Tesla's price shock: Solar + battery as cheap as grid power | RenewEconomy

Tesla’s price shock: Solar + battery as cheap as grid power

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New pricing for Tesla Powerwall suggests solar and battery storage now competitive with grid power. For about $16,000, consumers can slash their grid bill to almost nothing and not worry about blackouts. The strategic and commercial implications are marvellous or frightening, depending on your vested interest.

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tesla_powerwall_2-640x360Last week, Tesla launched their Powerwall 2.0 residential battery storage system, a little less than a year after Powerwall 1.0.

Compared to Powerwall 1.0, peak power has increased by 40 per cent, continuous power by 50 per cent, storage capacity by 100 per cent (to 14 kWh) and an inverter is included. And all this for US$5,500 ($A8,800) – about the same price as Powerwall 1.0.

In other words, the price per kWh stored and re-used has halved in less than a year. Indicative installed prices in Australia are a little over $10,000. The commonly accepted wisdom was that battery costs would decline more gradually than the precipitate decline seen in solar PV costs. This has been proved wrong.

Let’s do a solar PV+battery+grid versus grid-only price comparison.

First, let’s assume a 4,800kWh per year household in Adelaide and that its electricity bill is either the average of all 77 market offers after all conditional discounts, or the average of all 77 Market Offers before all conditional discounts, from the 16 retailers operating in Adelaide (data from MarkIntell).

For solar PV, let’s take the median installed price of a 5kW system (data from Solar Choice) and let’s assume a 20 year life with zero residual and 20% purchase premium for on-going maintenance. For battery, let’s take the indicative installed price ($A10,300) and assume a 10 year life with zero residual.

Let’s also assume an operating regime that sets the daily household consumption against solar PV production and battery storage as far as possible. This results in 8,373 kWh per year solar production, 200kWh of grid purchases and 3,773kWh per year of solar PV export to the grid.

Putting this together and annuitising the capital items at 2 per cent real (the typical mortgage rate), we get the result shown in the chart below: PV+battery+grid is level-pegging with the average grid-only Market Offer (after conditional discounts) and cheaper than the average grid-only Market Offer (before conditional discounts).

bruce mountain solar plus storage

This is astounding.

A typical household in the suburbs of Adelaide can now meet its electrical needs with solar and battery storage for about the same amount they would pay on a competitive offer from the grid.

And no need to worry about black outs or bill shock: for an outlay of around $16k and assuming a suitable roof, consumers will be able to reduce their grid bill to almost nothing (revenue from surplus PV exports paying for the grid fixed charge plus the little energy bought from the grid to cover rainy days). And the set-up more than pays its way.

Of course one can argue with any of the assumptions I have made, but they seem plausible to me and the calculation itself is not tricky.

Electricity in Australia is deeply interesting at the moment. Of all the fascinating issues competing for attention, this tops my list.

It has obviously profound implications for consumers, PV and battery producers and installers, electricity retailers, centrally dispatched generators, network service providers, market operators, regulators and governments.

The strategic and commercial implications are marvellous or frightening, depending on your vested interest. It’s worthwhile studying this carefully.

Bruce Mountain is the Director of CME and co-founder of MarkIntell.

Update: The chart below has been updated to include GST on electricity purchases, which the first chart did not.

As the author writes: “The initial chart had included General Sales Tax on battery and PV but not on electricity purchases. The revised chart accounts for the fact that the majority of households will not be able to deduct GST on their electricity purchases. By properly account for taxes in this way, the gap between PV+battery+grid versus grid-only is larger than initially calculated.”

bruce mountain solar battery grid comparison

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  1. suthnsun 4 years ago

    And if you manage to use some of your production charging your car you are even further ahead

    • Peter Campbell 4 years ago

      More and more will include car charging in the mix. Say another 5 to 10kWh/day. Many will not have the opportunity to charge during the day because the car will be away from home.

      • nakedChimp 4 years ago

        Then the place ‘away from home’ better offers that, no?
        Looking around Cairns I don’t see a lot of solar on business roofs, nor parking lots shaded by solar pv..

  2. Brunel 4 years ago

    Powerwall 2 was unveiled 548 days after Powerwall 1.

    A lot of grid lovers have tomato/egg on their face now.

    • Carl Raymond S 4 years ago

      The grid has a future role – as a battery leveller. It’s like the pipe connecting multiple water tanks – one big reservoir instead of many small.

      • juxx0r 4 years ago

        Which could mostly be done with 10A extension cords available from Bunnings.

        • nakedChimp 4 years ago

          I had 3 of them in the outdoors during dry season for 2 months.. you don’t want to do that for long 😉

        • neroden 4 years ago

          I think it’ll be a little heavier duty than that. But it’ll be like the ordinary residential distribution lines, not the big transmission lines which everyone complains about.

    • Adam Smith 4 years ago

      Don’t you worry about the grid, it will survive, but will have a different focus. Many customers will also not be able to afford to install their own systems, so the Retailers will offer packages. Large users, such as industrials, ports infrastructure etc, will also still require grid connection being unable to generate enough power on site, plus those with excess and large scale generators will still need the grid to export.

      • ben 4 years ago

        The grid is excellent for peer to peer trading, arbitrage and virtual grids / generation. The smart network requires a grid for us to sell electrons

      • Peter Campbell 4 years ago

        As soon as people get electric cars, they will see merit in staying on the grid.

  3. Carl Raymond S 4 years ago

    History texts will contain this phrase:
    “The Great Energy Disruption began in the late 2010s, with the opening of Tesla’s Gigafactory 1 near Sparks, Nevada, USA. Within the space of 5 years, oil and coal stock prices collapsed, triggering…”

    • Chris Fraser 4 years ago

      … and that most of the Australian government were too thick to see it ….

      • phred01 4 years ago

        Wait till this hits the polies Josh & Barnaby will be running around like like headless chooks

        • Ian Gordon 3 years ago

          Will be !

      • nakedChimp 4 years ago

        Not ‘too thick’, just acting in the interests of their ‘masters’.

      • Barri Mundee 4 years ago

        Not too thick I think, more in the pocket of the vested interests who want to delay and frustrate the transformation even they can foresee for as long as possible.

        • John Mitchell 3 years ago

          Here here!

          • Edward Green 3 years ago

            *Hear hear. Tricky language, English.

      • Daniil Vodopian 4 years ago

        Who cares about the government, if the residents install the solar and stop paying for the coal ?

        • Chris Fraser 4 years ago

          True, I’m not convinced these idiots are trying with their energy policy. They’re just idiots.

    • Geremida 4 years ago

      Love it Karl, whoops Carl

    • Phil 4 years ago

      Yes and Solar City / Tesla are looking at 10GW of output per year .

      They just announced a shut down of a 1.6GW coal power station in Australia , and 700 jobs .

      Well 10GW is 6 of those a year gone and about 7000 NEW installation jobs created.

      • neroden 4 years ago

        Australia won’t get *all* the Tesla output! You’ll be lucky to get half of it. There are other places bidding for that output!

        • Phil 4 years ago

          I was thinking Globally , and how Tesla seem to be the biggest driver of change and volume

          Australia is about 2% of the worlds GDP , so based on that and our sky high energy prices we might consume 5-10% of the output.

          A bit like Toyota Landcruisers. Australia used to consume 10% of the Japan factory output. Until the UAE countries started to buy even more than we did.

        • JonathanMaddox 4 years ago

          We only have 20 coal-fired power stations left, but we won’t be able to shut them all down in
          40 months. Give us a decade or so.

          • Mark Roest 3 years ago

            40 months from now is Oct. 2020. They may not be shut down by then, but the price of renewable energy on demand (via battery storage of intermittent energy, and demand response) will be so low by then that they will all get scheduled for closure. When is your next federal election? and the one after that? Figure that if there is a major election in 2020 or 2021, the Coalition should be out on its ear, and the winner could publish the coal plants shut-down schedule within 6 months after that — to cheers from around the world.

