back to article Tesla Powerwall: Not much cheaper and also a bit wimpier than existing batteries

It's pretty and batteries are ugly – but Tesla's Powerwall is more like an incremental change than a radical disruption. Given that the hype over Elon Musk's Tesla Powerwall announcement has reached all the way from The Verge calling the colours “lickable” (no, not likeable) and tossing in a hypegasm over Musk's “best keynote …

Dear El Reg - read the specs again - it's 2kW continuous with a "Peak Power: 3.3 kW" read the presskit http://www.teslamotors.com/presskit/teslaenergy

Further it's all very well talking about existing technology potentially being cheaper - but the whole point of getting away from lead acid batteries is because a) you need a dedicated room to put them in and b) they give off hydrogen when charging - leading to a potentially explosive situation.

As for your off-the-grid comments - did you watch the presentation? It's pretty clear he means developing countries could use it to live off the grid - the sorts of places that don't know what an AC unit is or a dishwasher.

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Yup, I live in one of those countries, we have no solar, but shore power is normally 8 - 12 hours per day, the battery bank keeps us going during outage, if we need to power washing machines/iron we wait for shore power or start the generator.

The Tesla units would have been an option for us, but we have just replaced the battery bank 16*225Ah, 5 years time though it will be on the list, people in the Europe and other parts of the world, where, if the power goes out it makes the news, need to remember this is not the norm for everyone.

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Anonymous Coward

Efficiency is the fifth form of power

These batteries have cute bezels and presumably a nice Tesla-flavored marketing campaign, but they won't and can't change the world.

In order to take advantage of new forms of power, we must re-evaluate our uses of the old forms. Working from a much lower energy budget, it would be insane to come up with ideas like air-conditioners, hair driers, clothes driers, etc. Working from primarily DC, our home would look more like an RV - small fridge, LED lighting, a couple of laptops.

In addition, there must be a feedback loop- the user and his devices must intelligently communicate with the power source and work from a single energy/economic budget in order to cooperate intelligently in fulfilling the user's goals. For example - knowing the batteries are low, the power system would decline to power the microwave, but would continue to supply the laptop. The PowerWall looks like an attempt at 'greenwashing' a standard home, but magically requires no changes from the user's lifestyle.

This power wall is like all other Tesla projects - some attractive bezels, marketing hype, and fairly standard tech underneath, all with fairly poor systems thinking, such as - how does this product fit into reality?

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I can see power companies offering this to properties that are too expensive to lay power cable to.

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Anonymous Coward

johnnymotel suggested: "I can see power companies offering this to properties that are too expensive to lay power cable to."

You realize that this gadget still needs power going into it, right?

It's a rechargeable battery.

You realize that 10kWh is closer to zero than it is to practical.

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I'll probably have to 'get me coat' but..

How the fuck do you snaffle that one off the wall and stick it in your car?

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The details and math matter.

The problem here is that most people don't know how much power they use, or what the alternative product really costs. Also, look at our target markets.

Lead-acid batteries are terrible - just think of how often you have to replace them in cars. Have you figured more frequent battery replacements in your numbers? Also think about the extra controllers and inverters and stuff. Does the way the powerwall is presented, it looks like it comes with its own electronics and inverters? Better figure that in with your math. Lithium batteries, even at a much higher cost per amp hour are a much better bargain in terms of lifecycle costs. An integrated unit with built-in electronics will be even better.

Someone who wants a single one of these for net-metering and the occasional 2-hour power-out is not expecting this to be a complete solution. He isn't going to run around his house and turn everything on the moment the power goes out. He is going to notice how his neighbors are out and be happy that he has just lights and air conditioning. He will be ok with turning off the TV and waiting till the power comes back on to start baking cookies and running the iron.

Someone who is using this to cut the cord will not look like the average homeowner. They will already have more energy-efficient appliances, and have fewer of them. They will likely have insulated their home really well and put solar panels on the roof and a ground-source heat pump. Their electricity requirements will be much less than the average. These people are willing to spend the premium to go off grid, and in the grand scheme of the super efficient home and solar generation 20 or even 30 grand is not as big and scary as it sounds, especially if it is simply rolled into the house loan. For them it is not a question of batteries or generators - it is a question of which battery and how much of it.

