Tesla Kills Off DC Powerwall 2. AC Powerwall Delayed

powerwall 2 DC is dead

DC’s not pinin! DC’s passed on! This battery system is no more! DC has ceased to be! It has expired and gone to meet its maker! DC’s kicked the bucket! DC has shuffled off its Tesla coil, run down the charge, and joined the bleedin’ choir invisible! THIS IS AN EX-BATTERY!

I was just relaxing by listening to the musical version of the Massacre of Mankind when I suddenly got some news from the solar grapevine1 concerning the Tesla Powerwall 2.  To cut a short story even shorter:

The DC version of the Powerwall 2 is dead!

Long live the AC version!

If it ever gets here!

In response, I immediately leapt on the Adelaide internet and started furiously tugging on the string that sends ones and zeros to contact my contact at Tesla, who immediately replied, but insisted on remaining an unnamed source.  So for now I’ll just call him Secret Sauce, which at least is a better name than Deep Throat.

Tesla’s Unofficial Response

His (or her) response was the following:

Tesla is committed to the development of industry-leading technology and ensuring we always provide our customers with the best products possible. The AC Powerwall includes a Tesla built-in inverter, offering customers the greatest value, flexibility, and ease of installation, regardless of whether they’re pairing Powerwall with new solar, retrofitting, or using the Powerwall for backup. As a result, we will no longer be offering the DC Powerwall, which was the same price and size of the AC Powerwall but did not include an inverter.

 

When Tesla originally launched Powerwall 2, we announced we would offer an AC Powerwall and a DC Powerwall. Both variants cost $8,000 and are identical in size. The only difference is that the AC Powerwall included a built-in inverter, offering customers the greatest flexibility for retrofits, standalone, back-up, or new solar without the need for an external, compatible inverter. The DC Powerwall would only be used for customers who already had an existing compatible inverter and therefore didn’t need an integrated inverter.

So, Tesla is committed to ensuring they provide customers with the best products possible.  But not ones they’ve actually promised to deliver.  Because apparently the AC version is superior.

You know, if the AC version of the Powerwall 2 is so much better than the DC version, you’d think they could have worked that out before they started taking people’s money, wouldn’t you?

The real reason for having both an AC and a DC version is they are two quite different things.  If I wanted to add on-grid battery storage to a home then the AC version of the Powerwall 2 should be an easy way to do that.  But if I wanted on off-grid installation I would use the DC version of the Powerwall 2 along with a compatible multimode (hybrid) inverter.

But even for an on-grid installation there are good reasons for wanting a DC version.  For one thing, DC coupling batteries can result in higher efficiency and lower losses than AC coupling.  It can also simplify monitoring the system.  And another reason could be avoiding red tape from electricity distributors.

Update: Tesla have advised that full monitoring of the battery and solar via a Tesla app can be achieved with an additional “Tesla Gateway”. No word on the price. From what I can tell, it will need to use current transformers to monitor the solar and consumption on non-compatible solar inverters.

Network Operators Could Prohibit The AC Powerwall 2

Many Australian households are limited to installing a 5 kilowatt solar inverter2, or a total of 5 kilowatts of smaller inverters.  It is possible that your electricity network operators could declare that the inverter in the AC Powerwall 2 counts towards any maximum solar inverter size and so effectively prohibit it for most households, as they would be forced to choose between having rooftop solar or an AC Powerwall, as it has a 5 kilowatt inverter.

Counting a battery inverter as adding to solar inverter capacity is completely nuts as it does nothing to increase the output of the solar system it is attached to and battery systems improve the operation of the grid, so I don’t believe this will be done.  But, I also didn’t believe Trump would become President, so what do I know?  People could definitely prefer to have a DC Powerwall 2 rather than an AC one in order to be safe rather than sorry.

The AC Version Will Allow ‘Full Home Backup’

Secret Sauce still stands by Tesla’s claim that:

The AC Powerwall will provide full home backup“.

Just please be aware that ‘full home backup’ is a very different proposition to ‘operating off grid’.


