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Tesla's Household Battery: Costs, Prices, and Tradeoffs

Technologist Ramez Naam (hat tip to Tyler Cowen's "Marginal Revolution" blog) has taken a look at the economics of Tesla's new wall-mounted household battery system, and concludes that it's "almost there," at least for many places in the world -- and seems to already make sense in some. From his analysis: For some parts of the US with time-of-use plans, this battery is right on the edge of being profitable. From a solar storage perspective, for most of the US, where Net Metering exists, this battery isn’t quite cheap enough. But it’s in the right ballpark. And that means a lot. Net Metering plans in the US are filling up. California’s may be full by the end of 2016 or 2017, modulo additional legal changes. That would severely impact the economics of solar. But the Tesla battery hedges against that. In the absence of Net Metering, in an expensive electricity state with lots of sun, the battery would allow solar owners to save power for the evening or night-time hours in a cost effective way. And with another factor of 2 price reduction, it would be a slam dunk economically for solar storage anywhere Net Metering was full, where rates were pushed down excessively, or where such laws didn’t exist. That is also a policy tool in debates with utilities. If they see Net Metering reductions as a tool to slow rooftop solar, they’ll be forced to confront the fact that solar owners with cheap batteries are less dependent on Net Metering. ... And the cost of batteries is plunging fast. Tesla will get that 2x price reduction within 3-5 years, if not faster.

25 of 317 comments (clear)

  1. Not Actually $3500 by sonicmerlin · · Score: 5, Insightful

    I don't know how this guy wrote the entire article without realizing it, but as Tesla explained in a Bloomberg article the cost of the 10 kWh battery's full installation plus inverters is $7100, not $3500, if you buy outright, and $5000 if you lease. It's just way too expensive. Battery tech needs to come down to under $100/kWh to become more mainstream, and solar panels need to drop to about half or even less of what they are now.

    1. Re:Not Actually $3500 by Khyber · · Score: 4, Insightful

      Plus inverters? No. Plus inverter. That pack, if you look at the specs and do some math, is good for a single ~20A 120V circuit, given that it's sustained discharge is ~2kWh and peak is 3kWh. Reality is more like 15A. I wouldn't trust that pack for more than one room of my home. One for each room and multiple for the kitchen given the power drain an electric stove does per burner, be it element, induction, or IR, microwaves, dishwasher, refrigerator...

      --
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    2. Re:Not Actually $3500 by nm03101 · · Score: 5, Informative

      This guy copy-pasted his entire review from Gizmodo.

      He's a plaigerist, not a technologist.

      he's listed as the author on Gizmodo...

    3. Re:Not Actually $3500 by Rei · · Score: 4, Interesting

      Burning natural gas, aka heat, is not a "higher grade" energy than electricity, it's a lower grade energy. Electricity can be converted losslessly into heat. Turning heat into electricity loses a large chunk of it.

      I agree though that 2kW sustained / 3kW peak is too low for most people - even if they don't use an electric stove. Yes, one can arrange to not use multiple high consumption devices at the same time, but the goal needs to be to not make people's lives more complicated. It's so easy to forget what you have going, too... I always forget that I can't run my microwave and my electric kettle at the same time because they're both on the same circuit and combined it's too much power consumption.

      --
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    4. Re:Not Actually $3500 by ArcadeMan · · Score: 4, Funny

      It's a 7404, right?

  2. Why? by Anonymous Coward · · Score: 4, Funny

    Coal is far more cost effective.

    1. Re:Why? by R3d+M3rcury · · Score: 4, Funny

      Yeah, but it's pretty messy. I mean, have you ever shoveled coal? I wouldn't want that in my house.

  3. Time by rtb61 · · Score: 4, Insightful

    Time will alter everything. Reality is, the more batteries produced the cheaper they will become and much more interestingly, the more batteries installed, the fewer people paying for electrical mains infrastructure, the much more expensive per user it becomes. That economic boulder rolling down a hill, faster and faster and faster, inevitable. Tesla still needs to do a complete system, ready to install by franchised installers (ensure quality installs), keep it simple. Not to forget, the Tesla power pack would be a strictly utility device, much like adding air conditioning, or a verandah, it adds capital value to the property. So forget the incumbent PR=B$ about measuring it against electricity charges because that is only part of it's value, it has real capital asset value and that value also needs to be added in, to more effectively compare it what is in affect rent and burn (rent your part of the infrastructure and burn your capital inputs).

    --
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    1. Re:Time by drinkypoo · · Score: 4, Interesting

      I think electric vehicles will start showing up at the unexpected places.

      I think the place they will dominate first (and next, I guess) is motorcycles. The only thing missing from most current electric motorcycles is top speed. Most people don't ride long distances on them, so it's an ideal kind of vehicle to hit next.

