Grid-tied solar inverter... faking the mains.

[Externet]

Good day.
A grid-tied solar inverter senses the electric utility presence, its voltage and frequency in order to work and inject energy back into the grid... I think.
It shuts-off when the utility mains has a problem or ceases working.

If entirely disconnected from the grid, a grid-tied inverter is fed by an oscillator faking the mains; would it be tricked to operate and supply power as an standalone off-grid inverter to a non-grid load ?
Or,
If a small 1:1 transformer powered by a working mains provides a voltage and frequency just to trick the inverter the mains is normally present; would the grid tied inverter work normally providing energy to a not-grid connected load ?

Does an off-grid inverter uses some internal oscillator to make 50 or 60Hz and regulate the (240VAC) outputted ?

 

[FvM]

Most grid-tied inverters, except for very simple designs, can be expected to include an internal oscillator that potentially allows autonomous operation (intentional islanding). Safety standards for grid-tied Inverters (IEEE 1547, UL 1741) require however recognition of unintentional islanding condition with automatic inverter shutdown. To support off-grid operation, the control mode must be changed to constant frequency/constant voltage and anti-islanding protection disabled. That's well possible for an inverter designer.

Dual use inverters (supporting grid-tied and off-grid operation) require a dedicated control interface and additional means to isolate the islanded power circuit from the grid.

 

[Easy peasy]

older and most grid tied inverters need to see a fairly low mains impedance to operate - if they try to export power and the AC volts go up ( your small transformer ) they will stop - further - they will often frequency pull to make sure the mains is there.

If it has a stand alone function - it can usually operate as a standard inverter up to a current limit set by the input power available ....

 

[Kripton2035]

take a look at hybrid inverters, they do what you want and they are not that much expensive.