    • Kenshō 4 years ago

      Doesn’t secure Tesla’s ongoing place in history, when everyone else merely drops their $kWh price to match and keeps their battery the same size.

      • Carl Raymond S 4 years ago

        Counting on it. The world needs a hundred gigafactories. Tesla can’t build them all.

        • Kenshō 4 years ago

          The argument Tesla is making the price of cars and batteries as cheap as possible, as soon as possible, no longer stands.

          • Carl Raymond S 4 years ago

            I don’t understand. You’re not suggesting the gigafactory could ramp faster?

          • Kenshō 4 years ago

            PW 2 was made bigger instead of cheaper.

          • Remiel Pollard 4 years ago

            He made it bigger for the same price, which means it’s cheaper.

          • Kenshō 4 years ago

            The materials have an ecological footprint and the earth isn’t bigger. It’s dearer.

          • Martin Sevior 4 years ago

            Kenso, your arguments are all over the place. Tesla is clearly ahead of the game. If people want smaller, less costly batteries other manufacturers can fill that niche.

          • Kenshō 4 years ago

            The article topic is Tesla’s positioning of their new home battery product and who their new flagship product is catering to. There’s been no mention the PW 1 model will be continued at a lower kWh price and it appears the 100% larger PW 2 will be their only product in that sector of the market. It is a cultural issue. The US goes to election this week primarily around issues of socio-economic status (SES). No, my comments are targeted around accessibility of renewable energy. Exactly what game is Tesla ahead of???

            “The U.S. — with $63.5 trillion in total private wealth — holds the largest amount of any country in the world. But that wealth is unevenly distributed, and nowhere is that more evident than in the U.S., which also has the largest wealth inequality gap of 55 countries studied, according to the report.”
            http://fortune.com/2015/09/30/america-wealth-inequality/ https://uploads.disquscdn.com/images/b36ae01baece8f9d4e042e74b35a64639b763747c79e532bd0f2acf4d904e11f.jpg

          • Martin Sevior 4 years ago

            The game Tesla is ahead of is leading the charge towards a truly sustainable renewable energy economy. For that purpose it needs to develop a business model that delivers a profit independent of government subsidies. Bundling the inverter and power electronics with improved battery storage provides a really nice boost in price/performance for the total system cost. From my perspective, the cost of a total solar + storage system has fallen from around 46cents/KWhr (PW 1 + PV + inverter + associated power electronics) to around 20 cents/KWHr – ahead of the cost of the grid where I live.

          • Kenshō 4 years ago

            Yes and only an off grid home or an energy inefficient home need 14kWh of overnight storage with a 7kW peak/5kW continuous inverter for $10k.
            For energy efficient homes maintaining a grid connection, 7kWh of overnight storage with 3.5kW peak/2.5kW continuous inverter for $5k would have been adequate. It’s important to remember a large hybrid inverter will not result in bill reduction, as it is rare to turn allot of high power appliances on at once. I know first hand, a 2.5kW inverter makes my property almost invisible to the grid and the property has performed well in three extended grid outages.

          • neroden 4 years ago

            You’ve done the math wrong, Kensho. I have an energy efficient home with a grid connection and I definitely need a Powerwall 2 sized battery.

            Why? Electric car. Adds a significant amount to the power draw. Obviously Tesla’s thinking about this!

            If you’re in an urban location where you don’t need a car, your electricity needs will be lower, but in that case *you also probably live in a duplex, condo, or apartment building*, and the building as a whole will want a Powerwall 2 sized battery.

          • Kenshō 4 years ago

            It’s a vicious circle for those who presently don’t need nor can afford a 14kWh battery or an autonomous driving EV. Most Americans are focused on paying electricity for cooking and heating.

          • JonathanMaddox 4 years ago

            It’s not a vicious circle. Such individuals are not really in the market for a smaller battery either, and can wait another year for prices to halve again (including the inverter price) and/or enjoy the benefits of people with higher demand withdrawing their load from the grid and contributing the arbitrage of their battery storage towards grid stability and efficiency.

          • neroden 4 years ago

            No, we’re actually way behind that stage, Kensho (what country are you in?!?). Most Americans still heat with natgas, and about half still cook with natgas (including me).

            That has to be converted to electricity eventually to deal with global warming; even though modern heat pumps are very efficient, it’s still going to be a massive increase in electricity usage.

            I have a super efficient home. But converting *everything* to electricity (automobile, heating, yard tools, etc.) does mean that the electric usage ends up rather high.

          • Kenshō 4 years ago

            I’m in Australia. Before I added solar/storage I have a 5.5kWh/day average usage on my electricity bill. That’s with three adults, electric induction cooktop, lithium tools. The average house uses 18kWh/day, so I concede many people use more.
            Clearly our perspectives are different because “usage in the end state” is less of a consideration for me. I’m interested in the faster solar uptake now. I’m concerned a 14kWh battery is a large first stepping stone for entry to get moving and a large step size for future expansion.
            The main difference between us, is I imagine your anticipating an energy utopia. Looking at the world as a whole, we’re a long way away, especially with Tesla designing products for the richest 1% of people in the world.

          • neroden 4 years ago

            Yeah, I do tend to be a long-term thinker.

            I also figured out a while back that Tesla’s “working down the demand curve”. They can sell batteries at exorbitant prices right now, because there are some markets which will pay those prices — so they do so and make outsized profit margins. Once these early adopters buy the batteries, I fully expect them to slash the prices, probably in half again.

            When the price hits $2500, I think a 14 kWh battery will be a pretty decent step size. One will cover efficient homes. Mine… well… once I switch my heating to electric, being in the snowbelt, I’m expecting to be using 64 kwh/day just for the heating in midwinter (practically nothing in summer however). And obviously most of that heating will be at night.

          • Kenshō 4 years ago

            Very interesting. Ok that makes sense. There’s no point arguing with humanity’s consumption and it makes sense to begin with those who consume allot and can presently pay to consume.

          • Kenshō 4 years ago

            Top 1% in the World:

            “an income of $32,400 a year will allow you to make the cut. Using current exchange rates, that amounts to roughly:

            29,185 euros
            2.2 million Indian rupees, or
            211,126 Chinese yuan

            So if you’re an accountant, a registered nurse or even an elementary school teacher, congratulations. The average wage for any of these careers falls well within the top 1% worldwide.


          • Kenshō 4 years ago

            with tending “to be a long term thinker” it is a pattern in the mind which keeps it driven to ward off negative feelings. It is a subtle form of anxiety which disrupts a deeper peace. There’s always a “story” there is a purpose to the activity though what’s happening is the activity is motivated by negative feelings, hence the desire to get to a better feeling state, yet the better feeling is never achieved while the mind is driven. The way out is to accept the feelings in the present and see how they arise.

      • neroden 4 years ago

        The general view is that in the short term (1-3 years), nobody else has the ability to drop their $/kwh price to match, with perhaps one or two exceptions. There’s room for three battery companies.

        • Kenshō 4 years ago

          This article reckons PW2 is A$10k installed. That means any manufacturer making a product for less than $10k is in the market, especially manufacturers making entry level products, able to be expanded in step sizes. Economies need momentum. Biodiversity is being lost forever. Water and food security challenges are here. Soon your cities won’t be getting the same food stuffs arriving on shelves.

        • JonathanMaddox 4 years ago

          With the five computers.

    • Victor 4 years ago

      … on February 29 2022, at 3:45:44 pm, a Tesla vehicle traveling on Interstate 40 west of Albuquerque, achieved self-consiousness…

      • Carl Raymond S 4 years ago


      • illiad88 4 years ago

        That was bugs bunnys backstory too.

      • Edward Green 3 years ago

        “…became self-aware…Now we’ll have to rename it Skynet…”

    • Hans the Elder 4 years ago

      Maybe American textbooks. The European textbooks will say: The Great Energy disruption began in 2000 with the German Renewable Energy Law that enabled renewable energy technologies to get their costs down by upscaling and learning-by-doing.

