It's not just about costs. It's about size! The higher the efficiency, the less solar cells you need. This has impacts on environment (solar cell farms), adds

It's not just about costs. It's about size! The higher the efficiency, the less solar cells you need. This has impacts on environment (solar cell farms), adds possibilities for miniaturization (what, if a vehicles rooftop could feed all the energy needs of said vehicle or, at least, constantly refuel it?), mobile device chargers (could be even become the outer hull of a battery, so you just need to place the battery in light to charge it), small cells, that produce high energy, could be made part of clothing (must not be this tech, I am thinking about miniaturization in general). Possibilities seem endless...