John Gill Commentary 2 Chronicles 11:15

"and he appointed him priests for the high places, and for the he-goats, and for the calves which he had made." — 2 Chronicles 11:15 (ASV)

And he ordained him priests for the high places
Of such who were not of the tribe of Levi, and family of Aaron; see (1 Kings 12:31)

and for the devils ;
demons in the shape of goats, as this word signifies, in which form many of the Heathen deities were worshipped; idols of whatsoever kind are so called; for whosoever worships them worships not God, but devils, (1 Corinthians 10:21) the images which Jeroboam set up may be meant, and the next clause may be rendered as explanative of them:

even for the calves which he had made ;
one of which he set up at Dan, and the other at Bethel, (1 Kings 12:28 1 Kings 12:29) .