In a world of extremely cheap solar electricity pushing grid prices negative, a lot of things might be a lot more economical then conventionally thought though - particularly when you factor in the desire to get a full return on industrial manufacturing of panels.
For me personally, this is one of the most promising aspects of solar that I hope to see in the future. There are many, many things we could do but currently do not because the energy cost is not worth it. Push the energy cost to zero, or even below, and it will be interesting to see what new things become abundant.