWatt-hours annually). Enough solar panels to supply all of humanity’s needs would take up no more than half of New Jersey. Most of those solar panels would be mounted on existing rooftops and take up no additional acreage at all.

But the Sun does not shine all the time, or even with equal strength all the time. Therefore, electric power generation by solar panels is uneven and often unavailable. We need batteries to store surplus solar electricity until it’s needed. Big batteries aren’t cheap, as anyone who owns a boat or solar-powered home knows. Batteries are bulky and ugly; most homes that have gone off-grid include an entire room just for battery and related gear, or even an outdoor shed.

The Powerwall introduced by Tesla Energy puts everything you need (except a DC/AC inverter) into a relatively stylish package about the size of a 50-inch flat-screen TV. It’s designed to be hung on a wall, even an exterior wall. Up to nine PowerWalls can be “stacked” for additional storage.
Tesla PowerWall

A single Powerwall stores up to 7 kWh or 10 kWh of electricity; prices, excluding installation, are $3,000 and $3,500, respectively. (Costs may be lowered by local subsidies from governments and utility companies.) In 2013, the average U. S. household used about 30 kWh of electricity per day. Power consumption varies widely by region; Louisiana’s average is more than twice that of Hawaii. Household habits also play a role in electricity consumption.

A single Powerwall might well get the average household through the night, unless it’s one of those nights when everyone needs space heaters. Up to 9 Powerwalls may be desirable if you want to go fully off-grid or if lengthy power outages are common in your area.

Figuring the Total Costs

At $350 per kWh, the 10 kWh Powerwall beats the leading competition handily. A January, 2015, report from Moody’s pegs the average cost of batteries at $500 to $600 per kWh https://www.moodys.com/research/Moodys-Despite-falling-battery-costs-consumers-unlikely-to-defect-from--PR_315969. But in addition to the PowerWall, you need a DC/AC inverter, and professional installation of the system, which adds $5000 to $7000 to your total cost.

And that assumes you're feeding the PowerWall from the electric grid, for use as a battery backup during brief power outages, or to take advantage of "price-shifting" in areas where electricity is cheaper at night. If you want to use a PowerWall to go off-grid, you'll need to spend another $20-$30K on a solar system.

Is the Powerwall “just another toy for rich green people,” as Forbes’ Christopher Helman asks? http://www.forbes.com/sites/christopherhelman/2015/05/01/why-teslas-powerwall-is-just-another-toy-for-rich-green-people/ His analysis, which includes the cost of the DC/AC converter needed for home use, and the cost of supplying energy to the PowerWall (it only stores power, it doesn't generate) indicates that it probably doesn't make financial sense, unless you already have a solar panel system large enough to power your home.

But powering homes is not the end of Musk’s ambition. Tesla Energy is also working on the PowerPack, a more cubic battery that will store up to 100 kWh of power. It’s intended for utilities and large users such as Amazon, Walmart, or Google. Of course, Tesla won’t rest until every vehicle in the world runs on batteries.

I suspect many readers have at least experimented with solar power and battery storage systems. Your thoughts on these subjects in general, and the Powerwall, are welcome. Post your comment or question below...

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Most recent comments on "What is Tesla Powerwall?"

Posted by:

14 May 2015

I'm glad you included (towards the end) Forbes’ Christopher Helman's mention of another exclusion (you should have put it in your earlier paragraph): the power source, ie, the solar cell battery assembly which will add VERY significantly to the system cost. Even for those who already have some solar panels, they're unlikely to be anywhere near the home self sufficiency level required to make the cells plus inverter + Tesla PowerWall a viable proposition.

Posted by:

14 May 2015

Your line, "...working on the PowerPack, a more cubic battery that will store..." I think is incomplete. What's a "more cubic battery?" Were you going for "more bigger?" Still not very well grammar. :)

EDITOR'S NOTE: I meant cubic as in the primary definition of the word: "having the form of a cube." Perhaps "more cube-shaped" would be better? (See http://www.merriam-webster.com/dictionary/cubic)

Posted by:

Mac 'n' Cheese
14 May 2015

Yeah, and electric lights in homes were once considered playthings of the rich.

[Non-politically-correct old joke: Thomas Edison, on a exploratory trip out west, was asked if he would be willing to install electric lights in the outhouse of an Indian village. When he agreed, Edison became the first white man to wire a head for a reservation. (You have to be old enough to remember Western Union's ad, "When traveling, always wire ahead for reservations" to get the joke.)]

More to the point: I'm all for the Powerwall. Go, Elon! Cost is relative. As the cost of nonrenewable energy inexorably goes up, the relative cost of solar power generation coupled with battery backup goes down.

If not for visionaries like Elon Musk (and Thomas Edison), we would all end up praying for someone to invent SOMETHING to bring us out of darkness.

In fact, if it weren't for Thomas Edison, we'd all be watching television IN THE DARK!!!


Posted by:

Jim Guld
14 May 2015

I see this technology to be useful to RVers, especially the ones who boondock off the grid for extended periods. I want to see that application in the near future.

Posted by:

Ken Tucker
14 May 2015

This doesn't instantly make 'going off grid' a money saving endeavor, but it's a big step forward toward practical and affordable battery systems. With the cost/efficiency of solar generation improving steadily, cheaper batteries bring the future just a little a bit closer. I'm not buying a PowerWall today, but ...

Posted by:

J. B. Van Wely
14 May 2015

It will be interesting to see how Solar City markets this to its base of installed solar.

Posted by:

Art Sulenski
14 May 2015

You make no mention to life of this battery. Having to replace one ever week would not be cost effective. Compare it to a lead acid battery which is what most solar power systems use.

