Some of them are the foci of the interviews I conducted with him after his presentation (see the posts linked on the bottom of this article). But I decided to leave a couple of the points out of our interviews since they’re pretty straightforward and the chart presenting them is available on the NREL website, and now right here:

The takeaway points from the chart are:

1. The current efficiencies of all types of solar modules and solar cells are nowhere near their theoretical efficiency limits. (And that’s not to say the theoretical limits can’t also increase.)
2. Thin-film solar (CdTe) is especially ripe for efficiency improvements (commentary on that below), as are concentrated photovoltaics (CPV).

Thin-film solar panels were super hot until the price of conventional solar PV fell out the bottom and took nearly complete control of the market. Nonetheless, even today, First Solar (the leading thin-film solar company in the world) is the world’s #2 solar module manufacturer and #1 solar developer. Looking at the potential for efficiency improvements of this technology, thin-film solar’s future looks even brighter. (And, FYI, I talked with First Solar’s CTO the same day that I interviewed Dan Arvizu, and he hinted at the same thing, but couldn’t provide me with details on this matter at that time.)

The general benefit of thin-film solar is that it’s cheaper than conventional PV. Its downside is that it’s less efficient, but as you can see in the chart above, its theoretical efficiency limit is equal to or better than every other type of solar besides CPV (which is very efficient but still quite expensive).

Of course, there are thin-film solar companies other than First Solar that are vying to take a bigger portion of the market (such as Japan’s Solar Frontier), and they are trying to develop better thin-film solar technology in order to do so. And improvements to thin-film solar cell efficiency are being made regularly in labs and universities around the world. So, overall, it seems that we can expect that gap between real-world efficiency and theoretical efficiency to keep closing.

I guess the question this leaves us with is which technology or technologies will improve their real-world efficiencies using low-cost materials quickly enough to dominate the solar power market in the coming decades?

But one thing is clear: as solar becomes more efficient and cheaper, there’s no stopping its solar power growth across the world.