I believe it's on the order of magnitude of 100x return (for a low-orbit space photovoltiac panel that's (almost) always facing direct sun).
(/ (* ([W (kg -1)] 200) ;; reasonable space PV power/mass ratio
([year] 10) ;; guess at lifespan
([ton] 100)) ;; Starship payload
(* ([ton] 1000) ;; tons of liquid methane in Starsihp
([J (kg -1)] 5e7))) ;; specific energy density of CHâ‚„
;; => 126.226944