      • Carl Raymond S 4 years ago


  4. solarguy 4 years ago

    Hello Bruce, An installer company I contacted about the cost of the Powerwall 2 yesterday, quoted me $15,300 installed, no PV, so I don’t know how you arrived at $10k installed.
    You would need a lot of extra PV to pay for SAC charges in regard to exporting excess production.

    • Ruben 4 years ago

      I agree, it’s overly optimistic. For now at least.
      Though Tesla estimates $9,450 installed in Australia: https://www.tesla.com/en_AU/powerwall

      • solarguy 4 years ago

        Yeah, that’s right. When the first one came out it was touted as $3k, reality set in when the real price was given.

        • Brunel 4 years ago

          U$3k without an inverter.

    • juxx0r 4 years ago

      An installer company i contacted said powerwall 1 had a positive ROI, so it’s quite clear some of them know SFA.

      • solarguy 4 years ago

        Some will lie through their arse to get you in.

      • neroden 4 years ago

        Well, where *are* you? If you’re urban or suburbs, then yeah. If you’re ultra rural the Powerwall 1 did have a positive ROI.

    • Chris Fraser 4 years ago

      I’m hoping there is a bit of a ‘market demand’ premium included in that quote.

      • solarguy 4 years ago

        Don’t know Chris, but remember the first Powerwall was only $3k, but turned out to more. The thing people should think about is having an integral inverter, if it goes tits up you can’t use your solar production.

    • Michael Skeggs 4 years ago

      Suncrowd.com.au are offering them at $10400 installed as part of their current sth NSW bulk buy.

    • Phil 4 years ago

      Wow that is price gouging , should be around $9500 for a basic install

      I wonder if they are NOT an authorised Tesla Distributor and are simply putting 50% profit margin on someone else’s install?

      Or perhaps they are cherry picking and bumping up the prices on installs a little too far out of their prime install area

      Nothing illegal about that , why it pays to get 3 quotes

  5. MaxG 4 years ago

    This calculation has many assumptions. Assumptions equal risk. In this case, the risk was numbers that are too optimistic, hence, reality does not look as bright as made up. E.g. to offset meter, solar, supply charges, I need to export almost 30kW @ 3Cents to break even. A 5kWh system with some self-consumption will not manage that. Based on my average usage of 16kWh per day, and a 20kWh battery which can be depleted to a SoC of 20% (=18kWh usable), I still import 200kWh/year form the grid, due to ‘PV adverse’ weather conditions. This is based on real data, which can be found here: http://www.pvoutput.org/list.jsp?sid=34144
    However, I love the prospect of it all — we are getting there, and I like it 🙂

    • Michael Skeggs 4 years ago

      200kWh is about $56. Hardly smashing the calculation with a $16000 capex!
      And there is much more sensitivity to changes in power prices or FITs. The calc in the article was based on 14kWh a day usage.
      There is significant risk of increases in power charges, this approach removes that risk and removes almost all the exposure (except to standing charges).

    • solarguy 4 years ago

      Your right Max as my previous post here states, the numbers don’t stack up.

    • EV Positive 4 years ago

      MaxG I agree with you questioning the calculations, the assumptions are plainly wrong. The author assumes constant 13kWh (4800/365) daily consumption year round, and that the PV has enough to charge the PW2 battery on all but 15 days (200kWh / 13). As your pvOutput data shows, this is simply not the case. Also electricity demand for winter heating is exactly when PV supply is at its worst. If only winter was 15 days long!
      If you want a simple calculation, the most the PW2 can “save” you is 10kWh/day * 365 days * your power price. eg 10 * 365 * 25c = $900/year. And you can’t charge the PW2 all 365 days a year on PV output alone, so the situation only gets worse from there. Most of the benefit in this article is coming from the PV, not from the PW2 which is still not quite cost effective.
      However the future is looking bright, PW3 will certainly tip the balance.

    • John Silvester 4 years ago

      Back of the envelope calculations for a system as dynamic as PV with battery storage is problematic.

      Using 30min Demand and PV generation data, and calculating export; import; battery SOC; battery charge / discharge; battery charge losses for each 30min block for an entire calander year and also sub-divided into Time of Use (TOU) blocks to allow for fixed and TOU rate Tariff comparison.

      Using data from a household with an average daily demand of 12.44 KWh (slightly less than the 13.15 kWh used in the OP) and a 5kW PV system I find the following:

      Fixed Rate TOU rate PV only

      Electricity Bill Reduction 75% 75% 49%
      Electricity cost Reduction -10% -11% 30%
      ROI -0.95% -1.02% 7.73%
      Simple Payback 14yrs 14yrs 8yrs
      PV Self Consumption 55% 55% 22%

      From the data it is clear that PV with Battery is getting close to the cost of grid supplied electricity. It is also clear that PV only still has a large financial advantage.

  6. Adam Smith 4 years ago

    What an astounding shift in less than a year! I have sold my Redflow shares as I cannot see anybody competing with this. This is only the start, in another year it will be even better.

    • Phil 4 years ago

      Redflow shares are way down as expected
      Unless they drop the price it’s hard to see a single advantage for that technology except
      in remote sites where it can remain dormant without any charge for a long period

      The 5kw continuous , 7kw peak output from the Tesla inverter is a game changer too and it’s all under the 1 manufacturers warranty.

      Anyone concerned about Lithium batts catching fire could always mount the unit outside , i know i would. Maybe have a self destruct mech if anyone tries to steal it ! ( just joking)

      I’m 100% off grid now but i’m hoping to buy a “runout” Powerwall 3 at the right price when my Batts are due for replacement in 2021. Who knows it may be 28kwh for $6k (aus $) as a runout buy only.

    • Tomfoolery 4 years ago

      I’m about to sell mine too. They have zero chance of competing with this. Hackett’s whingepiece yesterday on this site didn’t do their brand any favours either

    • Miles Harding 4 years ago

      We shouldn’t write off red-flow too soon. Flow batteries have the capacity to greatly increase storage kwhs at low incremental cost, which would give them a competitive advantage.

      • Phil 4 years ago

        Miles they doubled the Tesla KWH output for 15kg more weight ( to 120kg from 105kg) and included the inverter. And the size is not radically larger

        The redflow Z-CELLis already pretty big , to double the tank sizes to double the capacity is possible but where would the consumer put it ? It cant be wall mounted at all and It would roughly double the weight too

        For larger installations it may be a more viable product , but i think their home use sales will taper right off now.

        • nakedChimp 4 years ago

          What I said about flow-batteries all along.. they can’t compete in private residences because of volume.

          • MaxG 4 years ago

            This one you got right :))
            Size like an IBC…

        • Miles Harding 4 years ago

          I would agree – flow batteries are better applied at a larger than daily household level, probably suitable for community and off-grid where the big tanks are leess an issue and the low self-discharge storage, a benefit.

          I wasn’t concentrating on the weight, but as you mentioned it, Nissan has done the same with the 60kwh leaf, which is rumoured to weight only 100kg more than then 24kwh version.

      • MaxG 4 years ago

        Given the price tag, they will never flow for me!

  7. Phil 4 years ago

    The Tesla Powerwall 2 , if you use 1 of them , is only suitable for NON HARDWIRED appliances as it’s single phase 5kw continuous , 7kw peak

    So to run a full sized electric cooktop , air conditioner or hot water booster element (all are hardwired) you would have to either convert to another energy for those or run 2 or more Powerwall 2’s

    Even electric Induction cooktops use typically 6kw ( or more) with 4 elements going , although so efficient not for as long or all the time.

    So it’s either gas for serious cooking for a family or Buy 2 of 2 element induction cooktops to split the power across 3 powerwalls. With perhaps the hot water booster and electric oven sharing those too as they are typically 2 to 2.4 kw each . The 3rd Powerwall can do the lights and powerpoints only , effectively a 3 phase all electric system

    But if you go to this effort and cost you might as well go off 100% off grid

    I’m guessing most will stay on the grid and use it for the Hardwired appliances and 1 or 2 teslas for all the Rest. Still saves a lot of money though with just about every Australian state paying back the 1 powerwall within the 10 year warranty period. Typically 7 years.