Technical Notes from Finn about the difference between ‘full home backup’ and ‘off grid’:

Full home backup

Full home backup is simply using energy from the batteries to power the home when the grid is down. Crucially this usually does not include charging the batteries from the sun if the grid is down. In a grid outage you can’t use the grid to absorb excess solar when the batteries are full. So when your battery is full you must reduce the amount of solar produced to balance with your home’s demand. But AC coupling makes it hard or impossible to tell the solar inverter to throttle its output. It can be done with managed AC coupling, but you need a specially designed, compatible inverter for that.

Off grid capability

Most folks who ask for ‘full home backup’ expect that, in a prolonged grid outage, their batteries will recharge from the sun to extend the time they can operate ‘off grid’. A retrofitted AC coupled ‘home backup’ system usually can’t manage this. If your batteries go flat, you are out of luck until the grid is restored, even if the sun is beating down.

To safely charge the batteries without a grid connection the AC powerwall will need a special, compatible solar inverter (which does not yet exist). The only alternative is to use a really coarse form of control called “bang bang control” that switches your inverter on and off instead of throttling it. This is not good for the solar inverter and may void its warranty, so I can’t see this happening either. 

In other words don’t expect to run fully off grid through extended blackouts with an AC Powerwall.


 

Households, Installers, And Inverter Makers Stiffed By Tesla

The DC version of the Powerwall 2 was not just a vague idea of Tesla’s floating around in Platonic battery space.  It was an announced product that they said they were going to make.  I even had my picture taken next to a big hollow Powerwall 2 case they put on display.  (I can tell you, I am taking the poster I had made of that down off my bedroom wall.  I don’t care how arousing the wife finds batteries.)  They produced datasheets, gave prices, and took deposits on god knows how many thousands of units.

The people who paid those deposits are quite justified in clenching their fists and growling between their teeth, “We had a deal, Tesla!”

I am certain the home owners who paid deposits will get their money back.  Either that, or Tesla will manage to convince them to switch to AC versions.  So they will get off lightly.  But some people have been screwed so severely by this they may end up looking like a walking mass of Phillip’s heads.

Firstly, there are the people who paid to install a StorEdge multimode inverter which was compatible with the now non-existent DC Powerwall 2.  There are installers who paid for StorEdge inverters who will now have stock people are unlikely to want.  In addition, they also paid for training on how to install them.  And then there is the SolarEdge company itself, which has made a line of inverters that are basically meant for use with DC Powerwalls.  I bet they’re not happy about this at all.  It will be interesting to see how much their stock will have dipped by the end of trading tomorrow.

What You Can Do

If you have put a deposit down on a DC Powerwall 2 you can ask for your money back.  And if you’ve put down money for an AC Powerwall 2 you could ask for your money back if you no longer think Tesla is a company you can trust to deliver what they say they will.

If you have installed a StorEdge inverter in preparation for getting a Powerwall, don’t panic too much.  LG Chem produces the RES7H and RESU10H with 6.6 and 9.3 kilowatt-hours of usable storage which are compatible with it.  I’m afraid there may not be any other battery systems that are compatible on account of how the voltage range Tesla Powerwalls operate at is a bit odd.

You could also get an AC Powerwall 2 and AC couple it to your home.  This means your fancy and expensive StorEdge inverter will just act as a plain old ordinary one and won’t have anything to do with the functioning of the Powerwall 2.  I do not think this option would be suitable for off-grid use.

If you are an installer who has bought a heap of StorEdges you now no longer need, I guess you could try to convince people how great the higher voltage LG Chem RESUs are.

And if you are SolarEdge, the company that makes StorEdges, then I don’t really know what you can do.  But I can tell you you definitely should not hire Ninjas to wreak revenge upon Tesla.  Because that would be wrong.  Also, revenge will leave you feeling hollow inside, just like an empty Powerwall 2 display case.

AC Version Delayed

Tesla are now promising the first Australian customer installs will be in late April3 – 2 months later than originally promised.

What The Hell Is Going On?

So why did Tesla cancel the DC version of the Powerwall 2?  I’m afraid I just don’t know.  But if I were the kind of person who speculates wildly, and I am, I would guess Tesla simply bit off more than they could chew.

If they can get the AC version to work there is potentially a huge market for AC coupled battery storage.  I think they decided to concentrate on that, saw the DC version as a distraction, and so threw it under the bus and and walked away, turning their backs on everyone who gets hurt as a result.

