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Tesla launches line of Li-ion stationary storage systems for homes and businesses: POWERWALL and POWERPACK

Multiple POWERWALL units may be combined. Click to enlarge.

As widely expected, Tesla CEO Elon Musk unveiled the company’s new product line: scalable stationary battery systems for homes, businesses and beyond. Available for immediate order on the Tesla Web site ( or is the modular wall-mounted POWERWALL system, which is targeted at homes and perhaps some small commercial applications, Musk said. Delivery is projected for sometime later this summer (3-4 months from now.)

The sleek, sculpture-like Li-ion packs come in 7 kWh ($3,000) and 10 kWh ($3,500) configurations. Both are guaranteed for 10 years (with an optional 10-year extension), and can be combined to up to 9 units—i.e., up to 90 kWh of storage. The packs contain all the integrated safety systems, the liquid thermal control and the DC/DC converter, and work with solar systems straight out of the box, Musk said.

Tesla POWERWALL unit. Click to enlarge.

Round-trip DC efficiency is 92%, power output is 2 kW continuous, 3.3 kW peak. Voltage is 250-450 volts, with 5 amp nominal current, 8.5 amp peak output. The POWERWALL units are rated for indoor or outdoor installation, and operate in the range of -4°F to 110°F / -20°C to 43°C. The POWERWALL requires installation by a trained electrician; the AC-DC inverter is not included.

The 220 lb (100 kg) unit measures 52.1" x 33.9" x 7.1" (130 cm x 86 cm x 18 cm), and comes, noted Musk, in different colors.

The fact that it is wall-mounted is vital. You don’t need a battery room filled with nasty batteries. A normal household can mount these in the garage or outside the house.

—Elon Musk

The POWERWALL units will initially be assembled at the Fremont plant, Musk said, and the ramp will be slow. a plans to transition production to the GigaFactory in Nevada next year, resulting in a higher ramp.

For larger scale systems, Tesla is proposing the industrial POWERPACK, which, Musk said, is “designed to scale infinitely. This could be a GWh solution.” Musk said that a Tesla is already working with a utility that wants to do a 250 MWh pilot. (The entire evening livestream event was powered by POWERPACKs.)

At the conclusion of the streamed announcement, Musk said that solar panels and batteries represented “the only path I know” that could transition the world to sustainable energy. He suggested that 2 billion POWERPACKs could fully transition the world to a solar/battery future, and observed that it is “within the power of humanity to do so.



'power output is 2 kW continuous, 3.3 kW peak.'

So if your freezer is running, don't try to boil a kettle.

Prices do not include installation and the inverter.


Solar + storage is OK near the equator, but when you get further north, you get very short days in winter and more or less no usable sun for 2+ months of the year.

+ Even in sunny places you get monsoons etc when you get days of no sun.

I can see that you could get to an 80% solution (solar+storage) at a high but manageable price, but going to 100% would be extortionate.

Thus, you will need the grid or a generator.

The problem then is how do you pay for a grid that people are taking 75% less electricity from.

You will have to keep all the capacity for winter days and expect to pay for it during the summer when you don;t need the grid.

Else, as @DM pointed out, you might use the grid for spikes (Kettle, electric power shower) all year round and main power during the winter.

Setting the rules and costs for this will be a bundle of fun.


The 10kwh unit is only rated for once weekly cycling!
So it is good for 520 cycles, which if it were counted on a per kwh basis comes out to $1kwh if the inverter and installation are included.

For the daily cycling 7kwh unit, assuming it is rated at usable capacity, then 10 years is 3,650 cycles.

At 7kwh and with the capacity assumed to decrease to 80% over the period the average is 90%.

So 3,650*7*0.9 = 22,995 kwh

At $3,000 for the unit that is 13 cents/kwh just for the box to cycle the load, not counting the cost of the inverter, installation, or interest on the capital sum expended.


Anyone know what they are talking about with the 92% round trip efficiency since no inverter is included?

So now there's a Tesla you can afford to put in your garage.

As I mentioned in posts a few weeks ago, this is one of the few appliances you can buy that will actually earn a positive rate of return after depreciation. This appliance throws off cash if you live in a region where there is a decent spread between peak/off peak, or where you can't get net metering for solar.

Very exciting that this technology is going mainstream.



Lets see your math then.

Randy Bryan

Who provides the 250v-450v inverter?


Apparently not all of them work, so if you already have an inverter for your solar array you may be out of luck.