    The high electricity prices in Australia mean massive Grid demand reduction is inevitable. And a lot sooner than imagined. Certainly until EV’s become mainstream , and who knows what will be the preferred option then , on or off grid ?

    • Ruben 4 years ago

      How does it know what’s hardwired and what’s not? Or do you have to plug all appliances into the powerwall off 100m extension cords?

      • Phil 4 years ago

        You house switchboard will always have separate Circuit breakers for each hardwired appliance. i.e Air con , HWS booster , electric Cooktop.

        They all draw different currents so are separate circuits and circuit breakers for this and to allow isolation for fault finding and repairs. Some like cooktops and Air Conditioners also have thicker wiring

        When they install the 1 powerwall they likely will only connect to the powerpoint and lighting circuits.

        Check a typical switchboard and look at each fuse or circuit breaker . Each one of those is a separate wire just feeding that circuit.

        The back of the switchboard can be accessed to access any or all of those circuits. But ONLY by a licensed electrician of course. The owner / user should NEVER touch the switchboard except to reset a circuit breaker or replace the fuse .

        • Peter Campbell 4 years ago

          I find it strange that the battery is only rated to deliver 5kW. I have a LiFePO4 battery, now 8 years old, in my DIY converted car that has slightly fewer KWhs than the Powerwall 2 yet it can happily produce about 25kW continuously and more than double that peak. If the Powerwall cells are the same as in the Telsa cars then they are better than the Li cells I could get 8 years ago, so why can’t they do more? Are they just being rated very conservatively or it is the inverter that sets the limit, or both?

          • MaxG 4 years ago

            Different technology… what a lot of people forget… LiFePO4 rocks! I have got a 20kWh LiFePo4 battery, (and am very pleased with it).

          • Peter Campbell 4 years ago

            Yeah, but, my other EV, an iMiEV, is more Tesla-like Li chemistry, and it can perform similarly to my DIY LiFePO4 car with 16kWh producing 60kW. For that matter, a Tesla car with 60-90kWh of presumably the same cells as the Powerwall 2 can produces high hundreds of kW. Scaling that down to 14kWh, the cells should be able to manage many 10s of kW, even if they are only just as good as what is in my Mitsubishi iMiEV.

          • Phil 4 years ago

            The Inverter sets the Limits i would say

            And the cooling system is designed around that 5kw Continuous 7kw peak too. It is rated from -20 to + 50 deg celcius so that requires significant cooling and heating control

            This is pretty good though. A locally made Offgrid inverter that is 5kw continuous (12kw peak) , such as Selectronics , are approx $6k each.

            Some others from Taiwan such as MPP solar offer 18kw continuous output for the same money

            Both costs are without batteries and are offgrid systems of course.

            And NEITHER offer a 10 year warranty (assuming the Tesla Inverter is also covered as part of the 10 year warranty)

            Many will buy 2 powerwalls or more to boost the output

          • Chris Fraser 4 years ago

            50 kW peak sounds like a goodly amount (considering EV is so much more efficient than ICE). I hadn’t thought LiFePO4 could do it. Maybe your setup is many small batteries in series.

          • Peter Campbell 4 years ago

            My DIY car conversion has 45 x 90Ah cells in series. Officially rated for 3C. 8 years on and with some capacity loss so closer to 70Ah now, I can pull 500A out of them if I put my foot down, albeit with a fair bit of voltage sag. 50kW in a small, light car (1991 Daihatsu charade) gives very decent performance.

          • Ian 4 years ago

            Yes, how many cells does a battery pack pack, if a battery pack is made of identical lithium cells?

          • eveee 4 years ago

            Because LiFeP has much higher Power/Energy. Its a trade off. Chemistry with higher C has lower energy. LiFeP C rate is as high as 10. But its bulkier and has a higher cost/kwhr. They use it in portable drills and such. A123 used it to make cells with C rates of 25. You have to exercise great care not to short them. To do higher energy, you lower C.
            Tesla/Panasonic has made great progress in increasing energy ( 100kwhr packs) and reducing cost. PowerWall2 half the cost of PW 1.

          • Ian 4 years ago

            The gigafactory makes only penlight sized lithium batteries . The new ones are 2170 in size 21mm diameter by 70 mm long. They use these in motor vehicle battery packs and in stationary power walls. Nothing mysterious here. Just hundreds of little cylindrical lithium cells connected together, with cooling and some electronics. Powerwall1 had slightly smaller cells 18650’s these were 18mmdiameter x 65 mm long.

            It seems all the cells are made in exactly the same way. The different cell amperage rating is a grading issue, out of the same machine some cells turn out better than others.

            The electronics component sets the power output of the powerwall, and that must be a marketing and engineering design issue

            It’s not clear what exactly the specs are for these cells but it seems to be roughly 3.6 v x 5000mah. The older format 18650’s are 3.6 to 3.7 v x 3000mah or less

            If you take a 2170 cell and drain it rapidly it will tend to overheat and will tend not to last too long, to ensure longevity they designers limit the current out put.

        • Jeff Wehl 4 years ago

          I think you should look at some more logging. The average home pulls around 400W over night. During the day its rare to see peaks above 4kW. We have several LG Chem systems running off grid just fine and that using Gen 1! Both LG and Tesla Gen 2s will happily run an average home off grid even if it includes a small air conditioner.

          • Phil 4 years ago

            Does that include electric cooking using a traditional stove top ?

            I assume your using Gas for cooking so your load would be less

        • Carl Raymond S 4 years ago

          I don’t think many will find it undue hardship to use the microwave during a blackout; given that for the neighbours it’s candles and beans.

          • stucrmnx120fshwf 4 years ago

            Lol, I use the microwave 100% of the time, at 30% of the power consumption, retaining 70% of the nutrients, instead of 30%, if I want heat, I keep the reverse cycle air conditioning on 18°C. Besides, it doesn’t Cook the cooking containers, so I can keep them in fridge and freezer, ready to be microwave sterilized, every time they get used.

      • Andy Saunders 4 years ago

        He means they are 3-phase, not single-phase.

    • Geremida 4 years ago

      Throw away your HWS immersion heater and get a Heat pump hws – mine only uses about 1 KW. as for my induction cooktop – about 2KW for the 2 large ones on.

      • solarguy 4 years ago

        What brand of H/P do you have and many use it?

        • Ian 4 years ago

          Ours is a Sanden and 6 people use it and never runs out. it draws a max of 1100 W. It is also extremely quite and no-one hears it at all – unlike others I hear about.

        • Geremida 4 years ago

          Hydrotherm – generally 2-3 people but we’ve had 6 people and it never ran out. I set mine to come on around 8am so looking at my smart meter graphs prob 95% of the time there’s enough from the PV to run it

    • Coagmano 4 years ago

      This article is talking about using Powerwall while still connected to the Grid, so if you exceed the power output of the inverter temporarily while cooking, it will draw the excess from the grid. No need to worry about hard-wired or not

      Then when the powerwall is full and the solar panels are still producing, you sell that power back to the grid and make back some of the amount you spent on the grid.

      The assumptions in the article include a bit of buying from the grid and a bit of selling back and it still works out pretty good.

      • Phil 4 years ago

        That’s assuming the consumer does NOT want power/ battery backup if the grid fails

        Try telling a consumer they cant run the electric range hob when the grid power goes out ! Those 4 elements can easily draw 6kw on their own

        That’s why it has to be wired either for on grid to supplement power but power every circuit. Or Off Grid with only circuits connected to the Powerwall 2 that are within it’s inbuilt inverters peak load capability.

        If you have 2 or more Powerwall 2’s or even 1 with gas cooking and hot water it’s probably not an issue as the output is greater and/or the electrical peak and continuous load is much less.