      --
      "You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
    2. Re:Time by thesupraman · · Score: 4, Insightful

      Honda CTX700 already gets 64 MPG in a reasonably large/comfortable commuter bike.
      The Honda GROM 125, which is more compact, is being reported by users at over 100MPG

      There is significantly less room for electrics here, since bikes can already quite easily be very efficient, and
      the added weight as a percentage of total mass is much higher than a car.

      Sure, there is a niche, but thats already pretty well catered for with steppies, and those are often already
      around 100MPG at 'city speeds'

      Touring/Cruiser/etc bikes dont want electric on the whole (except again in a marketing niche). Harley etal already
      intentionally put piss poor engines in their bikes for pure marketing reasons, with horrendous fuel economy, terrible
      performance, and horrible weight - because thats what the market demands.

      Electric bikes will exist in cities for noise/political reasons, and as a fashion niche, but will not become commonplace
      for some time.

  4. Another market overlooked by Anonymous Coward · · Score: 4, Interesting

    All the discussion I've seen about this Tesla announcement has focused on [1] time-shifting electricity demand and [2] storing electricity from on-site generation. Those are the major uses, no argument. But another one is serving as a whole-house UPS. In some parts of the US (like the NE, where I live), a LOT of people have gasoline or natural gas/propane generators that automatically kick on when the power goes out. Many of these system, which are often as expensive or more so than Tesla's battery system, get pressed into service only a couple of times per year, and then for a couple of hours. A battery system can't replace a generator for long outages, of course, but for short-term issues, this is a non-trivial extra benefit.

  5. Re:Price won't come down by ShanghaiBill · · Score: 5, Interesting

    Model S battery pack uses 25kg of lithium.

    Lithium costs $6/kg. So that 25kg costs $150, or about 0.2% of the cost of a Tesla Model S.

    the price of lithium will skyrocket

    There are 230 billion tonnes of lithium in the ocean. It can be extracted from seawater for about $20 per kg, with current technology. That is about 3 times the current price, but would still represent only a fraction of 1% of the cost of an electric car, and a modest portion of a home battery system. New technology could push the price of seawater extraction below the current world price. Lithium will not be a bottleneck.

  6. Last Sentence... the point of this exercise. by BenJeremy · · Score: 4, Insightful

    Musk knows that to reduce the cost of EVs, the cost of making batteries has to go down, and the easiest way to do that, AND the best way to build up infrastructure, is to ramp up production.

    That's what this is all about - not about making money, at least in the short term. Tesla just needs to have sales drive (and justify) the increase in production, and when the price of making those batteries drop, EV sales will become more attractive to a larger customer base, thus ramping up production more... rinse, lather, repeat.

  7. Re:Price won't come down by BLKMGK · · Score: 4, Interesting

    Do we get fresh water with that lithium extraction? If so that makes this even more attractive!

    --
    Build it, Drive it, Improve it! Hybridz.org
  8. Backup Generator replacement? Not so much by endoboy · · Score: 4, Interesting

    TFA makes much of the Tesla battery as a replacement for backup generators.... at 7kWh, it's equivalent to about 4 hours from a low end generator.

    Not anything that's going to replace my Honda and it's 20 gallons of gas any time soon.

  9. Re: Wow thats a great summary by Anonymous Coward · · Score: 5, Informative

    Net metering is when you have an energy producer (solar, wind, fuel cell, etc) that can at times produce more power than your house demand. The meter could flow backwards, meaning you are credited for the energy you produce. Some states don't have that, where the meter only spins one way, forward, so any back fed energy is blocked or has to be dumped to a battery or resistive load.

    Time of use means you are charged different rates for electricity at different times of the day, as a function of wholesale price fluctuations. This is good and bad, since you lose price security but you can get the most benefit out of conservation.

    Mixing the two lets you use a battery to arbitrage the price of energy, where you charge a battery at low prices and discharge at high price times. This works best with wind generation that tends to overproduce at night.

  10. Lead Acid by Bob9113 · · Score: 4, Interesting

    Lead acid batteries are still about half the price per kWh (look near the bottom, at the 48v x 400Ah bank), and come with the same 10 year warranty. Cars care about weight, houses don't.

    The new thing here isn't battery storage of solar power, it's lithium-ion batteries instead of lead acid. The price performance for lithium-ion can't compete with lead acid yet, when weight isn't a factor.

    1. Re:Lead Acid by aXis100 · · Score: 5, Interesting

      Im not convinced. It's good that you've rated that pack at 50% depth of discharge (48V x 400Ah = 19kWh nominal, approx 10kWh @ 50% DoD), but typically lead acid packs will only get 1000 cycles at that rate. You typically have to go to a 30% DoD to get 10 years / 3000 cycles.

      Lithium can do greater depth of discharge for far more cycles. The overall lifetime costs of lithium per kWh were already starting to beat lead acid, and the new Tesla pack is even better.

