TITLE 26. INTERNAL REVENUE CODE § 25D. Residential clean energy credit., 26 USCS § 25D
(a) Allowance of credit. In the case of an individual, there shall be allowed as a credit against the tax imposed by this chapter [26 USCS §§ 1 et seq.] for the taxable year an amount equal to the sum of the applicable percentages of—
made by the taxpayer during such year.
(1) Maximum credit for fuel cells. In the case of any qualified fuel cell property expenditure, the credit allowed under subsection (a) (determined without regard to subsection (c)) for any taxable year shall not exceed $500 with respect to each half kilowatt of capacity of the qualified fuel cell property (as defined in section 48(c)(1) [26 USCS § 48(c)(1)]) to which such...