; and (ii) shall charge and collect from the eligible entity, as a credit subsidy fee, a payment equal to the amount determined under clause (i) to cover the cost of the proposed direct loan. (2) Terms and limitations (A) In general A direct loan issued under this Act shall be subject to such terms and conditions, and contain such covenants, representations, warranties, and requirements, including requirements for audits, as the Director determines appropriate. (B) Repayment No direct loan issued under this Act, including any part of the principal of, or interest on, such a direct loan, may be repaid with the proceeds of a sale to the Federal Government. (C) Interest rate The interest rate on a direct loan issued under this Act shall be not less than the average market yield on outstanding marketable United States Treasury securities having maturities comparable to the maturity of the direct loan on the date of execution of the loan agreement. (D) Maturity date The final maturity date of a direct loan issued under this Act shall be the earlier of— (i) the date that is 25 years after the date of substantial completion of the relevant project