        • Kenshō 4 years ago

          My inverter is rated at 2500W/3000VA.
          The manual describes the inverter can produce 13A and my model has a 50A transfer ability from the grid, so they say it must have a max breaker of 63A.
          There’s another 2500W/3000VA model with a 16A transfer ability, so they say it must have a max breaker of 29A.
          I’ve had 3 grid outages since my electrician connected the solar system to the grid and 2500W happily powers a fridge, computers, router, lights and one high power appliance (kettle, hotplate, toaster or microwave). In a power outage we accept we never run the air conditioner or the washing machine. Everyone has an agreement to only run one kitchen appliance in an outage and that has worked. The inverter red temperature LED has never come on. Worst case scenario is the inverter would heat up, warn people with a temperature LED or alarm, then if people persisted, it would turn itself off.

        • Coagmano 4 years ago

          If there was a blackout I’d be fine to be restricted to 1 hotplate and lights on. That’s still a heck of a lot more than your neighbours would have!

          Surely I’m not that unusual

  8. Breza Lily 4 years ago

    $16.000 Are very hard to find. It’s still for the rich.

    • Rod 4 years ago

      Funny, 16K is easy to find when peeps are looking for a car!

      • David Jones 4 years ago

        Problem is most people need a car to stay employed. They don’t really have a choice on that purchase. Obvious market ATM is new builds, early adopters and rural types. Thinking that the battery needs to drop to around $5K installed before attractive to the mainstream.

        • Rod 4 years ago

          As a lifelong commuting cyclist, I’m afraid you will never get agreement from me on the “need” to own a car for work. We all have choices as to where we live, where we work or how we get there. I admit kids or lack of public transport make a car attractive.

          Now I’m retired, I use my electrically assisted bike for most trips. I can’t stop banging on about how useful and how much fun these are for all ages and fitness levels.

          The gist of this article is that at this present time and at this price level, it is competitive with grid energy.
          With record low interest rates anyone could install now and expect a good pay back period. Most banks would gladly loan for this type of investment.

          When discussion around batteries become as popular as property investment around dinner tables, batteries will become mainstream.

        • stucrmnx120fshwf 4 years ago

          I’m poor myself, but if you could get a mortgage, that covers your electricity and cars, low interest rates, plus the cars needing 1/10 th of the maintenance and fueling costs, it’s hard to resist not just for the wealthy, but for the middle class.

    • Miles Harding 4 years ago

      This is where a finance package comes in.

  9. Megs 4 years ago

    And, if you are on an aged pension and affected by asset and income tests… the installed equipment is part of your home so it is exempt from asset test. If you are subject to income test then an extra dollar income from an investment loses 50 cents pension, whereas a dollar saved is a whole dollar. Similar if on a high income… Invest capital other than in a superannuation retirement pension and you earn a dollar to pay 40 cents tax and have 60 cents left for your electricity bill . Save a dollar on your electricity bill and you save the whole dollar. This is why popular retirement town Mandurah in WA has high % rooftop solar. When they can only get 2% interest on savings and then lose half of that from pension just watch them go for powerwall !

    • MaxG 4 years ago

      Not ready to retire, but our whole focus was on self-reliance, and spending the dollars now, so that we don’t when we may not have ’em… PV + battery, bore, wormfarm > so no perpetuating cost on electricity, water, and sewer… rego for a car and a trailer, Internet, and land tax… done. Food we grow too… what a wonderful life.

      • Phil 4 years ago

        The world is becoming a more erratic and uncertain place as far as essential services.

        But when you D.I.Y as much as you can most , if not all , the uncertainty about cost and reliability of those services seems to go away

        The fact that an individual can achieve what Governments ONCE employed to do that task can no longer do is firm evidence of a system in crisis that can only get worse.

        • MaxG 4 years ago

          You are absolutely right… and my reply could be lengthy, becoming off-topic… however, in short: neo-liberalism (mantra: privatise profits, publicise cost); as such public utilities should have never been sold (unfortunately started by Labour with the Hilmer Report under Keating; blatantly executed by the LNP); removal of any people power / benefit / etc. anti-unionism, labour rights, education becoming a personal cost, health, and the list goes on. Reagan in the US, and Thatcher in the UK, all did the same thing. Result: anti-social governments, in bed with corporations; see fracking and the like; and the loss of the fourth pillar of democracy: a free press.
          As I said, I could go on, but it is only the very tip of the iceberg. And then, a populace who is not educated to understand what is happening… I did not even mention the environment (actually the planet), the private pillaging, the tax evaders, the money ponzi scheme, etc.
          I am no domsdayer, but what I see tells me it will turn to sh!t, and I am glad that I may be out (dead) in a few years.

          • illiad88 4 years ago

            Well I hope you’re not Max. The world can’t afford to lose people with functional brains. There are too few of you as it is.

      • Aaron R 3 years ago

        Public schools and hospitals need to strive for self-reliance. Why should taxes be spent on supporting these perpetuating costs? A change will help direct money to be spent on actual health and education, rather than being budgeted and ring-fenced for facilities and maintenance costs. Bonus of kids in schools seeing positive changes first hand for their own experience.

    • Craig Allen 4 years ago

      When my Mum worked this out five years ago she went straight to Origin and ordered a system. To put it simply, money in the bank reduces your pension. Put it on your roof instead and it no longer counts against you, but instead pays your electricity bill. I don’t understand why the solar installers aren’t advertising this fact.

      • Megs 4 years ago

        Probably wise not to advertise and crow about it too much. Over my life as an adviser I’ve seen “a good thing” re tax or pensions get squashed when it becomes too popular. Just pass it on. Then everyone can pretend . Different story if it is “up in lights.”

        Its a good general principle for retirement though isnt it ?

        Money saved beats money earned.

        Less worry too. Like Max, below, have a home that is low maintenance, with disability access, good simple passive solar design or features, low energy and water use, close to daily services so you can totter to everything without a car, lots of neighbours and community stuff around you, use the Mens Shed and the Community Garden,, turn the family pool into an aquaponics pond 🙂

        The other big possibility comes when you combine all the technologies to enable completely elegant living “off the grid” . It will make more sense to have villages in tight clusters rather than endless sprawl and , importantly, it becomes easier to be selective about land use and conservation because you don’t have to keep joining onto the end of the utilities mains. You can leapfrog wetlands and conservation areas etc. There are many other flow on planning ideas that come from being able to make each dwelling an “earth ship’. Enjoy

        • Martin Sevior 4 years ago

          Actually I think that with electric self driving cars powered by PV the urban sprawl will continue. It’s not that much of a pain to be stuck in traffic if you can be working on a problem, reading or sleeping as your car drives to where you need to go. You need a nice big roof to get all the power you need for your house and car so big houses on the fringe will become even more desirable.

          • neroden 4 years ago

            The self-driving car doesn’t do anything about congestion. Even if the commute is pleasant, people don’t like to commute for more than an hour. People will still head towards the city to cut their commute times. This is the self-limiting factor on urban sprawl.

            The real question is where the *industrial and commercial* operations will move, the ones which people are commuting *to*. Commercial operations are heading back to cities; industrial operations seem to be going way into the hinterland, which will create some strange dynamics and probably create new cities around them, eventually.

          • Mike Shackleton 4 years ago

            Self driving cars will do plenty for congestion.

            1. Being computer controlled they can travel closer together and faster on the road than people operated cars can. There’s also been discussions about cars linking up on freeways and operating as a single vehicle.

            2. You probably won’t own your car anymore – rather, you’ll pay for a subscription and call a car from a rolling fleet up for a journey. This takes a lot of parked/inactive vehicles off the road.

            3. As per point 2, if you do a regular commute, it’s likely the booking system will plan your journey to take other passengers. This will take a lot of single occupant cars off the road.

            4. Using live (and projected, since the system will know where vehicles are going) travel data, the car will take the fastest route. A less refined version of this already happens if you use an application like Google Maps and allow it to automatically update your route based on traffic data.