But don’t listen to me, I don’t know anything.  Go bother Elon Musk for the true story.  If he knows it himself.

Footnotes

  1. All grapevines are technically solar powered if you think about it.
  2. Or if they want to install more than 5kW they have to jump through a lot of hoops and risk their application getting knocked back anyway
  3. Originally we wrote June – Tesla have since pinky promised us that the first installs in Australia will be in late April. We’ll see if that happens.
About Ronald Brakels

Many years ago now, Ronald Brakels was born in Toowoomba. He first rose to international prominence when his township took up a collection to send him to Japan, which was the furthest they could manage with the money they raised. He became passionately interested in environmental matters upon his return to Australia when the local Mayor met him at the airport and explained it was far too dangerous for him to return to Toowoomba on account of climate change and mutant attack goats. Ronald then moved to a property in the Adelaide Hills where he now lives with his horse, Tonto 23.

Comments

  1. I’m sure some enterprising people will work out how to bypass the inverter inside it……….

    • Jack Wallace says:

      Sure they will DJR……And some rather cleverer people will work out how to bypass the whole unit. Of course, given the way the world works these days, it might cost a bit more……..

  2. Ronald, what about Enphase’s AC Battery? At least they envisioned home energy storage years in advance and came out with an integrated storage solution for the masses. It looks like Tela followed their lead and Osborne’d the Powerwall 1 customers and burned their inverter partners, too. Storage is still an expensive proposition for most, so it is important that there is an actual ROI. For the most part, the only logical reason for getting storage right now with ROI in mind is to “save” the value of the excess electricity your solar PV system generates — this is why with FiTs and NEM ending, the Enphase AC Battery product is selling well in places like Australia, New Zealand, the UK, and in parts of the USA now. Scientifically, its the 1st kilowatt that gives your the best payback on storage, and that’s what Enphase focused on with their modular 1.2kWh battery; they wanted something to appeal to the masses. Furthermore, they chose one of the safest battery chemistries to use, too — LiFePO4.

    • Ronald Brakels says:

      With the recent “restructuring” at Enphase, which is what they called sacking 18% of their workforce, I thought the Enphase AC battery might get thrown under a bus, but that doesn’t seem to have happened at the moment. Unfortunately, its economics are worse than that of the increasingly imaginary looking Powerwall 2. In order to be economically worthwhile, a battery system has to at least save a household more on their electricity bills than they’d make in interest if they’d left the money in the bank and the Enphase AC battery definitely can’t do that at its current price. At the moment, large rooftop solar systems and energy efficiency measures are far more cost effective and for getting through blackouts the best option for most people at the moment is to either get a small generator or just put up with them.

      I looked into the Enphase AC battery here:

      https://www.solarquotes.com.au/blog/enphase-batteries-are-impressive-but-very-unlikely-to-save-you-money/

      • OK, pricing here in the USA is about $1.54 USD / Watt. A lot of Americans will buy it to fine tune their solar PV systems so that the excess electricity they are generating is not given to the likes of your Warren Buffett’s and the utilities he owns (NV Energy). I am just using Mr. Buffett as a figurehead, but the energy monopolies are starting to push outrageous grid-connect fees (Arizona Power Systems pushed for $120 USD / month just to be connected to grid!!!) For most small solar systems < 7kW, a few Enphase AC Batteries can save the customers value instead of giving the electricity away for free to the utilities. I'd like to see pricing here in the USA get down to $999 though — I think people would buy the AC Battery in droves, then. Although it is pricey now, the modularity and safety of the AC Battery is still attractive. It offers the same reliability concept of the microinverters. The CEO of Enphase said that storage today is where solar was back in 2007, so the market has a ways to go. I feel sorry for all those Osborne'd Powerwall 1 users and Tesla's inverter partners, and now this latest news with the PW2. Tesla is building quite the reputation. Great article. Cheers!

  3. Jack Wallace says:

    GEE!!…….Who’da thunk?

  4. Im trying to work out where that leaves us poor sods who have the Fronius Hybrid Inverter, actually any hybrid inverters to be fair.
    Back to the drawing board for me it seems.

  5. smithy2167 says:

    Will the AC version become AC/DC?