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Re: The details and math matter.

"The problem here is that most people don't know how much power they use, or what the alternative product really costs. Also, look at *our* target markets."

http://forums.theregister.co.uk/user/74820/

Anyway, as per the previous, how the fuck do I get if off the wall and put it in my car?

Oh.. silly me. I'm not 'rich enough to ask'.

I'll get me coat.... again.

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I have been in the solar field for 14 years and lived off-grid

very comfortably for the last four years. With a properly designed system

there are few compromises to make. Learn your loads and your limits.

Batteries have been the weak part of the system and L-ion batteries are

head and shoulders better than FLA (flooded lead acid) much easier to

maintain, much deeper depth of discharge before damaging the batteries,

and most importantly, up to 3-5,000 cycle-lives (10+ years).

Use common sense with them. Don't short circuit the terminals, charge and

discharge residential L-ion batteries at a capacity/2 (C over 2 hours) rate or less. Cars

and planes have a cooling system that permits faster rates. Slow rates

are easy with solar charging.

Inverters make AC power from DC and determine the rate at which you can power devices.

Batteries determine the overall capacity of your system in kWh. FLA batteries can be discharged to 50% depth of discharge and remain viable for 3-5 years. Lifetime depends on caring for them, keeping plates covered with electrolyte, using distilled water to refill them, and don't allow ANY batteries to

remain at a low state of charge for long periods of time.

Use LPG, propane, or natural gas for heat applications, furnace, water heater, clothes drier, or cooking as much as possible. Fossil fuels are still more cost effective than electricity for heat. Solar is good for water heating and space heating but needs backup for cloudy days. Living off-grid requires a generator backup for cloudy periods.

Buy the most efficient appliances you can find, like LED lights. Seal windows and doors as tightly as possible. Have as much insulation as is practical. We use 13-17 kWh per day, even with a big-screen TV, two full sets of office equipment, and a booster pump for well water.

The Powerwall will make living without grid power much more practical, and early adopters will begin to erode the nearly 100% market share of traditional central power plants. US utilities complain about >5% penetration of solar as a "non-dispatchable" (intermittent) energy supply while Germany and Denmark already have 30% penetration.

There is plenty to learn.

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"Use LPG, propane, or natural gas for heat applications, furnace, water heater, clothes drier, or cooking as much as possible. Fossil fuels are still more cost effective than electricity for heat. "

That will change - and quickly - if CO2 control regulations kick in as hard as I suspect they will in the next decade.

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Pint

@HES "We use 13-17 kWh per day"

If I was using only $1.50 or $2.00 a day in electric power, then I wouldn't bother going off the grid.

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Where do look up what TCO is?

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Anonymous Coward

Where do look up what TCO is?

Google, but it's Total Cost of Ownership.

In this case, the business case is more for Tesla than most of the people that are looking at this thing.

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Anonymous Coward

Hmm

Is a Powerwall enough to charge a Tesla?

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Anonymous Coward

Re: Hmm

"Is a (10 kWh) Powerwall enough to charge a (85 kWh) Tesla?"

Yes, to +11.7% charge.

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Re: Hmm

The powerwall has 10 kWh. The Model S 70D has....you guessed it .... 70 kWh. So you would need 7 of them to completely charge the Model S off of the Powerwall.

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Regulatory Hurdles may be a problem

Where I live in the US you don't just plonk some solar panels on the roof, hook them up and go, you have to negotiate with the power utility a small systems generation package. Since solar is so common its a proforma, just a whole lot of words, but hidden in the fine print is things like 'no batteries'. The electricity you generate isn't free, either -- you have to pay standing charges and the like which are typically the utility dumping a share of the infrastructure cost on you. As a giveback we do get total energy tariffs, but what that means in real life is that we swap surplus power generated during the day (which the utility sells to my neighbors at Tier 4 rates) for power used at night (which we'd typically be paying Tier 1 rates for) -- in plain English, they're making 25-30c a Kw/hr on our surplus power. (...but that doesn't stop the utility from grumbling about them....they'd like to see these tariffs disappear....)