          • neroden 4 years ago

            1. No, they can’t. Humans tailgate, following dangerously close. Computers will be programmed to follow at SAFE distances. They will be spaced FURTHER out. These ideas of platooning cars are extremely dangerous and will have to be banned.

            2. No, that won’t happen. People like to have their *own* car, for reasons of interior maintenance, basically. Those who don’t are already using taxis or carshare in urban areas. In rural areas, carshare is not practical because it takes the car too long to get to your house.

            3. No, it won’t. People typically take cars because they don’t like shared vehicles; if they did like them they’d be carpooling or taking the train already.

            4. Even the best systems are very stupid about “avoiding traffic”, and all that does is distribute congestion until all the roads are congested anyway. So it won’t just be congestion on the expressway, the back roads will be congested too. Not helpful.

            In short, bullshit, bullshit, bullshit, and bullshit, I’ve studied this for a long time; don’t fall for the bullshit.

        • illiad88 4 years ago

          I like the cut of your jib old mate.

    • phred01 4 years ago

      this not only true for just pensioners anyone else who pay a fairly sizable amount in tax this is a good investment. Every dollar saved doesn’t attract a marginal tax and there is a` GST saving too! If this really takes`off then govn’ts are going to find a significant drop in revenue. Sure to combat this scenario a new sunshine tax will be born ( variant of the poll tax)

      • nakedChimp 4 years ago

        They just need to roll ALL taxes into land tax and be done with it.
        A land owner is always ‘bound’ to the property and can’t run away.
        Way easier to tax that than all the other stuff that needs checking, filing, observing, intruding, etc..
        Just tax land to cover all costs and call it a day and drop the GST and whatever else you got (probably reduces taxation cost itself and set’s some people free to do something else with their life).

        • phred01 4 years ago

          problem is the libs won’t bring it in because their main constituents are landholder. The idea is to tax every one else….gst

        • MaxG 4 years ago

          What happened to you? 🙂
          This is not a solution… I can lease a place, and make millions as a business, thus pay no taxes. Na, back to the drawing board. 😉

          • nakedChimp 4 years ago

            In that hypothetical case you make millions as a business and pay no taxes.. and that differs from the current system how?

            What do you think would happen if you would roll all taxes into land holding taxes?
            All the IT companies have HQs and datacenters.. all the oil companies need refineries on ground, etc..
            They can’t run away from that stuff as they need it to operate.
            Just tax it and drop all other tax shenanigans.
            Will make it way simpler and fairer.

            Naturally the land tax would need to (as it already does in the area I’m at) be adjustable by some bidding process, so that rare/desirable land can become more expensive and other land that is not sought after could fall in tax price to get some sort of self regulation going on.

            If your product then needs a lot of land to create it will become expensive and if your product needs no land to create it will become cheaper.
            If your product relies on raw materials a lot that come out of the ground (that have been taxed) it will be expensive, but if it is low in raw resources it becomes cheap..
            Saving resources is built into it right away.
            And if someone owns large tracts of land he has to pay for that privilege and people who life in a flat in a big house with lots other people will have it cheaper (for less comfort).
            Reducing your ‘footprint’ then really does pay.

        • neroden 4 years ago

          Income tax and estate tax (inheritance tax) are important. The really ultra-rich have figured out how to put their money in things other than land. Income tax and estate tax are basically the only way to tax the bazillionaires.

          Just exclude the first $100K of income, so it only affects the bazillionaires.

      • illiad88 4 years ago

        Shhh don’t give the idiots any ideas.

    • jeffhre 4 years ago

      Yes. “Save a dollar on your electricity bill and you save the whole dollar” though that is not quite right, as you will also save the taxes that would have been required per AUD spent on electricity!

    • Phil 4 years ago

      My Brisbane Neighbour got a $17 power bill last quarter
      With the solar contribution and pensioner Discounts in Australia that’s all it is.

      Pre retirement and solar it was around $240 a quarter

      So unless they drop pensioner subsidies i cant see too many going for the powerwall just yet unless they want the power backup feature.

      • stucrmnx120fshwf 4 years ago

        Don’t forget the subsidies are reducing, especially with regard to daytime electricity, because of solar oversupply, batteries allow for power, to be stored and sold, at peak demand prices. In this way, without having to pay for electricity at peak prices and being able to sell at peak prices, that pensioner could make a profit, in this second phase, of the clean energy and transport revolution. Here comes the roaring twenties again.

    • neroden 4 years ago

      Thta’s Australia-specific pension rules (whacky!)

  10. Carl 4 years ago

    Even the Tesla website says you need two to run things other than lights, outlets and fridge https://www.tesla.com/en_AU/powerwall

  11. Richard Koser 4 years ago

    My late-night calculation was based on Powerwall cost $10k, panels $800/kW.
    Powerwall + 10kW: $18,000, runs a house
    2 Powerwalls + 15kW: $32,000, runs a house and a Tesla 3, 100km/day
    3 Powerwalls + 20kW: $46,000, runs a house and two Teslas.

    If only the cars were a bit cheaper.
    I reckon they will be once the Gigafactory cranks up.

    • Miles Harding 4 years ago

      Of course, with two Teslas, one can always be plugged in as the battery. 🙂

      What we need is a bi-directional charger on the model 3 and it would be simply a matter of plugging it in, eliminating the powerwalls. (call it powerwheels??)

      And.. it would be a cheaper battery (per kwh) than most on the market now.

      • BeyondZeroEmissions 4 years ago

        This has to be the way to go … is there any inkling of news of a formal Australian trial from anybody anywhere? ACT, perhaps? Reposit? Beast Soutions? Power Ledger? Love the Powerwheels idea!

    • phred01 4 years ago

      This `will cause a fall in revenue for govn’ts lower GST receipts & Fuel excise There are storm clouds gathering on the horizon while Nero fiddles

      • stucrmnx120fshwf 4 years ago

        On the other hand, in a roaring twenties cheap solar scenario, 25% of Australia’s deserts, could supply, a trillion tons of liquid hydrogen per year, making the mining boom, look like a small business. Saudi Arabia levels of tax revenue.

        • nakedChimp 4 years ago

          If you do anything, do methane, but drop hydrogen. Really.

          • stucrmnx120fshwf 4 years ago

            A new option is opening up, liquid silicon, with infra red photovoltaic. But I still say liquid hydrogen is better for transporting energy, in bulk, 100,000 tons or more. Or as lightweight aviation fuel.

          • neroden 4 years ago

            It’s all gonna be solid state. All of it. Australia could be making silicon wafers…

          • stucrmnx120fshwf 4 years ago

            Being sarcastic and synical, oh no we should keep Hazelton, as a brown coal powerplant. 25% of the Australian desert, could allow us to export a trillion tonnes of liquid hydrogen per year. But no, let’s burn geologically dried excrement, even black coal, is too clean. Solar is getting cheaper, than carbon dioxide emissions based power, but on the basis of right wing dogma. Let’s not sign the Paris Climate Change Agreement, because were Australians, we don’t want to live like Saudi Arabian sheiks. Everyone else, can see huge bucks in this, but when something comes along, that’s a hundred times better than a mining boom, we run away and hide.

            Solar farms, on agriculturally useless land, making Aborigines the richest people in the world, no, no. That’s greenies, if cheap storage, cheap solar, 1/10 th the price to maintain and fuel, electric vehicles are available, let’s hide our heads in the sand and let everyone else make the money.

    • jeffhre 4 years ago

      That accounts for 18,250 KM per year per car.

    • stucrmnx120fshwf 4 years ago

      Well Elon wants to crank the factory from 1GW per year, to 10 GW per year, because the old Powerwalls, have already been such good sellers.

  12. Miles Harding 4 years ago

    Great work, Bruce!

    I was thinking that it must have got very close with this week’s announcement.

