It wouldn't really need to generate "significant" power. At least, not in terms of whole-home power. Something like this could easily generate and store enough power for an auxiliary system, something like overnight lighting. Basically the same principle as those solar lawn lamps, but for inside. Wire 'em all to a battery and a bunch of lights and light/motion sensors throughout the home, and you've got automatic nightlights that work even when the power's out.

I figure the key would be finding a way to make these cost less (including upkeep/replacement over time) than the marginal energy generation capabilities.

On that note, I'm sure there's a reason besides "everyone else is too stupid to think of it" but I wonder why solar window shutters aren't a thing.