  6. Graham Alexander says:

    It’s early days everyone. It will happen. Soon.

  7. PR suicide!

    I wish they would of just released a bottom balanced battery with some kind of monitoring to prevent over or under charging able to be easily and most of all cheaply installed with most systems.

    And perhaps a smaller cheaper pack that could be added to later to lower that barrier to entry to encourage mass adoption.

    Major bummer!

  8. Here in the USA , it’s possible UL will never certify a system to UL 9540 with Metal Oxide Batteries. ie.like the Tesla/Panasonic NCA Recipe. The Enphase is LFP or Lithium Iron Phosphate Batteries are considered stable and unlikely to Chernobyl when abused. LFP are also the only Lithium Battery allowed on Boats. You guys downunder are lucky that you have 120Vdc systems. The Codes and Utilities have 50Vdc as max Stateside. One can 100-400Vdc PV Direct into select Meanwell HLG type A ( read the International spec sheet ) to charge a matched/fused Li Bank or you need no Battery at all. Not yet approved for Solar use – but works great.

  9. I’ve sold 60+ SolarEdge inverters in the past 4 months.

    That’s 60+ batteries that TESLA isn’t going to sell.

    LG must be laughing.

  10. I actually don’t think this is as terrible as you make it out to be. Sure the DC one was like 2% more efficient, but they really only screwed with one inverter manufacturer and that’s Solaredge. You’ve previously posted articles saying Tesla is the new apple and they’re killing inverter manufacturers – well the AC powerwall works with any existing solar system, so this has actually helped competition out there, instead of partnering with one manufacturer (Solaredge).

    I almost had a Solaredge installed, they do have other advantages besides being Tesla compatible – if your roof has potential shading during parts of the day, the power optimizers on the Solaredge system are a life saver… so people will not necessarily be as angry as you make them out to be, just because it won’t be DC coupled. The Solaredge inverter will still have all the other advantages, but it’ll just be AC coupled, big woop.

    • The Storedge inverter is considerably more expensive than the standard Solaredge. That’s money wasted for no advantage for those set on getting a DC Tesla 2.

  11. Gary Looney says:

    Tesla have been screwing me over since filling out document of interest to buy and distribute the DC Powerwall, directly after the first announcement of intention. This is Tesla costing the public millions in stagnation and deposits.

    Tesla has disregard and contempt for the public’s time, money and energy.
    Tesla is ruthlessly driven by profit, ready to send others to their deaths on Mars, not an environmentally concerned company in any way, shape or form.

    After waiting years for agreement with Tesla, and receiving another letter 28 Feb 2017, Powerwall installation starts soon.

    Let’s start a class action to recover the money Tesla has cost us.

    Gary Looney
    Menindee

    • Amen, Gary Looney. Musk’s cars are kiiliing people and getting away with it; he doesn’t care if humans are used as test guinea pigs to sell his junk — caveat emptor! Musk was in Davos in late January with fellow globalist ChiCom’s Xi Jinping touting that the world needs to merge with the machines and those who don’t will become irrelevant — and Xi, well, he’s taking HRC’s position leading the globalists, the Bilderbergs, since $1B and controlled media could not get her elected. I wouldn’t spend one bloody dime on Tesla, because he is not for the common people, or as you people in the Land Down Under would say, the common blokes.

  12. Don’t know why but I have a feeling that Mr Musk is more interested in escaping from planet Earth than actually hanging around to see the results of his works.

    • Mr Musk does not want to hang around, because he knows that him and his millionaire buddies are getting rich by trashing the the planet and screwing little people like me. He wants to build space travel so he and his wealthy buddies can escape the apocalypse while the rest of us have to live on a dead planet in his borg collective.

      • ROFL and Mars is not a dead planet? Far deader than earth. Do you have any idea what it would be like living on Mars? Check out the facts! I do not even anyone that would want to live on Mars their whole life. Maybe a visit would be nice but to live 24/7/for years. Not for me.

        As for Musk he is “helping the little” guy more than you realize. He is brining the cost of battery storage down to where it will be less expensive to NOT to be tied to the grid than tied to it in less than 10 years.

        The grid is nothing but a money machine for utilities no matter what country you are in. That has to stop and in the long run is awful for our planet.