  13. BeyondZeroEmissions 4 years ago

    Thanks for the article Bruce. We’re pretty curious to hear about how readers see electric vehicles coming into the equation for the range of solar-battery-ev situations that are or will be out there – or should be … The drop in battery costs certainly should flow to cars and bus batteries. and augers well for our low cost – cost-neutral EV shift scenario bearing out. http://bze.org.au/electric-vehicles-report/

  14. Richard Koser 4 years ago

    This might be the shake-up the battery industry needs.

    Battery prices were too high, because volumes were too small. Gigafactory. Ka-boom! Tesla win the Li-ion segment, okay? They make batteries for their own cars, so they’ve got a built-in advantage.

    The relative pricing was a bit silly. 88kWh of Tesla Powerwall storage = $120k. 88kWh of Tesla storage and a car to go with it = $170k, for a Model S 90D.

  15. Phil 4 years ago

    This is why Tesla stated at the launch that the Powerwall 2 is recommended MOSTLY for non Hardwired uses such as powerpoints and lighting

    Here is a typical 240v electric cooktop power consumption. These are a wired in appliance


    Chef brand cooktop Model CHC744BA 4 zone ceramic 2 x 1800 and 2 x 1200 elements = Total Load = 6kw


    The powerwall 2 can not power this without an active grid connection
    i.e if the grid connection fails ( a power outage) The consumer will only be able to use some of the hotplates.And the electrical standards of Australia may not allow this partial operation for obvious reasons of overloading the inverter

    Perhaps 2 or 3 Powerwalls in Parallel though can power it over a single phase. ie the inverter outputs are in a frequency and phase locked mode and combined

    • Mike Dill 4 years ago

      In a grid-down, I would not expect to be running all 4 hobs at once. Keeping the lights on (at night) and the freezer running (during the summer) should be enough, along with one hob (or a microwave) for the hot meals.

      • Phil 4 years ago

        Yes that is what 1 Powerwall is designed to do

        In this case the Microwave is a plug in appliance and the hardwired stovetop

    • Ian 4 years ago

      Does anybody ever cook with all hotplates on full power at the same time?….. more typically 1 or 2, maybe 3, at part power

      • Phil 4 years ago

        Many Consumers with a family have at least 3 going. Thats 4.8kw which leaves you 200 watts for other stuff if you have one powerwall. Switch the 4th one on to do some gravy and bang the whole system shuts down

        Unlike OFFGRID systems where consumers are aware of power limits , most if not ALL ONGRID users do NOT understand limits. They expect to flick a switch and it ALWAYS works. If it doesn’t then your product or the installation is 100% crap in their view and they will tell 100 others JUST THAT FACT !

      • stucrmnx120fshwf 4 years ago

        When I retired, I moved into a smaller house, with renovated seals, roof insulation, use LED light bulbs, LED screens, including Super low drain mobile devices, reverse cycle indoor outdoor heating. Installed insulated curtains, use a microwave for all my cooking, with gas charges, at my old big drafty place, I was paying $25 a week, for energy, I cut that to $22.50. The Bill came and it was $120 in credit, so for the next 9 months I’m going to pay $7 a week, because that was the winter energy bill, which is the highest where I live.

    • nakedChimp 4 years ago

      You need 10kW-15kW peak ability for a normal house to not feel any difference, your 2-3 PW2 is about right.

      Still, this unit isn’t able to take in solar pv directly, is it?
      No one mentions it, no manual to check for myself…

      It’s still a lot of losses to convert 230VAC from the solar inverter (which takes in 300-600VDC from the panels, converts it into 400VDC internally to make 230VAC itself) to the battery voltage of 48VDC (or whatever they have in there) and then back to 230VAC if needed.
      You loose 5-10% at the PW2 just for conversion.
      Same in the solar inverter.

      Where is the hybrid inverter with the following specs?
      – single unit 10kW CONTINUOUS power output
      – load output DECOUPLED from grid connection
      – output parallelizable (stackable) for up to 30kW on single phase and 90kW on triple phase
      – 400VDC internal bus that also transfers energy between same units and to car chargers (less losses)

      • Phil 4 years ago

        I assume for it to be a 1 box solution It must have an MPPT solar charger inside as well as grid ( or genset for off gridders) battery charge capability

        They likely run the batteries at closer to the solar dc volts of say 300- 400 volts

        Efficiency should be around 95%

        • Kenshō 4 years ago

          From memory of looking at circuit diagrams in the past for PW1, I think the previous inverter was designed to be wired in parallel to the battery, so the PV strings, MPPT inputs on the inverter and the battery all operated around a nominal 450V (from my vague memory). My understanding is, the advantage of this design is the PV strings can feed the MPPT inputs on the inverter directly – without having to go in and out of a battery. The disadvantage is the battery needs a DC to DC converter capable of upshifting and downshifting around 450V nominal, depending upon whether the PV input is cranking or not. Conventional solar systems running a 48V battery bank only need the DC to DC converter in the MPPT capable of downshifting, as the PV is always allot higher voltage than the 48V. So in my mind, a 48V battery voltage is likely to be better for smaller solar arrays. My brand of MPPT and inverter is also designed so the MPPT stays powered up when the battery is full, so the MPPT can continue cranking power to the inverter to supply the AC loads, or export excess to the grid. The problem with old designs, is the MPPT slowed down when the battery approached full charge, waisting solar power. So both the Tesla system and all the other horizontally integrated companies seem to have overcome the efficiency problem, when the solar is supplying the inverter/AC loads directly. When the solar isn’t supplying the loads, then the efficiency comes back to the efficiency of going in and out of the battery hence depending primarily upon the battery chemistry.

          • Phil 4 years ago

            It MAY also have implications for 100% off gridders in Australia in that a licensed solar installer must be used when PV string VOC voltages exceed 120v DC.
            Anything less than 120V dc is considered LV and can be installed DIY .
            This is typically multiple strings of say 3 panels with 38.5 v VOC

            We will have to wait until someone deconstructs a powerwall 2 or the installation manual is available to see what modes of operation it supports.
            I suspect multiple strings will not be an issue as it has to work with their new solar tiles on different roof angles and locations

            Although Tesla may not have 50 years Inverter experience. They have achieved results with their EV’s inverters in the last few years far beyond any other EV manufacturer in performance and volume with what appears to be pretty good reliability in a mobile , extreme temperature and vibration environment using all manner of chargers in all countries using differing voltages , frequencies , currents and quality.

            I don’t think their engineers are anything less than the best available.

          • Kenshō 4 years ago

            I’ll take a guess and say it could be good for city folk with the rooftop real estate – if the 450V battery needs allot of solar panels in series. It may not offer the flexibility that a country property or non-standard residential applications may need. e.g. if people think they may need to add another PV array later, double inverter capacity later or add a wind turbine later, they may need to plan carefully.

          • Phil 4 years ago

            I’m in the country ,100% off grid and in a high wind speed alpine area .

            Some of the Inverter suppliers have Parallel kits for their combi inverter chargers that allow multiple units to achieve higher power single phase or 3 phase.They also support wind turbine specific needs

            Wind Turbines , much like Windmills , seem to have gone out of favour for the majority (or never were in favour) except for commercial wind farms

            I suspect the reasons are mostly the cost and maintenance issues. There are mechanical spinning parts and brakes to go wrong. And they don’t tend to put a lot of peak power out , although they can do that over a much longer period when the wind blows..

            The preference seems to be to put more solar panels and batteries in to meet any load. As these are often ground mounted on angled frames it’s easy to add more capacity and they can be cleaned from the ground level.

          • Kenshō 4 years ago

            Wind turbines have probably gone out of vogue because PV is so cheap and wind is easily obstructed in many areas. If I were in a high wind speed area, I would definitely get a wind turbine because batteries are expensive and have limited life. Last I enquired, one simply lets the wind turbine manufacturer know the DC voltage of our battery bank and they supply the suitable gear. There’s also wind turbines which output AC that can be wired into the external AC input of an inverter/charger instead of a diesel generator or grid.