Posted by:

Daniel Wiener
14 May 2015

Last year we had a solar power system installed in which the company (in this case Verengo, although other companies such as Solar City offer similar plans) owns the panels and covers all the costs and maintenance for 20 years, while we just pay for the electricity (at cheaper rates than from the Edison utility company in California). So far it has worked out very well, and has saved us an average of about $100 per month. Edison acts as the leveler, supplying us with electricity at night and on cloudy days, while buying any excess electricity produced by our solar panels on bright days. (That's also good for Edison, although they're loathe to admit it, since their peak energy demand is in the daytime and especially in the hot summer when everyone's air conditioning is on.)

The only problem is that we're still intimately tied to the utility grid. If there's a power blackout, or a disruptive earthquake, we can't use the electricity from our solar panels. It would have been nice if we could detach from the grid under emergency circumstances to directly utilize our solar panels, but to do that we'd need a local storage system. Otherwise our electricity consumption might sporadically exceed the output of our panels (e.g., a cloud passing overhead, and at twilight fading into night). That's where the Powerwall battery packs could be really valuable, albeit there would need to be additional control circuitry to harmonize the switch-over. I'm hopeful that the companies offering solar installations will also offer this as an option in the future.

Posted by:

14 May 2015

It is probably worth a mention that Tesla's factory in Nevada will dry up springs as far away as about 100 miles, and lower ground water by as much as 150 more - or 450 feet more in some areas -- leaving ranchers and farmers without an income and will change the entire ecosystem not for the better.

Getting rid of farmers and ranchers and most desert life that depend upon surface water will NOT bring back the ancient desert that once thrived there just as it will not bring back water stolen from the people themselves. Reno has been out of water for the last 50+ years, all the water used by Reno is brought up from VASTLY DEEP wells leaving home owners to their own, and imports water several hundred miles from the North.

Some places cannot support HUGE populations, Reno and Vegas are but two -- more and more towns are ghosting out because of the lack of water. Were it not for the EPA and environmental reviews, most of the towns north and East of Reno would already have locked up their doors to go where the water is. The desert cannot support heavy water usage for very long - and Reno is right at that tipping point today. Sorry to be a buzz kill, but cities of millions of people living off the reserves of water a million years old won't last much longer. When you use more than you have, everyone gets into trouble.

Posted by:

Donna Crane
14 May 2015

I had solar installed, with help of tax credit 4 yrs ago, and have saved about 60% over the previous electric bills. I am on the Grid though and with any Grid outage (a rarity in Phx) I am as up-the-creek as everyone else. Would love this Powerwall, and could probably afford it at $3500, but not with the added $5-$7K cost of installation. Hopefully, all these costs will drop significantly like solar panels did. Love the innovation coming from Elon Musk & Tesla.

Posted by:

15 May 2015

mac 'n cheese -- to be more accurate you should probably substitute the name of Nicola Tesla for Thomas Edison in your comments. Nice that Elon Musk is finally given credit to the name of Tesla.

Posted by:

David Morrison
15 May 2015

To help readers understand this more fully, I have been living off grid for about 10 years now. I had to replace my lead acid battery bank in 2009. The retail cost was $2928. The batteries were 8 Rolls Surrette S-530 batteries; 400 amp hours each; 24 volt system, 2 strings (so total 800 amp hours). So if my calculations are correct they would provide (if drained!) about 19 KWh. These batteries are rated for 7 years. The Powerwall is rated for 10 years.

I keep wondering if the Powerwall will work for my next battery bank. Hate to have to get 2 though, but it still might work for me. And since you try not to drain a lead acid battery by more than 20% (about 3800 KWh for my bank) one 10 KWH or even the 7 KWH Powerwall might work.

Posted by:

J Bergmann
15 May 2015

A step at a time, gentlemen... A step at a time.

Shortly before Mr. Edison made the above-referenced trip, the entire Sioux Nation might have said: "What is electricity, and what does it do?"

It is easy to see why Mr. Musk is so wealthy. Good Luck, Elon!

Posted by:

Gary Volz
15 May 2015

I too would like to know what the battery life is of the batteries in the Powerwall?

Can the individual batteries be replaced or do you have to buy a new Powerwall unit when a battery fails?

What is the cost of an u=individual Battery and how doe that cost compare with other battery types?

When the recharge (solar or grid) power goes off how long would batteries maintain there charge if you were able to untilize them - what KW for what period?

Posted by:

15 May 2015

I understood from the article that the cost for one battery is $3.500.

But how long is that battery going to last?

If it last forever, it is very cheap, but if it lasts only 3 years, and then you have to buy new, then it increase the monthly bill for $120 (which when you add the costs of instalation of collectors and other equipment become expensive), thus it is totally useless - it is cheaper, at least in Macedonia, to pay to the electricity company.

Posted by:

16 May 2015

One could argue that many Americans are looking at the problem from the wrong angle. Instead of striving at great cost to be 'technology frontiersmen' and set up their own 'energy islands', they ought to cut and rationalise their energy use.

LED lighting, new high-efficiency appliances, fans instead of air-conditioning, quality insulation are easier and have a much better ROI (and smaller ecological footprint) than banks of solar panels and batteries.

Some Americans live on isolated ranches and the like but the vast majority dwell in towns and cities where the grid makes sense. Instead of 'going it alone', they should be pressing for publicly-owned, politically accountable utilities that use 'green energy' where possible and load-balancing systems and incentives to rationally scale grid infrastructure to demand.

This also means getting to grips with the American housing industry and its predeliction for jerry-built homes that use energy like there is no tomorrow (and at this rate, there will be no future). America's love affair with suburbia does not help matters. The Germans meanwhile are building purpose-built homes that need virtually no heating and cooling and at a price just 10% higher than 'normal' construction.

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