It’s a little misleadingly worded. Looking at the original press release[1] and an earlier announcement[2] I think they mean that they have prototype versions of this panel with 29.5% efficiency, the first production version they’re talking about here isn’t at that level yet.

[1]https://www.oxfordpv.com/news/20-more-powerful-tandem-solar-... [2]https://www.oxfordpv.com/news/oxford-pv-hits-new-world-recor...