        • Kenshō 4 years ago

          I agree with nakedChimp, PW2 is likely to be a basic inverter (because they don’t have 40 years experience like other manufacturers) and hence the inverter/charger may not:
          a) be able to be paralleled to double or triple output power,
          b) the charger may not be available in high or low power models,
          c) the inverter may not be able to be wired for three in three phase configuration,
          d) the inverter may have limited number of MPPT inputs or no choice on the number of MPPT inputs,
          e) the inverter may only be able to have one external AC input connected, hence we chose between grid, generator or wind,
          f) the inverter may be a black box throwaway component or difficult to access or need Tesla trained technicians to access without voiding the warrantee,
          g) the system is unlikely to have a GPS feature also supplying other smart software data back to a base website, so have less appeal for yachts and motorhomes where people want to know where the system is.
          So many questions with Tesla usually being slow to release specs and usually we find they supply the minimum gear to get the basic job done for a price. In other words its basic gear entrancing people with a kWh price, from a manufacturer who is new to batteries and never made an inverter/charger.

        • Kenshō 4 years ago

          The most silly aspect of the powerwall design is the flat battery on a wall concept. Firstly another manufacturer states lithium batteries will halve their life for each 10 degree C rise in temperature, so an external install in anything facing sun is ridiculous. Secondly, garages are designed for stacking things against walls. A fridge shaped battery would have so much more power output for the floor space. The powerpack is a far superior modular design in that regard. So no Tesla have not “nailed it”. After the Tesla hype fades and other products arrive, PW2 will be a flop like PW1.

  16. Kenshō 4 years ago

    Tesla has positioned it’s battery at the top end of town. It’s not the biggest cheapest battery that gets the market share. It’s the overall most affordable in terms of accessibility for all of us to step into energy independence. That includes Africa and China. All of us have a say.

  17. Leila Blair 4 years ago

    But when I called a solar company in Tucson, Net Zero One, they said they have trouble actually getting the batteries from Tesla. That was their answer when I said i wanted the Tesla 2.

    • john 4 years ago

      That is because they are not on the market yet.

  18. stucrmnx120fshwf 4 years ago

    3 things, first your quoting the price, for installation after the house has been constructed, it already doesn’t make sense, to not install solar, at the construction phase. Then 2nd let’s consider the savings with solar tiles, they’re cheaper than solar plus tiles, plus the installation costs are even lower, than installation of solar, at the construction phase. Thirdly, Powerwall has been very successful, at the old prices and will be even more successful, at half of the price per kWh, so Elon Musk, intends that the battery plant, won’t produce 1GW of storage capacity per year. Now, he intends to eventually produce, 10 GW of battery capacity per year, with all the potential cost reductions per kWh, that a 1,000% increase in production, economy of scale brings.

  19. Kenshō 4 years ago

    We’re in a blackout ATM and in practice a small battery would be big enough to carry a residential property through a daytime power outage. The battery is 9.6kWh of lead acid batteries though during the solar day it sits on 100% charge. The reason is the sun going in is more than the power going out during the day, so the battery size in kWh is less of a factor than the amps the battery can produce to run the necessary electrical appliances in an outage. Lithium batteries are lower amps so perhaps this is why Tesla has doubled the battery size, so the amps are sufficient. That battery size is really big for a residential battery where the property is maintaining a grid connection. Many people would not need 14kWh. Even overnight, our energy efficient appliances only use 3kWh overnight, excluding heating in winter and AC in summer. Perhaps the size of the battery is for EV’s though the majority of people might charge them at home or work during the daytime.

    • Phil 4 years ago

      I think it’s the Inverter price / performance cost that is the limit along with the cooling and heating.It has to work between -20 and +50 deg celcius , that’s some thermal management required to do that

      Because the batteries run at such a high DC voltage , i’m assuming 300-400 volts dc , then thats approx 8-10 times less current than a 48volts battery system would need for the same AC output power.

      Assuming 350 volts DC average and a 95% efficient inverter at full load then the 7Kw peak output of the Powerwall 2 would be only 20.5 amps DC @ 350V

      • Kenshō 4 years ago

        On this other article, I noticed in the comments some people like the idea of an integrated inverter:
        “Rivals fear Tesla may become the Apple of battery storage
        Sophie Vorrath”

        My personal bias, having worked as an electronics technician in communications systems, is I like a modular design so if something goes faulty, I can more easily work around it. I’d rather avoid “black box” products that need specialists to service or have to be sent back to a factory – especially because in this case its a power supply. I’m also uncomfortable with the 400V battery because I can’t see manufacturers making DC appliances in the future for that voltage, as its too high making arcing a problem for circuit breakers. I was looking forward to the future where we could reduce inverter size and cost by having some DC appliances, since most appliances in a house are DC anyway. AC is good for poles and wires, stoves and washing machines. Getting the inverter cost down can also be achieved without loss of bill reduction by purchasing a small hybrid inverter, as for rare occasions a higher power electrical appliance is needed, the hybrid inverter typically can import 10kW from the connected grid anyway. In outages like the one I’m in now, I find a 2500W inverter is sufficient, as then the three of us have an agreement to only run one kitchen appliance at a time (kettle, hotplate, toaster, microwave). All the other stuff like the two fridges, computers and internet router, all works fine. Solar could be so cheap and simple if engineers only wanted to make it available without upselling.

        • Phil 4 years ago

          Yes that’s easily fixed with Tesla , Run 2 or more in Parallel and if one fails you still have backup , albeit at a reduced load. .Then get them (Tesla) to fix it under the 10 year warranty.

          And because it’s one brand and one fault indicated ont he one device the consumer does not have to think about who to call to fix what

          Many off gridders do the same now , i certainly do as i have 2 of everything except batteries.

          I think Tesla have “nailed it” as the complete vertically integrated solar solution that must and has now happened.Nothing can stop them now.

          Re DC appliances , i cant these happening soon as the manufacturers would have to make an ac and dc or ac/ dc model , and this adds cost
          You only have to look at the RV market which uses them to see that

          And with motor driven appliances now almost completely going soft start AC or DC inverter drive then the losses and peak and average loads using AC are far less each year.

          And now we can have such affordable big inverters and batteries a little loss is minimal compared to the money saved buying appliances that millions of others also buy globally. Just whack an extra solar panel in to make up 5% loss !

          Even the swimming pool filter pumps and water pumps are mostly full inverter drive now.

          • Kenshō 4 years ago

            I think off grid systems warrant having two seperate inverters with different solar arrays, to have that redundancy built in. For people with a solar system where they are maintaining a grid connection, I think one inverter is sufficient. The big environmental and humanitarian issue is people being able to step into solar for the lowest cost. e.g. the basic mathematics of my system with top quality brands is:
            PV $2k
            9.6kWh Lead Acid batteries $2k
            2500W inverter/charger $2k
            another $1.5k for monitor, wire, breakers etc.
            You appear to be arguing in favour of Tesla. I’m not committed to any brand. I go where I like the specs for the money and my purposes. Most of the solar system equipment is simple to wire and any electronics technician or electrician should be able to service it by lifting out one piece of equipment and sliding in another. Horizontally integrated companies like those in the android platform are more likely to reduce price for the longer term. When it comes to private companies upselling, competition is good to bring the price down.
            The RV market is small comparatively though in the future the residential market will undoubtedly move to DC appliances as it reduces the need for an inverter and makes the system more fail safe, especially valuable for rural people. Options and simplicity are great.
            Yes true, soft start compressors in fridges and microwaves running DC inverters, are making life easier on the solar inverter, reducing its peak power and not having appliances cut in and out as often, all increasing longevity of the inverter.
            I challenge you to think in a more humanitarian way, beyond whatever socio-economic group you reside in and think of the billions of people worldwide, who need the smallest stepping stone entry into solar power and a measure of energy autonomy and independence. Tesla are a chronic upseller with their sales approach. Always bigger. Like buying a bigger can of food. Buy this and we’ll give it to you this much cheaper.

          • Phil 4 years ago

            Based on your comments the individual component system suppliers will have plenty of healthy sales still to those who cant afford a Powerwall 2

            Everyones a winner