I want to run a microcontroller circuit at about 3V 10mA on the high side of a several kilovolt supply. I know there are various solutions, but I'd like to use a 'solar cell' to supply isolated power.
It's too much power for normal photovoltaic isolators by some orders of magnitude, so I'm considering using one or more photovoltaic cells with one or more LEDs shining on them. It's all in an enclosure, so there's no significant ambient light. The cell(s) could be several square centimeters area. I like this arrangement as the isolation isn't in any doubt - there could be centimetres of gap.
What sort of size cells would I need for around 30mW? I guess blue LEDs would be best? An efficiency of 1% (a 3W input) would be fine, even a bit less. Just musing at the moment and if anyone has any ball-park feelings or experience that would be good.
Cheers