  13. athomas says:

    Won’t the AC version need to meet AS/NZS 4777.2:2015 standards?
    It’s currently not on the list of approved devices.

    • Guy Stewart says:

      Correct, and considering the delays that other companies (eg SMA) have had in getting this certification, Tesla is making promises that may be out of its hands to keep regarding installation dates.

  14. Solar Edge announced a 48Vdc SCC in 2014. Vaporware. What about – NCA.Metal Oxide Li Chemistry not appropriate for stationary eChem Energy storage do people not understand? We want our bleeping PW and we want it NOW, but it’s like the Gadget in 2001 A Space Odyssey! What chance a PW cycles 7800 times @ 90% like enphase warranty ?

  15. Claude Feller says:

    Thanks a lot for this!
    Being a solar installer I have more and more requests for the fancy PW2 but unable to answer.
    For off-grid is there any way to add the PW2 to SMA off grid setup with Sunny Island and Sunny Boys? I dont see that the PW2 has been approved by any battery inverters so far.

    • Ronald Brakels says:

      Hi Claude. My impression is Tesla is going to keep tight control over all the AC Powerwall 2s installed in Australia. So if you were able to get your hands on one to try what you suggested, I suspect Tesla would say it would void its warranty.

      • Claude, myself and many others are very interested to know the answer to Claude’s question – how can one enable an off-grid system using the PW2 given an existing install using say an SMA inverter.
        So if anybody comes up with an answer, we would appreciate a reply to this thread.

        Thanks,
        PJ

    • My understanding is that the whole point of an AC PW2 is that with the built in inverter it can be added to any AC installation whether that be on-grid/off-grid, and with or without solar PV. It is independent and thus should have the flexibility to work with any other solar inverter system.

      • Claude Feller says:

        If it is so much flexible then it must have both BMS and battery inverter integrated inside the PW2 casing. Well, if the battery is 48 VDC there will be a lot of heat to be managed….

        • Yes, all-in-one unit.
          The datasheet for the AC version states the battery is 50VDC. Which I admit is a little surprising because the Solar Edge inverter shows the DC version is connected in parallel with the PV array – between 400-500VDC. So I would have thought the AC version would have been the same and not had to transform the voltage as much in the inverter.

          Both AC and DC versions would have proper BMS systems.

          The voltage is not really going to make any difference to heat. All it means is lower voltage = higher Amps and thicker cables. Heat is inversely proportional to efficiency. More efficient = less energy wasted as heat.

          • Claude Feller says:

            Every Lithium battery is producing HEAT. Every battery inverter is producing HEAT, especially when they are supposed to supply 5 kW or more of loads. So if you put the battery and the inverter in the same “box”, you will have a serious heat problem. I mention this bc we are working here in Thailand and we have a lot of heat already.

          • DJR

            I think that the battery voltage in the PW2 AC is a battery of 50V DC for individually battery modules and NOT the operating inverter voltage. I think that the inverter is a high voltage inverter because the DC input from your PV array is high voltage as I understand it. Of course I will need to contact y source at Tesla to get more information about the inverter and if the PW2 has a MPPT charge controller integrated into the inverter.

          • Thanks John. We’re keen to see what more information you can obtain.

            And yes, modules may well be 50V and there could be 8 modules in series to get to 400V. Would be nice to have a close look inside one…..

  16. Leigh Phillips says:

    I mostly work in Ausnet service distribution area and 4.6kw solar not AC input is max they allow on single phase without jumping through a bloody commando obsticale course to get approval for a larger array, looking customers with this size system average 2 + 2,family mum at home there really is not sufficient excess solar to charge a fully discarded 14kwr battery, mostly seems to suit lg chem battaeries. Also no 3 phase option on a battery this size, madness

  17. I aslo have a contact at Tesla. I was told the DC Powerwall will not be available till maybe mid summer. So I do not think it is dead at all. I live in Colorado

  18. Re: PW2 inverter:
    SolarEdge’s inverters are ‘transformerless’. Attached devices can’t be grounded, and may be live. Tesla produce the same battery ‘pod’ for the Powerwall and the Powerpack. The module contains the cells, and an ‘isolated’ DC/DC converter, which would allow safe connection to the transformerless inverter. That is what they did for the PW1. Additionally, the converter allows output power control.