There was an article here a few months ago about a company offering grid scale storage for about $160/kwh with life cycles up to 10,000. Sounds much better than what Tesla is offering, but what is truly amazing is that the Tesla announcement is covered on the websites of all of the major news outlets I look at. For a simple battery pack?


Davemart, that is what I say too.

My story concerns my older fridge that the local utility wanted me to replace. In their promotions, flyers with the bill and a feature in the local newspaper etc, I happened to notice that the model depicted was the exact same model that I had. Installed in May '96 and working perfectly ever since I should add. I was therefore motivated to phone the utility and see what their figures were for an 18cu-ft fridge consuming 683Kwh/yr - which I admit is not stellar performance in this class.

Well, this otherwise know-it-all authority could not supply any financial proof of savings or ROI and said I should check with the metal recycler who's 1-800 number was in the promo as it is they who actually run the program. Spokesperson for the recycler said his responsibility was merely to get my address and pick up the fridge - which, incidently, must be in good working order??? Huh, the nerve.

As for Mr Kettle back there. I use a 800W microwave to heat water for instant coffee, and a gas range for an actual kettle when I make tea. But that's just my english heritage. Regarding HVAC, I'm retired so it's safe to leave some windows open with bug screens in place most days. I will allow that there are days when humidity dictates employing the HVAC to dehumidify the house before things become unbearable. In California I think this may not be an option.

A suggestion that Lead Acid batteries working out at $100/Kwh would be a cheaper solution met with disfavor by a friend who had served as a volunteer fireman. Apparently this type of backup solution has been known to have caused call-outs after someone was puttering about in the basement, while smoking and in the vicinity of cells which happened to be gassing at the time.

TESLA's competence in thermal management of lithium ion energy storage enables safe in-home installations that will hopefully promote changes in the HVAC industry. Why not DC current compressor feeds ? Then there's the problem of 110vac LEDs, why not change to 24Vdc lighting circuits at the breaker/fuse box? Going forwards for the power receptacles, what really needs to be operating on 110Vac that now requires upwards of 50 receptacles in the average house ?


2kw average power draw is ludicrously inadequate, and the 3 and a half hours it will last for just as bad.

My guess would be that when the average American fridge freezer comes on, it will use most of the power.

A decent kettle will use as much as the peak power.

If you want to do without electricity in an emergency, spend a couple of hundred on some camping equipment.

If you want to live with anything remotely resembling normality, buy a generator.


'Powerwall comes in 10 kWh weekly cycle and 7 kWh daily cycle models. Both are guaranteed for ten years and are sufficient to power most homes during peak evening hours. Multiple batteries can be installed together for homes with greater energy needs.'

Which is a flaming lie, unless most US homes don't have anything drawing more than 2kwh more than briefly.

BTW, since the weights are given as the same for both the 7kwh and 10kwh versions, they have clearly used the same cells in both, and have simply given 3kwh more slack to enable daily cycling.


Apparently air con units need over 3kw to run, and over 12kw to start them up.

That is one of the reasons why back up generators are 20-25kw, not the 10kw or so that are needed on average for a home.

This ludicrous bling is rated at 2kw.

Most American homes don't use air con then, according to the increasingly bizarre Musk those who connive at his stock pumping.

Anthony F

I agree that 2kW continuous and 3.3kW peak is rather low. I think these first-generation units will supplement grid power, not replace them. Its the Tesla Roadster of home battery packs (you buy one to have another car, not to replace your daily driver).

If your house is pulling 4kW, then you'll get 2kW from the grid and 2kW from the battery. If you want more then buy more and daisy chain them, but I doubt it'll be economical at anything less than grid-scale applications with industrial inverters that get 95%+ efficiencies.


Apparently air con units need over 3kw to run, and over 12kw to start them up.

Then I would respectfully say that if your air con pulls a 12Kw surge at start up, then it's time to replace it with more modern equipment which doesn't rely on motor control technology from the 1950's.


you bring up some great points. Would you please compare this Tesla pack to those home H2 units we're all waiting to buy for our HFCV? LOL


No worries.
Here is one of the early installations in Europe:

Only 700watts, but this is designed to cover hot water too, and so the combined heat and power must be considered.

Burning NG with way more efficiency than the grid can do as that throws away the heat means that it is far more of a total solution which also combines well with solar panels, although obviously it is less mature than batteries.


Hi T2:
I simply used the figures someone else did without adverse comment or correction on another blog.
Since I do not live in the US I have found it difficult on other occasions to work out what typical US spec equipment is.

