Where do I find the domestic content 10% tax credit adder for solar? Supposed to get 30% back + an extra 10% for US made materials (40% total)

"Solar power projects eligible for the full 30% tax credit can increase their tax credit by an additional 10% - to 40% in total - by purchasing domestically produced hardware. Per the document, 100% of steel and iron must be US manufactured in the United States. For manufactured goods - like solar panels, inverters, and electrical gear - the goods must initially be 40% US manufactured, though this percentage will increase in the future."

This is from the information I have and could also find in publications online, but I can't find where this takes effect in the deductions/credits, or instruction on how to claim this.

posted