Prepare grill for direct cooking over high heat, 450°–550°. Brush cooking grates clean and close lid to heat.
Generously coat flesh side of salmon fillets with oil and season evenly with salt, pepper, paprika, and onion powder.
Grill salmon skin-side down over direct high heat with the lid closed for about 6–8 minutes or until the fish lightens in color and becomes more firm to the touch and you can lift fillets off cooking grates without them sticking.
Turn salmon over, close lid, and cook to 130° or about 2–4 minutes for medium-rare or longer to desired doneness. Transfer to a platter to rest for 1–2 minutes.
Slide salmon skin from fillets and serve with wedges of lemon.