    But, new regulations say:
    “Stand-alone inverters with connection ports for ELV batteries must be isolated type only. The CEC will not list non-isolated (transformerless) stand-alone inverters, as these do not comply with the installation requirements of AS 4509.1 (refer to Clause 9.3.3).”

    Not sure if that’s a problem or not.

    Anyway, the internal battery is ~50VDC, where the pod’s converter raises the voltage to 400V for connection to the battery port of the external inverter.

    The AC version’s internal inverter ( outputing 240V AC) may take either 400V from the pod’s converter, or 50V directly from the cells.
    Could be either way, but Tesla like to keep all of the pods to be the same, and all are low voltage internally.
    As far as I know, there is no PV input, but is an AC-coupled battery.

    • Interesting. 1st of all the D.C. to AC (120-240V)! That Tesla makes that is part of the PW2 is definitely tranfirmoless. If you look the picture on their web it is very small. Besides a tranfirmerless is definitely more efficient than a transformer type. This is why more and more inverters are being made without the transformer.

      As to what voltage that inverter runs on is unclear. I do not think it is going to be a dual voltage inverter. Never seen one of those before. Where is your 400 v D.C. coming from? Your PV array? There has to be some type of voltage regulation build in somehow to charge the battery from the grid or from the PV array. So one question remains. How do you hook up a PV array to the PW2?

      From talking to the Tesla Rep he told me only two inverters work with the PW2. The solar edge and the solar city which is just a rebranded Solaredge inverter. That means there is no charge controller in the PW2 at all. The PV array goes through the AC grid tie inverter and goes into the PW 2 as high voltage D.C. Then the inverter in the PW2 converts the D.C. to 120-240v AC. Thus I still think the inverter does not run off of low voltage D.C. (50v). I believe that the 50v modules are put in series to get high voltage to the inverter. Makes no sense any other way IMO.

      • Phil Hapgood says:

        While transformerless inverters have less loss, this comes at a price, Surge rating. This may not be a problem if the grid is there to assist but in an off-grid situation, having a hefty surge rating is very necessary.

        • not true. i have seen transformer less inverters get 3 x the surge rating. for example a 5 kW inverter can serge to 15 kW. things are a changing!

  19. most transformer inverters surge 2x their rating. so if you have a 4 kW inverter the surge is 8 kW.

  20. Wow I recently just received my $990 for a PW1 returned from a solar installer company in Oz and then put it ondirectly withTesla for PW2.
    But want it to be used when the grid fails by acting as a off grid system. ie recharge from my pvc.
    So this is a pipe dream?
    I think I should get back my deposit back from Tesla and sit tight as there’s obviously much to be decided by regulators, and the manufacturers so retailers and installers can actually know if they lied or not!,, 🤡

  21. Been doing the rounds and have come up against a brick wall. Apologies if this may be on the wrong forum but it ties in with this one anyway.
    I initially wanted a PW 2 but have decided a much more sensible out come would be to buy an LG RESU 6.5 Chem battery to pair with 8 kW of LG Neon 330 panels.
    I want to try and avoid string inverters and use a microinverter system. Not sure if I need a conventional inverter to get energy into the battery as microinverters have their own as I understand.
    So here is the brick wall: Enphase produce microinverters but only for a maximum of 280W per panel. The LG panels produce 330W max on an ideal day so the energy production will be clipped. It seems pretty dumb using these panels for an output no better than dodgy Chinese panels.
    Can anybody suggest a way around the conundrum? Thanks.

    • Ronald Brakels says:

      Hello Mick.

      While LG NeON 330 watt panels can output 330 watts under excellent conditions, this very rarely happens. As a result very little will be lost from using an Enphase S280 microinverter and a 330 watt panel than if you used a hypothetical 330 watt microinverter. I wrote about this here:

      https://www.solarquotes.com.au/blog/oversizing-solar-arrays/

      Despite its name, the Enphase S280 is rated for 270 watts of continuous AC output. This means a 330 watt panel will be 1.22 times its capacity. This is within the 1.33 limit and the amount of lost output this results in should be insignificant.

      I will mention, probably unnecessarily, that as microinverters provide AC power, any batteries you get will need to be AC coupled.

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