Wouldn't the most relevant measure, at least as far as emissions go, be the ratio of energy coming from renewables / solar vs. total energy consumption? Or something similar?
edit: spelling
US uses roughly 2.5-3x the energy per capita compared to china fwiw [1]. The energy use per capita can be influenced by all sorts of things, including climate - for instance, SGP will always be in the top few spots on this sort of list due to the space conditioning needs. Could also be due to lots of heavy industry. Could also be due to lots of inefficient homes or high consumer demand. So it can also be interesting to look at energy use per person plotted against GDP per capita, where as expected higher energy use per capita typically also means higher GDP per capita [2]. US has significantly higher GDP per capita.
Anyways, at the end of the day, in this kind of head-to-head energy technology race, the only thing I care about really at the end of the day is decarbonization. The US has been falling each year (not fast enough though, and much of it does not actually come from renewable adoption but instead other changes like natural gas replacing coal over the last decade and changes in mfg capacity etc) while China is still rapidly increasing. Both countries need to be doing more, way more (well really the whole world).
[1] https://ourworldindata.org/grapher/per-capita-energy-use
[2] https://ourworldindata.org/grapher/energy-use-per-person-vs-...