What is your prediction for experimental solar cell efficiencies?
Unless you are dealing with space exploration, solar cell efficiencies are much less of a consideration than the installed cost per watt of solar cells. Recent advances in thin film technologies show promise in reducing solar cell costs per watt – even though they are likely to be less efficient than traditional silicon cell panels. Once the cost per watt of solar cells becomes competitive with other energy sources, they will be installed as a regular part of building construction. And the efficiency becomes even less important, because large quantities of them can be installed as part of integrated roofing systems, etc.
To me, this is a surprising development. I expected solar to eventually become cost effective by having efficiencies increase, and costs per square foot to stay the same. The possibility of having efficiencies decrease, but costs to decrease even more, is a very exciting, and unexpected, situation.