NREL Module Efficiency - Then and Now

In April 2009 I began my career in the solar industry with Eos Energy Solutions, a small PV installation “start-up” out of the owner’s house near Center City Philadelphia. I no longer work directly in solar, but it’s still a passion of mine. During this time I recall looking at NREL’s “Best Research-Cell Efficiencies” graph trying to decipher the different technology and compare it to what we were installing. Below is the 2005 graph - I had this printed and pinned to the wall near my desk.

Image courtesy of NREL.

It’s now 2020, more than ten years later, and I was wondering what that graph looks like now…

Image courtesy of NREL.

We mostly installed mono and multi-crystalline with some thin film mixed in. In 2005, mono and multi efficiencies peaked at around 24% and 19% respectively. In the 2020 graph, mono and multi efficiencies were about 26% and 23% respectively. Modest gains for sure in the crystalline silicon sub-sector, but really impressive gains in the multijunction sub-sector with peaks in the high 30s for non-concentrators. It’s also great to see so many more technologies being tested and pursued. If you’re curious what some of these technologies are, NREL has good summary on the topic. Or if you are interested in what other PV research NREL is working on, follow this link. For the crystalline silicon market, and for those customers looking at installing PV on their house or business, does the efficiency plateau mean most commercially available modules are closer to the upper-bound efficiency now? (In 2009-2014 I recall most efficiencies in the 14-16% range.) Or because we’re pushing the theoretical efficiency limit, and there is no cost-benefit to improve manufacturing process to realize the small cell gains, price stratification has remained the same? In another post I’ll do some $/watt comparisons to see how the market has changed.