A substantial part of the global sugarcane crop is used to make ethanol for fuel. The world's biggest producer, Brazil, uses the majority of its crop for ethanol. (65% as of 2019, the most recent number I could find [0]).

Wikipedia's "Sugarcane" article quotes a 2005 source to claim "solar energy-to-ethanol conversion efficiency is 0.13%". It might be slightly better now, but it's not going to match the 20% or more of a modern photovoltaic system, which could be used to power electric vehicles instead (an ideal use of solar energy, because electric vehicles need batteries anyway so there's no base load problem).

[0] https://www.reuters.com/article/cofco-sugar-ethanol/cofco-ex...