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Converting to Powerwall 2 off grid

Discussion in 'Tesla Energy' started by Sodamo, Oct 30, 2016.

  1. Sodamo

    Sodamo Retired and busy :)

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    Just signed up for 4 of the new Powerwall 2. A lot I don't know, but appears not a lot of published info available so hopefully signing up will lead to an informed decision. Would really like to learn how to integrate these batteries.

    Currently live totally off grid on the Big Island of Hawaii.
    Current system is 48v based on Outback.
    10kw PV
    3 Flexmax 80 charge controllers
    4 FX3048T inverter/chargers
    12 Roll Surette 4vdc batteries - 48vdc 1350ah
    2 diesel backup generators

    Average daily use approx 28 kWh
    Average daily PV production range 10-40 kWh/day depending on weather.
    Batteries and base system approx 10 years old so I know replacement batteries are in my near future, hence my interest.

    First concern is how do my PV connect to the Powerwall? Will I need a separate charge controller? If so, are my Outback CC compatible?

    I assume that with depth of discharge I most likely will not need my Generators except emergency or extended low charging days. Can my generator be integrated? Would be great to never have to use, but comforting to have in beginning.

    Is there a remote monitoring app?

    Is there mo info/manuals etc available online?

    Anyone aware how I can do a self install? Had to agree to installation to signup, but in reality I've been maintaining/updating this system myself since initial install. If I were to stick with present system, I'd be replacing the batteries myself.

    Thanks for any input.

    David
     
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  2. NOLA_Mike

    NOLA_Mike Grouchy

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    I have no answers to any of your questions but want to follow the thread in case anyone else does... :)
     
  3. SageBrush

    SageBrush Active Member

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    Subscribed.
    Good luck!
     
  4. Ampster

    Ampster Member

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    I have a 48v Outback Radian inverter that runs on 48v like yours. From what I understand about the original Power wall is that it ran on a high voltage DC bus (about 300v) and I couldn't figure out how to get those two to work together. I understand very little about PW 2.0 but it appears that it may have a built in inverter. That means you might be able to "AC couple" those systems using the AC bus. Outback has good architecture to accommodate AC coupling.

    Since you are considering self install have you thought about a simpler integration of Lithium batteries into your existing syste. If you are not on the Outback Mate3 that would give you remote monitoring. I just bought a pack from a crashed Nissan Leaf for under $2000 which was under $100 per kWhr. Food for thought.
     
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  5. Sodamo

    Sodamo Retired and busy :)

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    Last time I checked, to replace my current batteries with same would cost me twice what I originally paid or over 20k, hence my interest in new, alternative, especially Lithium batteries. Unfortunately, until the PW 2, all the choices have been cost prohibitive. A neighbor recently went with Sony lithium, but she has a smaller system and even using my existing Outback stuff the cost would be approaching $40k assuming like capacity. Finding suitable car batteries locally quite a long short but would be nteresting.
    Yes, I do have Mate 3 with OpticsRE. During a recent trip to Europe I was able to monitor and control my system via internet with little concern for my housesitters expertise.
    As I understand the PW2 info, the self contained inverter would allow me to completely bypass my Outbacks, would be great if I didn't need the FM80s as well. To replace my current batteries and perhaps get new hardware for little more than than cost to replace my current batteries is attractive. The fact the Lithium batteries my last my lifetime (70 next month) even better.
     
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  6. miimura

    miimura Active Member

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    Outback is actively working on a next generation system which will function like a Radian, but with a high voltage DC battery bank. They will also have built-in solar charge controllers. They are taking their time to get the product right and want to simplify installation, much like Tesla intended with PowerWall 1.0 to 2.0.

    I would like to build a system with two salvage Leaf packs (or similar capacity from other EVs) and an inverter like this. I don't have a problem spending $5k on a 8kW inverter when I can get 40kWh for just another $4k. The goal is to get 8kW & 40kWh for below $10k. That is less money than two PowerWall 2.0 units and 43% more energy.

    As for the OP's situation, I'm sure Tesla Energy will be able to handle your situation. However, I would expect only the solar panels and wiring to carry over. You will probably end up selling the Outback inverters and charge controllers. Interfacing to the generators is an obvious need, so they should have a solution for that too. PowerWall 1.0 has a nice app and monitoring system, so PowerWall 2.0 should be the same.
     
  7. electracity

    electracity Active Member

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    If the AC powerwall 2 works as expected, that might be the simplest solution because it uses you existing equipment. Hopefully the AC powerwall is not intend solely for power backup when the mains are down. An AC powerwall should be chargable from a genset. The regular DC powerwall probably is not. The charge controller is most definently in the powerwall. I have read conflicting information as to whether the DC powerwall contains a solar inverter.

    Powerwall 1 needed power optimizers on the panels to provide constant voltage. We don't know what powerwall 2 will require, but it is almost certainly in the 350v range.

    It may be a couple years before they have multiple powerwalls working off grid.
     
  8. Sodamo

    Sodamo Retired and busy :)

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    miimura
    How would you charge those packs? A charge controller? What one? Just trying to get knowledgeable. I know how a conventional off grid system works, but so far at a loss here.
     