  11. Re:Backup Generator replacement? Not so much by Waffle+Iron · · Score: 5, Insightful

    OTOH, in a real crisis, that might be the last 20 gallons of gas you get your hands on for a good while. The solar powered system refuels itself.

  12. Batteries with Solar Systems = No Net-metering by catchblue22 · · Score: 5, Interesting

    Companies like SolarCity basically install solar systems for no money up front, and then lease them back to you for a period. For many houses, even with these fees, the SolarCity systems will save the homeowner quite a bit of money. Licenses to sell power back to the grid are usually restricted, even in states they are allowed. If you have a battery system installed, you will no longer have to sell your excess solar energy back to the grid. You'll simply be able to store it in your battery for later use. Thus, homeowners with these systems may not have to apply for licenses for their solar systems, since they will not be doing net-metering. This will allow many users to install solar panels who couldn't before. It removes the ability for utilities and/or state governments to restrict the number of homes with solar panels. This is why these batteries will likely have a huge impact.

    --
    This and no other is the root from which a tyrant springs; when first he appears as a protector - Plato (423 to 327 BC)
    1. Re:Batteries with Solar Systems = No Net-metering by jblues · · Score: 4, Interesting

      Companies like SolarCity basically install solar systems for no money up front, and then lease them back to you for a period. For many houses, even with these fees, the SolarCity systems will save the homeowner quite a bit of money. Licenses to sell power back to the grid are usually restricted, even in states they are allowed. If you have a battery system installed, you will no longer have to sell your excess solar energy back to the grid. You'll simply be able to store it in your battery for later use. Thus, homeowners with these systems may not have to apply for licenses for their solar systems, since they will not be doing net-metering. This will allow many users to install solar panels who couldn't before. It removes the ability for utilities and/or state governments to restrict the number of homes with solar panels. This is why these batteries will likely have a huge impact.

      Here in the Philippines, its allowed for any homeowner or business to sell electricity back through the grid. It took me a lot of research to find this out - its not widely publicized at all, and I haven't seen many folks taking the option. It could be a great option given pretty good (2200 hours) of sun per year and very high priced electricity, which as it happens is often used for cooling during the day. I guess that given a per capita GDP of something like $7000/year most people can't afford this yet. . . On the other hand much of the commercially produced electricity is from renewable sources, particularly hydro and thermal, but some of the small villages have their own solar plant - provides only enough for basic needs.

      As it happens we have not a smart meter in front of the house, but one of the old magnetic kinds that will (AFAIK) happily run in reverse.

      --
      If it acquires resources on instantiation like a duck, then its a shared_ptr<Duck>
  13. Re:Price won't come down by ShanghaiBill · · Score: 5, Interesting

    Do we get fresh water with that lithium extraction?

    Desalination plants work with reverse osmosis, which converts seawater to freshwater, with concentrated brine as a by-product. That brine is a better starting point for lithium extraction than seawater, so, yes, they could be co-produced.

    But extracting either from seawater does not really make any sense. Some mid-east countries desalinate so they can pursue idiotic schemes to grow wheat in the desert, when they could just buy wheat for far less. California has a few desalination plants, because of dumb policies that vastly inflate the cost of water to urban consumers, while subsiding the delivery of rainwater to farmers growing rice and cotton in the desert.

    Likewise, lithium from seawater is not economical, and is unlikely to be so in the foreseeable future. It is better to extract it from salt deposits, or existing brine pools. But the seawater extraction cost is a clear ceiling on the price of lithium, and negates any prediction of a lithium supply crisis.

  14. Simply not true. by microbox · · Score: 5, Informative

    As of 2015, the total levelized cost of coal is in the ballpark of solar/wind. (Levelized cost includes capital costs, but does not include pollution costs -- consider how cheap coal is that we count the cost of medical bills, let alone AGW.) In a few decades, it will be cheaper to use renewables than mine coal to run an existing coal plant. Notice how fast Kodak went out of business? That is what the coal industry is staring down.

    --

    Like all pain, suffering is a signal that something isn't right
  15. Re:First Household Post by ganjadude · · Score: 4, Funny

    I woulda had first post, but its dark out and I dont have a tesla battery yet to store my solar power :(

    --
    have you seen my sig? there are many others like it but none that are the same
  16. Re:Price won't come down by Neil+Boekend · · Score: 4, Insightful

    For home batteries the mass doesn't matter that much. Price/kWh is where the ball is at.
    Assuming what you say is correct it still is irrelevant for this discussion.

    Mass of a lithium atom is approx 7 by the way. You forgot the neutrons for lithium, and they weigh in approximately similarly to the protons. You did count the neutrons for aluminium which is dodgy to say the least.

    AFAIK what matters in the end is the weight divided by the number of electrons you can store in an atom. Aluminium can be oxidized to 3+ easily. This comes out to 9 atomic weight per electron.
    Lithium can go to +1. This comes out to 7 atomic weight per electron. Still better than aluminium but the gap isn't as big as you claim.

    --
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