question

toolik avatar image
toolik asked

connecting 2 separate inverter/battery systems

I am upgrading my 25 year old 12v inverter battery solar system. The 18 year old 1670ah solar hup1 batteries are still in good working orderas is the Outback 2812 inverter . The replacement is a Quattro 48/5000/70 120v with 450ah of Lithionic batteries and upgraded solar. The electric system has expanded over the years so new building/loads are 400' away from the inverter . I plan to move the old system to the far end and continue using it to power the loads there There would be no connection between the 2 systems normally, my question is could I connect AC out from one inverter to AC in (grid) of the other to transfer excess from one to the other ?

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solardude avatar image
solardude answered ·

Yes, you can output from one inverters AC out to another inverters AC in. You would want separate battery banks obviously since DC runs that far away aren’t feasible.

One of my systems I have installed this way. I use it for redundancy on critical loads. The main panel is fed with 2X 48/5000’s 120/240V, 1200Ah lithium bank. The subpanel is a 48/3000, 300Ah lithium. If the main inverters ever fail, it would fall back to the 48/3000.

Solar charges the 1200Ah bank, which in turn charges the 300Ah bank through the 48/3000. If the 1200Ah bank were to ever shut down, a normally closed relay loses coil power, and the solar then charges the 300Ah bank directly.

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toolik avatar image toolik commented ·

Thanks Solardude, nice knowing I'm not alone with complicated schemes.

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Vance Mitchell avatar image
Vance Mitchell answered ·

If you use the AC out2 with an assistant set to turn it on when your batteries are full, it would automate the process for you and reduce the risk of flattening your new batteries if there’s a shortage of power.

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toolik avatar image toolik commented ·

That would work well for me in the warm months, but I also plan to use AC2 out in freezing weather to run the battery heaters pre charging. But that would be nice to have it automated in summer when there will be more excess solar.

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solardude avatar image solardude toolik commented ·

You could use the programmable relays as well to turn on/off an AC contactor with DC coil that controls the heating. Between the Quattros and/or a Venus device, you can pretty well automate anything you need.

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