The thing is, radiative processes (like light) can’t store energy. To do that, you need some kind of engine, either electrical or mechanical. Of course you cou

The thing is, radiative processes (like light) can’t store energy. To do that, you need some kind of engine, either electrical or mechanical. Of course you could put a solar panel connected to a battery in moonlight for a few months and build up enough stored energy to power a laser for long enough to fry something. But that’s not “burning something with moonlight using a magnifying glass.”