1970’s EPROMs can become small solar panels very easily.
The output from the Intel chip shown is around 0.4V and a few uA, usable for oscillator circuits if used in series.
Transistors will also work in a similar way, especially the large older ones if you cut the top off the metal can…the more silicon, the better output.
My Xevious arcade machine showed a ROM error recently and while inspecting the boardset I wondered about the EPROMs because they are silicon.
It turned out that a few people have shown vids on YouTube, but I haven’t found one where the EPROMs are shown running anything, just voltage outputs in strong sunlight.
The Xevious boardset now works fine and this video is to show what I found when testing other EPROMs.