I think you're misunderstanding to some degree. While silicon PV caps out at around 24% (I think up to 27% now), 100% conversion is basically impossible because of physics.

Plus, the sun basically has infinite energy, so it's not like efficiency is that big of a concern compared to energy density.

Solar isn't a solution for everything and that's precisely why China is pursuing a multi pronged approach for its transition off fossil fuels. China is actively developing wind power, geothermal, hydro, and nuclear on a massive scale. Each of these technologies has its own pros and cons, and they all work together.