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SunMax Solar + AC Powerwalls

Discussion in 'Tesla Energy' started by doubleohwhat, Apr 1, 2017.

  1. doubleohwhat

    doubleohwhat Supporting Member

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    I've been offered a solar system that a friend purchased last fall but was never able to install due to his HOA (I have no clue why he didn't get permission from the HOA before purchasing). It's a 5.2K system and I've been offered the whole lot, new in the boxes for $5K.

    On the surface it seems like a pretty good deal. However, it's a SunMax system from Ubiquiti which is a unique system. It converts the DC to AC at each panel using micro-inverters. I've attached a screenshot of how I'd possible install the system at my location which shows the output etc.

    The problem is with the "at the panel" DC-AC conversion. With a traditional system where the conversion happens at the single inverter, I could just switch my planned 3 AC Powerwalls over to DC Powerwalls.

    So my questions is: Would I be able to store the excess energy from this solar system in my AC powerwalls? How would that work? Perhaps charge them 2/3 overnight and let the solar fill up what it can the following day before the peak period?

    I'm not so much concerned about cost as I am how it would physically work. Thoughts?
     

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  2. montreid

    montreid Member

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    You'll have to talk with them on this. I don't know if Powerwalls work on AC since the scematics i've seen is that powerwall feeds into an inverter that does the DC>AC conversion (from either solar panels or powerwall).

    Weird about the HOA thing. HOA legally cannot forbid solar array installations in Cali IIRC.
     
  3. doubleohwhat

    doubleohwhat Supporting Member

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    HOAs have way too much power here. The only reason my HOA doesn't care is because the panels would not be visible from the street.
     
  4. Saghost

    Saghost Active Member

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    I'm sure there will be a solution - your situation is the same as any of the thousands of folks who have microinverters. You obviously need the AC version of the powerwall, which we haven't really seen yet.

    My expectation is that the AC powerwall will have a connection module with integrated transfer switch, which sits between the grid and the protected portion of your house circuits (which would include the Solar.)

    With this connection module, it can read how much power is coming and going - and isolate you from the grid during a failure. To charge the pack from solar, it would draw power from the protected side until the current flow from the grid zeros and keep it that way until you either run out of sun or fill the pack up.

    To do any sort of load shaving or arbitrage or to optimize usage in a time of use environment you'll need some smart controls for what the pack is doing, which I'm assuming Tesla will provide in the form of a web page (but again, something I haven't seen, and haven't seen descriptions of.)
     
  5. Ampster

    Ampster Member

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    That fits within the definition of AC coupled. Essentially that is how mine works with Mini inverters. If you in tall it behind the meter and dont feed the grid you should not have to ask permission from your utility. A building pemit for a battery backup is all you should need.
     
  6. miimura

    miimura Active Member

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    I don't know how you would install a PowerWall and micro-inverter based solar so that it can't feed back into the grid except for islanding during a grid outage. An Outback Radian has separate AC connections for the "battery charger" input and the inverter output. With that configuration, you can actually isolate the battery so it can't feed back into the grid, yet it can take energy from the grid as needed.
     
  7. Ampster

    Ampster Member

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    I should have been more clear. I only meant the battery and the inverter integrated in that. At least with my Radian I can configure it to never sell to the grid. That is what I meant by "behind the meter". I also meant to say install but by the time I saw my mistake I couldn't edit.
     
  8. doubleohwhat

    doubleohwhat Supporting Member

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    After looking into this further I think the best solution for me is to go with a solaredge storedge inverter, proper panels and solaredge optimizers.

    Though Before proceeding, I need to make sure:

    A) that storedge inverter is compatible with Powerwall 2 *and* I can install at least two powerwall 2 units

    B) that the DC version of the powerwall 2 will still be available by the time they get to my installation.

    I have an email in to solaredge for A but getting an answer to B might be an issue.
     
  9. miimura

    miimura Active Member

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    Regardless of the PowerWall configuration, you probably have to get permission for battery grid interconnection, just like you have to get permission for solar interconnection. The only way you won't have to do that is to engineer/configure the system so that it cannot back-feed into the grid, like you can with a Radian.
     
  10. doubleohwhat

    doubleohwhat Supporting Member

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    I actually prefer the Radian but I'm not sure what I would do for battery storage with that inverter. I need at least 20kWh usable. Two 13kWh powerwalls work well for that need because with. 30% degredation over ten years, I'll still have close to 20kWh usable.
     
  11. Deans

    Deans Member

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    What state does your friend live in? Many states have laws that invalidate HOA restrictions on solar panels.
     
  12. doubleohwhat

    doubleohwhat Supporting Member

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    It's Alabama. No such laws here to my knowledge.
     
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  13. Deans

    Deans Member

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    Correct. Alabama is one of the ten states that does not have any such laws. Bummer.
     
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  14. doubleohwhat

    doubleohwhat Supporting Member

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    Alabama doesn't even know solar energy is a thing. Explaining how a EV works is challenging enough. I was at a L2 charger late last year, a lady saw the cable plugged into the car and asked what kind of fuel it took. I tried explaining it to her but she kept insisting that I was putting some kind flowing liquid into the car. I finally gave up and just said "It's premium electron juice." She said "I knew it had to be something coming out of the pump" and walked off. I truly wish I was joking (and that someone had recorded that conversation).

    Do you happen to have a link to some place I can read up on using salvaged batteries with a Radian?
     
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  15. miimura

    miimura Active Member

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  16. jffkm

    jffkm New Member

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    Just wanted to follow up on this as I am thinking about installing a similar system. Put in a request for a powerwall 2 system and planning on installing a low-cost solar system with microinverters, probably the same one (sunmax ubiquiti). Any thoughts or feedback on whether this is possible with the current powerwall offering? I searched ubiquiti forums but did not find any info on this post powerwall 2 introduction. Most of the content had to do with the older DC powerwall which was not compatible.
     
  17. Kacey Green

    Kacey Green Member

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    When I chatted with Tesla Energy they told me my Enphase microinverter system would work
     

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