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alphalinux avatar image
alphalinux asked

Semi Off-Grid System; recommendations ?

Hi all

I'm fairly new to Victron products and need some advice for building a system to power my Home-Lab.

Goal:
Home-Lab should be powered by PV energy as long as there's enough power from pv panels and/or battery storage. As soon as there's no energy left to power my Lab it should automatically switch to Grid power. When there's again energy from pv/battery an automatic transfer to PV energy should occur.
This system shall NOT feed energy to the grid.

Already found a Automatic Transfer Switch with capability of Monitoring battery voltage; as soon as battery voltage drops a certain value it transfer to grid power and back to to PV when battery voltage above threshold. Unfortunately, this ATS is just a mechanical switch by relays. So, no phase sync to 50Hz grid does happen, which is quite dangerous for some reasons.

I very much appreciate any recommendations regarding product selection and design of such a system.


best regards,

pv-battery-ats-layout.jpg


MultiPlus Quattro Inverter ChargeroffgridAutotransformer
pv-battery-ats-layout.jpg (33.7 KiB)
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2 Answers
Mike Dorsett avatar image
Mike Dorsett answered ·

A multiplus inverter wiht battery already includes the transfer switch with phase sync - this can perform UPS function and will eliminate the need for an external transfer switch. Best to download a multi or quatro manual and look at the example schematics at the back of the manual.

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Bruce Fergusson avatar image
Bruce Fergusson answered ·

FWIW - Food for thought - If I understand correctly, you want to prioritize inverter output over grid,which I believe will require an transfer external switch as you described. The inverter internal switch can have the unit behave as UPS, prioritizing grid. If you connect the inverter input to the grid, it will sync to grid while “behind” the external switch in the arrangement you describe, minimizing the chance of an “unsync’d“ transfer.


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