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Tesla's "solar roof" Event - Hosted at Universal Studios

Discussion in 'Tesla, Inc.' started by AssortedBread, Oct 24, 2016.

  1. Owner

    Owner Active Member

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    What I meant by that statement is that if you want to be off grid with just solar and batteries, you need to like double your solar and 5x batteries to make it through the winter.

    yes, a lot of people live off grid with generators and the like. Or those in developing countries with a lot less.
     
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  2. liuping

    liuping Active Member

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    #342 liuping, Nov 1, 2016
    Last edited: Nov 1, 2016
    Typically grid tied backup/solar systems do one of two things in that scenario:
    1) when batteries are full, a relay is used to cut power to the array (for micro inverters) or to the optimizer (for solar edge). Basically the panels shut down, just like they would if the grid was down and you did not have any batteries at all.
    2) a diversion load is used to burn off the excess power (usually something that looks like a large heating coil)
     
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  3. Garlan Garner

    Garlan Garner Banned

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    No, that makes no sense.

    There is only 1 inverter belonging to Solar Edge that is grid tied with the capability of being utilized with a battery. That's the SE7600 which is just now coming out to the market.

    When the batteries are full the SE7600 supplies all of its power to the GRID. Period. Its really simple. Why would a charged battery result in a disconnect of the Solar Panels? That makes no sense. The primary purpose of a grid tied inverter of any type is to provide excess power back to the grid to spin the customers meter backwards.
     
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  4. Garlan Garner

    Garlan Garner Banned

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    What? Why?
     
  5. ohmman

    ohmman Maximum Plaid Member

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    You and I are on the same page; but this is what I was implying.
     
  6. Lloyd

    Lloyd Well-Known Member

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    I have ~ 50 in my house for 12 years, and 30 in my office for 25 years and never had one act as you describe above!
     
  7. liuping

    liuping Active Member

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    That is only in the grid down / blackout scenario. I should have probably quoted more of the original post to make my reply more clear.

    By design grid tied PV systems must shut down when the grid goes down (to protect the linemen as they work the restore power, according to The SDG&E inspector we had). With a battery system, if you isolate your house from he grid fully during the blackout, the batteries can trick the panels/microinverter/dc optimizers into thinking everything is fine and they should produce power.
     
  8. Garlan Garner

    Garlan Garner Banned

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    Ok thanks. Yes the optimizers to shut down the panels to protect the lineman.

    Now the Powerwall 2 has its own inverter which allows for it to act independently from a SolarEdge system. When the grid goes down....either someone is going to have to manually disconnect the grid or there has to be some kind of automatic grid shut off installed. Then the Powerwall can do its thing without risk to the lineman. Interestingly - SolarEdge has indicated that Powerwall inverters are not aggressive enough to provide a robust enough AC signal to keep the SolarEdge inverters happy.

    Even more importantly - there has to be some kind of shutdown of the AC being delivered from the Powerwall before the grid comes back. If the Powerwall and the grid are connected together @ 180 degrees out of phase on the AC side - the Grid will probably spin the powerwall off the wall to force it back in phase.
     
  9. Theshadows

    Theshadows Active Member

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    This is all handled by the backup inverter. The inverter automatically disconnects for 5 mins when there is a grid disturbance. After the grid comes back up it has to wait 5 minutes to reconnect to the grid. While this delay is happening it is constantly monitoring the grid and getting back in sync with it so it will be phase matched when the reconnect happens.

    My theory on the PowerWall 2 is that it will have 2 sets of PV inputs, a grid in connection and a load out connection and ground. Possibly generator in. It will turn what currently takes us 10 man hours to do with an Outback Power system into 2 man hours. And if one inverter isn't enough the labor savings will be even more astounding.
     
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  10. Garlan Garner

    Garlan Garner Banned

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    Do you actually have a system? What backup inverter are you talking about?
     
  11. Theshadows

    Theshadows Active Member

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    Yes I have a system, 3 systems actually, and I have installed and designed over a dozen battery backup/ off grid systems. I just commissioned one today and will have the inspection tomorrow.

    We currently install Outback Power Radian systems AC coupled to Sunpower AC panels. I have been designing and installing residential and commercial solar energy systems for 7 years.
     
  12. Garlan Garner

    Garlan Garner Banned

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    Hmmmm ok. My Solar Edge system does not line up with what you are describing. See my system by clicking the link in my profile below.

    Do you have a link to one of your systems that you installed? A SolarEdge one?
     

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