Two questions:
Are the differences you suggest enough to make a very material change to the requirements suggested?
That back up generators have often been uprated in the latest models from 20kw to 25kw suggests not, in relation to a source which can only provide 2kw continuous.

What specs would you suggest are appropriate to a reasonably modern although perhaps not state of the art air con installation?

Here in the UK heating systems are very different, and air con in the home very rare, although I happen to have it in an air source heat pump, which though runs on different principles.


10 kWh ($3,500)
..good price



Oh come on! You're doing it again. You're picking apart every little detail and say that this would never be sufficient to supply a home with 2kW with 3.3kW peak...yada yada yada. Then turn around and tell us about a .7kW H2 generator? LOL

You think that half the homes in the US don't use gas to heat their water and/or their home heating? LOL

You question the 92% efficiency and then ignore that you lose efficiency in converting the NG to H2 and then lose another 50% efficiency on the fuel cell itself?

If you're going to keep claiming your open to "multiple alternate technologies" then you've got to stop being so blatantly hard on batteries/EVs while picking them apart at ever opportunity and then not only giving a pass to fuel cells...but making excuses for their every shortcoming.

You bring up very valid points...but do it fairly on BOTH sides.



They are very different ball games, as a battery will do nothing at all for much of household energy consumption, which is NG.

So overall fuel savings are much greater from using even a very modest fuel cell, which is not intended to provide stand alone back up, only contribute to electricity production.

The electricity production is a freebie from producing the hot water.

Fuel cells are undoubtedly at an earlier stage of development than batteries, so this is a trial, as opposed to the full scale deployment that Tesla proposes for its batteries.

I have not got anything at all against battery back up, but it should do what it says on the tin, and this doesn't.

A home version of this however would:

The lithium titanate technology is tough as boots, and a 10kwh unit would produce an ample 20kw.

Cost is the thing, but if you are using a less capable chemistry the unit that Tesla is offering is impractically underpowered.

30kwh and 10kw continuous would offer something, whereas this offers very little.

Account Deleted

Here is a link to Musk's presentation of the Tesla power systems. One commentator called it the best tech keynote presentation by any CEO ever in history even better than Steve Jobs presentations of the iPhones. I agree. It is really good. Musk have you convinced that Tesla has a product you can order now that you can afford and that can make a real difference for a better future for all of us. Now homeowners in the Northern hemisphere will have an option to become pollution free during summer and spring using Tesla Powerwalls, solar cells, a geothermal heat pump and battery electric cars.

I noted that musk during the presentation said Tesla was in talk with a utility to deliver a 250MW backup system based on the Powerpack! So it is truly scalable. Also good to see that Tesla can deliver 10kwh for only 3500 USD at the pack level. That is the lowest price 350 USD per kWh I have ever seen for such a battery backup system. The powerwall weights 100 kg so 100wh/kg which is not much. For that reason and also because the cycle life of the Model S batteries is not high enough to support a 10 year warranty on a battery that will see daily deep cycles for ten years I am convinced Tesla uses another battery cell for those Powerwalls and Powerpacks than they for the Model S. May still be a 18650 cell though.

Account Deleted

Also nice that up to nine Powerwalls can be connected giving the owner of a large house a 90kWh storage with 18kW of continuous power and 30kW of peak power. That should cover the needs of 98% of all house owners (including Davemart who need 4 Powerwalls) and for those 2% with more need than 9 Powerwalls Tesla's Powerpacks will be applicable. There are already several million homeowners globally with solar roof power and many more millions are coming on line in the future so Tesla's power systems will have a very large market especially since Tesla's systems are the most affordable and practical that currently is on the market.


I think people have this the wrong way round.
This is not designed to take you off grid, it is to enable you to spread your Solar energy across the whole day and reduce, but not eliminate, the amount of power you take from the grid.

Thus, if you have a 5kw solar and one or two of these, you will need very little power during summer, spring and autumn,excepting peaks (power shower, kettle+freezer etc.)

During winter, you could use it to shift low rate night power to day time use, while taking 90% of your power from the grid.

Thus, they are NOT a solution for going off grid, they ARE a solution for reducing the amount of power you take from the grid.


Someone commented that apparently the SGIP money goes to the customer in California, not the provider.

If that is the case, and the perks are not grabbed in fancy lease terms in Solar City installations, then clearly nearly free is good.

I don't like wall mounted for 100kg units, nor do I think it is a great idea to have several too small modules, so I would prefer a 14kwh unit capable of daily cycling, with output a more practical 4kw continuous, floor standing as the base model.

If the tax system means that other tax payers are effectively paying for your system, then even this is good though.

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