So you think "I'll just disconnect from the grid entirely". Enter H&S or its clone -- its actually illegal to do this in some parts of the US.

As far as power use goes, if you're at the solar panels stage then you've probably gone through the house systematically reducing power consumption. You should be using tiny amounts of power compared to a decade ago (and remember that if you have A/C that immediately bounces back on the power draw for cooling -- less power means less heat which means less energy needed to remove it). This is where our naff 110volt plugs help, BTW -- compared to a ring main they're a joke, a maximum of 2Kw a circuit, but now everything's so low power it doesn't matter any more. (So if you're using older appliances, lights and so on -- spend the money on upgrading them, not on a battery....)

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Anonymous Coward

Re: Regulatory Hurdles may be a problem

"So you think 'I'll just disconnect from the grid entirely'."

Most of those people don't even see the irony of becoming "self sufficient" and "independent" of modern society, with their imported Chinese solar panels and high tech Japanese battery packs.

One hail storm and they'll be down at the local Red Cross begging for a generator.

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Anonymous Coward

Numbers...

The $3,500 one is 10 kWh.

At (for example) $0.10 per kWh, that's a dollar. YMMV, feel free to adjust.

If the power that goes is in completely free (e.g. solar surplus), and if the conceptual in-and-out cycle is once per day-and-night, then congratulations, you'll save $1/day or $365 per year.

Personally, I wouldn't even walk across the street for $1 per day. I'm certainly not going to pay $3,500 plus plus plus for the privilege.

Batteries are to energy storage what a yak is to transportation.

The good news is that they "only" need to get twice as good about one or two more times and they'll be simply wonderful.

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Anonymous Coward

Oh...

Given the name of the company, I'd have hoped they'd found a way of harnessing Zero Point energy, rather than a bunch of AA batteries in a nice box.

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Pint

Re: Oh...

"...a bunch of AA batteries in a nice box."

I hope that they're at least 18650 form factor. If not larger.

AA would be daft.

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Re: Oh...

The irony given the name of the company is that Nikola Tesla was the inventor of polyphase AC and his archrival, Thomas Alva Edison, saw a future with direct current.

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Alert

the ten-year warranty OR

Ten year life, MINIMUM?

A warranty says more about marketing policy than it does about product life.

What sort of batteries are still good after 10 years of daily cycling?

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Angel

Normalise the peaks?

Couldn't all the powerall's in the local neighbourhood be shared via a local microgrid to help normalise out any sudden peaky demand from a house?

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UK regulations?

Having read through, it looks as though you can't (without a lot of expensive safety kit to prevent you frying a power worker who is trying to fix a fault) use this as a whole house UPS. There are similar constraints on powering your normal house wiring from a backup generator. You have to be safely disconnected from the grid before you power it up.

So it seems to be a potential method of buffering the grid by storing off peak electricity and then feeding back into the grid during peak load. Presumably the circuitry would be much like that for solar panels, which disconnect during a power failure. Which can be frustrating if the power is out and the sun is shining.

There has been talk of using the batteries in electric cars to do much the same, although not much has come of it so far. So this could be an option if you don't have or want an electric car, especially if you live in an appartment in a high rise block without a dedicated (electric powered) parking slot. In this case solar power isn't an option either, of course.

So in the UK this is looking (as with solar power in the home) like yet another opportunity for the affluent investor who owns property and can afford to tie up capital over ten years or more to be subsidised by the less fortunate to meet Government green targets.

What is needed in the UK is massive buffering capacity for renewables such as offshore wind farms which currently seem to waste a lot of power (where the grid can even accept their power) and also screw up the economics of running conventional gas generation to cover for when the wind isn't blowing.

Any advance in storage technology is good.

However at the momemt the major benefit seems to be for the developing world where the is no grid or an unreliable one.

This may all change, of course, if supply in the UK exceeds demand due to loss of generating capacity, and we have to restructure our domestic power to cope with rolling brown outs. Again the affluent are likely to cope better than students in bed sits and tenants (especially those on housing benefit) who will suck up the pain and subsidise the rest.

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$350 to store 15 cents' worth of power.

These cells make excellent sense for a vehicle. But if there's no weight penalty, it's a struggle to find a use case that doesn't involve showing off.

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