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Two mains supplies - 1) for EV via relay, 2) to power openEVSE

Is there any technical or safety reason I can’t feed two mains supplies to my openEVSE? One supply would just be connected to the main relay and the second supply would be connected to the AC input of the controller board. The reason I want to do this is that I’m going to be switching the power feed between the grid and an off-grid PV system and I want the openEVSE to stay powered on from the grid mains. The only potential issue I can see relates to the AC Test connections. When my car is being charged from the PV it could be at a slightly different voltage (both will be approximately 240v) and will almost certainly be out of phase. Has anyone tried this?

To be clear, the power feed that can be switched between the grid and the PV system is the power that will charge the EV when the relay closes.  The separate mains power feed that will power the electronics and control circuitry inside the openEVSE itself will always be fed from the grid.

I do not believe it has ever been tried. The AC_Test should work okay if everything has a common ground. The test is just power through an LED and detector.

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