When I first stumbled on to them I thought they must be a gift from God himself.
Then I realized the extremely limited Current available, and it popped my bubble.
On the other hand, a FET Gate only requires an RMS Current of around ~10%, or maybe even less,
of its PEAK Current Requirements during the actual switching transition time.
So, Capacitors are your friend ......... Maybe even an Inductor-Input Power-Supply topology.
Do the actual switching with a Darlington-Output-Opto,
and use the PV-Cells for a DC "Power-Supply".
Check out this Idea .......
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.View attachment 230533
Note: Resized to be more friendly toward small screens.
I was thinking of something similar, but using a standard halfbridge driver and replacing the boot cap diode part of the circuit with one of the photo chips. The driver would do the orginal fet turn on (for speed) and the photo chip would take the place of the boot circuit.