; (C) to the maximum extent practicable, expand photovoltaic solar energy availability to— (i) geographical areas, throughout the United States and within States, territories, and Indian tribal land, with— (I) low photovoltaic solar penetration; or (II) areas with a higher cost burden with respect to the deployment or installation of photovoltaic solar electricity generating facilities; (ii) rural areas; (iii) Indian tribes; and (iv) other underserved areas, including Appalachian and Alaska Native communities; (D) take into account the warranty period and quality of the applicable photovoltaic solar electricity generating facility equipment and any necessary interconnecting equipment; and (E) ensure all calculations for estimated household energy savings are based solely on electricity offsets from the photovoltaic solar electricity generating facilities. (d) Loan and grant agreements (1) In general As a condition of receiving a loan or grant under this section, an eligible entity shall enter into a loan or grant agreement, as applicable, with the Secretary. (2) Requirements A loan or grant agreement under this subsection shall— (A) require the Secretary to rescind any amounts provided to the eligible entity that are not used during the 2-year period beginning on the date on which the amounts are initially distributed to the eligible entity, except in any case in which the eligible entity has demonstrated to the satisfaction of the Secretary that a longer period, not to exceed 3 years after the date of initial distribution, is necessary to deliver proposed services; (B) for a loan provided under this section, establish— (i) an interest rate equal to the then-current cost of funds to the Department of the Treasury for obligations of comparable maturity to the loan; and (ii) a payout time that maximizes the savings to subscribers during the effective period of the agreement