Charles Ellicott Commentary 2 Chronicles 8:12

"Then Solomon offered burnt-offerings unto Jehovah on the altar of Jehovah, which he had built before the porch," — 2 Chronicles 8:12 (ASV)

(c) REGULATION OF THE TEMPLE WORSHIP
(2 Chronicles 8:12–16).

This whole section corresponds to the single verse, 1 Kings 9:25, which the chronicler has paraphrased in 2 Chronicles 8:12–13, and extended by the addition of further details in 2 Chronicles 8:14–15.

Then. —After the consecration of the Temple.

Offered. —Not once, but habitually; according to the prescriptions of the Mosaic Law (2 Chronicles 8:13).

On the altar ... which he had built. —And apparently no longer at Gibeon (2 Chronicles 1:3).

Before the porch. —Not in Kings.