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New Experience

I've just received PTO from my utility, APS, and after charging my 2 Powerwalls to 100% I've been trying an experiment. I turned off the main circuit breaker in my breaker box and have been operating as an energy island for 3 days now, using only my solar panels and powerwalls to power my house. I don't have an electric vehicle. The only curiosity that I've noticed so far is that the digital clocks in my house (including the clock in my stove and my microwave oven) have been losing time ... about 5 minutes in a 24 hour period. Anyway, I was wondering if I need to do anything other that turn the main circuit breaker back on when I'm done with my experiment. Any Comments?

Comments

  • The Tesla Energy Gateway (TEG) uses a feature of Solar Photovoltaic (PV) inverters to control them. When in the off-grid mode, during the day, if the Powerwalls (PWs) are full, there's nowhere (besides the house) for the solar PV energy to go, so it's necessary to turn off the solar PV inverter if excess energy is produced.

    All solar PV inverters have an "anti-islanding" feature that kicks in when the grid goes down. This will shut off solar production if the inverter detects a "bad grid" condition. A bad grid is when either the grid voltage is out of spec (115V + or - a little), or the grid frequency is out of spec (60Hz + or - a little). What this does is prevents a solar PV power system from back-feeding the grid (creating an "island of power") when utility workers are trying to fix it. It can prevent injury or death of utility workers.

    In PW/PV installations, during the day, with full PWs, and excess production, the TEG will instruct the PWs to vary their output frequency to be just out of spec. (It's somewhere between 62.5 and 65Hz, IIRC.) Because the PV inverter sees the PW output as it's "grid", it will detect this out of nominal spec frequency as a bad grid, and shut off. With the PV inverter off, the house will take it's power from the PWs, until some space is left in them. The TEG will then instruct the PWs to go back to the 60Hz nominal frequency, which the PV inverter will see as a good grid, and turn itsself back on until the PWs are again full. The cycle continues as long as there's sunlight and the PV produces more than the house can use.

    Your clocks likely use the 60Hz grid frequency as their time base, which is very very accurate when the grid is powering the house. The frequency shifts of your PV/PW control system is probably driving them nuts. Many Uninterruptible Power Supplies (UPSs) are also adversely affected by these frequency shenanigans.

    It's a convoluted system, but it seems to work well.
  • About the cloaks. That is funny because I just finished watching a YouTube video were the person mentioned this exact thing. The PW run on 65 hertz so your clocks will run faster than the grid 50 hertz.

    Here’s the video. Be mentions it at 9:08 in the video.

    https://youtu.be/LFfxn2-iSGk
  • *clocks, not cloaks
    *60 hertz, not 50
  • Thanks for the comments. I flipped the circuit breaker in my main electrical panel back to "ON" so the grid is now available. It took about 5 minutes for the Tesla app to update. So my experiment ends after 5 days of our house being an "energy island". I'll continue to run as "Self-Powered" now for a couple of months and see what that does to me utility bill.
  • The five minute delay is your system's "decision delay time" (my terminology). The grid needs to be stable for up to five minutes or so before your PV/PW system decides it's OK to go back to normal grid-tied functioning. Inverters will do this even without PWs or a TEG.
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