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  • We bought a couple of SMA Sunny Island off-grid inverters! Wohooo! I ended up getting my hands on a couple of Chevy Volt batteries and a 3ft x 4ft Hoffman steel box.

    The Sunny Island inverters are capable of tricking my Grid-Tied inverter into thinking the grid is still active and getting them to make power when the grid goes down.

    So now, when we lose power, (3 to 5 times a year) instead of having to listen to a generator screaming all day, I just flip a couple of breakers, push a couple buttons, and the power comes back on like magic! The Sunny Island inverters draw power from the Chevy Volt Lithium Ion battery bank and energize the house with grid-quality power. After a few minutes, when the inverter on the solar array see's the power, it thinks the grid is back up again and it starts pumping juice into the home. If the solar array is making more power than the home is using, the Sunny Island will use the extra power to charge the batteries, and if the batteries are already charged, it can heat water or throttle back the solar array output.

    This thing works great. I can literally disconnect from the grid and run the home indefinitely like nothing was wrong. Well, at least up to the point where the batteries have been cycled to the end of their life span.

    If we get a long string of dark cloudy days or heavy snow and the solar can't keep up, we can then fire up the generator and feed it into the Sunny Island inverters. They will then power the home on generator power and charge the batteries.

    Best addition I have added so far!

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    • Very cool Murphy. What physical size and electrical size are those Volt batteries? Were they a junkyard find? any chance you'd share a pic or 2 of the entire set up?
      I can explain it to you, but I can't understand it for you!

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      • Originally posted by CountryGuy View Post
        Very cool Murphy. What physical size and electrical size are those Volt batteries? Were they a junkyard find? any chance you'd share a pic or 2 of the entire set up?
        The Chevy Volt battery comes as a T shaped assembly that is about 5 feet long and 36 inches wide @ around 400 lbs or so and with a voltage just shy of 400 volts DC max (360 nominal). When you disassemble it, it breaks down into individual modules. There are 9 modules inside, 7 of them are 48 volts, two are at 24 volts. So you combine the two 24v modules and you end up with 8 modules at 48 volts DC. These are bundled together (two in each bundle) but can be split apart into the 12cell @48v. Each weighs 48vdc unit about 45 lbs so its 8 x 45lbs total weight.
        Each bundle of two 48vdc modules is about 9 inches wide, 9 inches tall, and 19 inches long. I found mine on Craigslist.

        My unit is sitting behind a pile of prepper supplies and other crap as we are re-arraigning the basement. My stuff has been spread out over a dozen different kinds of shelving units. From those plastic home depot things to some home-built shelves, it looks kind of disorganized. I got my hands on a bunch of heavy duty retail Gondola Shelving and am transferring everything over so the basement looks like a bomb hit it right now.

        If you google Chevy Volt battery, there's a lot of information on them as well as a lot of youtube video's of people using them for off-grid solar storage. Most are messy do-it-yourself builds and not very professional, but they provide a good idea of how it works.

        The real magic comes from the Sunny Island system. Beyond my own solar system, I could actually cause other grid-tied inverters in the neighborhood to kick in and produce power in an SHTF collapse type of event. I know of two other solar homes within a 1/2 mile of me.

        Check out the video:
        https://www.youtube.com/watch?v=rA0msd2ZQWI

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        • Thank Murphy. So in your opinion how do the Volt batteries compare to the deep cycle forklift and marine batteries people use in higher end battery banks, equal or better?
          I can explain it to you, but I can't understand it for you!

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