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  9. Utahken

    Utahken Member

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    I can guarantee to you that Tesla won't allow for a self install. You must use their certified installers. It is a shame, but that is what they want. Not much is known how the PW version 2 will charge yet. Solaredge technical support mentioned that they are working on the control software for this version also, but I am not confident in that. If it is true then it would be charging on the DC side. I think Tesla added the inverter to simplify installation and maybe to charge the batteries too so it would be bidirectional. Need to wait for more answers.
     
  10. SageBrush

    SageBrush Active Member

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    Judging by the gouging stories we here about Tesla certified electricians, that is not going to help sales. With time I'm sure the requirement will be waived or the customer will be given the choice of skipping the Tesla warranty.
     
  11. miimura

    miimura Active Member

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    People have used salvage EV packs with existing off-grid inverters. However, the inverters are the traditional 48VDC nominal systems like the Outback Radian and SMA Sunny Island. In that case, you have to break down the pack and arrange the modules into a new serial-parallel arrangement that stays in the 40-60VDC range. With the Radian you would use their solar charge controllers, similar to what you have. With the SMA, you would use their normal SunnyBoy grid tie inverters and AC couple them. The Sunny Island tells them when to retard ouptut when the batteries are full by shifting the frequency slightly off nominal 50 or 60Hz. There are off the shelf BMS systems that can monitor the pack and communicate with the inverter so that it remains safe.

    What I'm waiting for is next generation off-grid hybrid inverters that use a 300-500VDC battery pack. The key accessory would be an interface kit that would bridge between the inverter and the BMS internal to the EV pack. It would also have to do things like tell the battery pack to close the contactor inside the pack so that the battery has a live connection to the inverter.
     
  12. Utahken

    Utahken Member

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    Yes they are gouging the customers... for instance, the powerwall 1.0 is $3000 from Tesla, then distributors add $800, then the installer adds their percentage, and shipping costs of $400-$600. Then the installers charge an arm an a leg to install it. It is so easy to install too! You can see it in the installation manual from Tesla. It is just Tesla insisting that things are done right to ensure a good customer experience. I would be just fine doing the install myself.
     
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  13. nativewolf

    nativewolf Member

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    #13 nativewolf, Nov 1, 2016
    Last edited: Nov 1, 2016

    You could look at Pika Energy's 380v islanding inverter. Probably just what you need because I'm looking for the same thing. In addition, another vendor was coming out with a 380v inverter, sma? solar edge? Can't remember. Anyway, Pika seems to have nailed the things I'd like. I'm just a year away unfortunately or fortunately as the case will turn out to be. Not many options but Pika is one of them. Oh, the only issue with them is that they can't use Sunpower panels (grounding issues).

    That said, if Tesla is bundling up lots of the power electronics into the pw2 than my life might have become a bit easier to manage, combined with the new roofs it's a very compelling option for new builds.
     
  14. Sodamo

    Sodamo Retired and busy :)

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    Outback has something in the pipeline called Skybox. Limited info on the OB site.
     
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  15. Sodamo

    Sodamo Retired and busy :)

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    Yes, I'm worried about the gouging, pretty rampant here in Hawaii. Many Mainland companies think we are ignorant on shipping and have turned it into another profit center.

    I suspect at very least the $1000 mentioned at the Tesla PW2 page will turn into $1000 per unit plus whatever the local guys try to add on.
    Seems on many things self install voids any warranty if you read the fine print. Often times I think long warranties are questionable. When I was expanding my PV a friend who was also looking to expand got really hung up on the warranty issue. My response was my already 7 yo panels (125w) were obsolete by technology and at 67 years old, perhaps anything 20 years or more was likely a lifetime warranty for me anyway.
     
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  16. techmaven

    techmaven Active Member

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    I just spoke to a rep at Tesla. He said that the PowerWall 2 can operate in off-grid fashion. Not much in terms of technical info available yet, but he indicated that you can connect solar strings directly to it. Outputs 240 volts, 120 volts, both, or no AC.
     
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  17. Sodamo

    Sodamo Retired and busy :)

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    Thanks, that's great news.
    Near as I can tell not many, if any PW1 configured for off grid. None that I can find on forums. I sometimes get the feeling that sometimes grid tied folks think loss of grid power equates to being off grid, not so from a configuration standpoint.
    Any hint when more info might become available?
    If I can drop PW2 between my PV and house distribution panel with just associated disconnects/breakers for a reasonable cost I'll happily sell my current system.
     
  18. techmaven

    techmaven Active Member

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    No additional info yet. They are building them in December for January delivery and he was saying that for now, they offer a free estimate for install which won't be free at some point.

    I asked about MPPT and he didn't know. The SolarEdge solution had MPPT built into their DC optimizers and not in the inverter. Gave them some of the benefits of microinverters. Not sure how it works in the PowerWall 2 setup.

    The SolarEdge SE-7600 with StorEdge seemed to require a grid connection for initial setup. I never checked with SolarEdge to find out if it could be set up offgrid only.
     
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  19. electracity

    electracity Active Member

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    I have the same impression. Off grid requires the capability to charge from AC (generator). I don't think solaredge has that implemented yet.

    I'll be surprised if Tesla has all the possible input/output capabilities within the Powerwall 2 box. But it would be neat if they did.
     
  20. miimura

    miimura Active Member

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    There was talk way back in 2013 of doing a standard for optimizers like what SolarEdge does. I didn't see any more articles about it in a recent Google search. That would be a good solution for solar input.
     
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