476C.2  Tax credit amount — limitations.
  1.  A producer or purchaser of renewable energy may receive renewable energy tax credits under this chapter in an amount equal to one and one-half cents per kilowatt-hour of electricity, or four dollars and fifty cents per million British thermal units of heat for a commercial purpose, or four dollars and fifty cents per million British thermal units of methane gas or other biogas used to generate electricity, or one dollar and forty-four cents per one thousand standard cubic feet of hydrogen fuel generated by and purchased from an eligible renewable energy facility or used for on-site consumption by the producer.
  2.  The renewable energy tax credit shall not be allowed for any kilowatt-hour of electricity, British thermal unit of heat for a commercial purpose, British thermal unit of methane gas or other biogas used to generate electricity, or standard cubic foot of hydrogen fuel that is purchased from an eligible renewable energy facility by a related person. For purposes of this subsection, persons shall be treated as related to each other if either person owns an eighty percent or more equity interest in the other person.
  3.  A taxpayer who is eligible to claim a renewable energy tax credit under this chapter shall not be eligible to claim a solar energy system tax credit under section 422.11L or 422.33.
2005 Acts, ch 160, §8, 14; 2011 Acts, ch 115, §6; 2012 Acts, ch 1121, §9 – 11
Subsection 3 takes effect May 25, 2012, and applies retroactively to tax years beginning on or after January 1, 2012; 
2012 Acts, ch 1121, §10, 11