"What I don't get is why private industry doesn't see this as an opportunity for economic growth."

There are thousands of companies trying. The inherent problem is that solar and wind are generally crap ways to make it work.

If you live near the equator, and don't regularly have access to electricity, and need a panel to power your TV for a few hours a day - then that's 'impact' but in the West it's really, really hard to make work.