The Commission shall implement a renewable energy portfolio standard that, except as provided under paragraphs (2) and (3) of this subsection, applies to all retail electricity sales in the State by electricity suppliers. If the standard becomes applicable to electricity sold to a customer after the start of a calendar year, the standard does not apply to electricity sold to the customer during that portion of the year before the standard became applicable. A renewable energy portfolio standard may not apply to electricity sales at retail by any electricity supplier: in excess of 300,000,000 kilowatt–hours of industrial process load to a single customer in a year; to residential customers in a region of the State in which electricity prices for residential customers are subject to a freeze or cap contained in a settlement agreement entered into under § 7–505 of this title until the freeze or cap has expired; or to a customer served by an electric cooperative under an electricity supplier purchase agreement that existed on October 1, 2004, until the expiration of the agreement, as the agreement may be renewed or amended. The portion of a renewable energy portfolio standard that represents offshore wind energy: applies only to the distribution sales of electric companies; and may not apply to distribution sales by any electric company in excess of: 75,000,000 kilowatt–hours of industrial process load to a single customer in a year; and 3,000 kilowatt–hours of electricity in a month to a customer who is an owner of agricultural land and files an Internal Revenue Service form 1040, schedule F. Except as provided in subsections (e) and (f) of this section, the renewable energy portfolio standard shall be as follows: in 2006, 1% from Tier 1 renewable sources and 2.5% from Tier 2 renewable sources; in 2007, 1% from Tier 1 renewable sources and 2.5% from Tier 2 renewable sources; in 2008, 2.005% from Tier 1 renewable sources, including at least 0.005% derived from solar energy, and 2.5% from Tier 2 renewable sources; in 2009, 2.01% from Tier 1 renewable sources, including at least 0.01% derived from solar energy, and 2.5% from Tier 2 renewable sources; in 2010, 3.025% from Tier 1 renewable sources, including at least 0.025% derived from solar energy, and 2.5% from Tier 2 renewable sources; in 2011, 5.0% from Tier 1 renewable sources, including at least 0.05% derived from solar energy, and 2.5% from Tier 2 renewable sources; in 2012, 6.5% from Tier 1 renewable sources, including at least 0.1% derived from solar energy, and 2.5% from Tier 2 renewable sources; in 2013, 8.2% from Tier 1 renewable sources, including at least 0.25% derived from solar energy, and 2.5% from Tier 2 renewable sources; in 2014, 10.3% from Tier 1 renewable sources, including at least 0.35% derived from solar energy, and 2.5% from Tier 2 renewable sources; in 2015, 10.5% from Tier 1 renewable sources, including at least 0.5% derived from solar energy, and 2.5% from Tier 2 renewable sources; in 2016, 12.7% from Tier 1 renewable sources, including at least 0.7% derived from solar energy, and 2.5% from Tier 2 renewable sources; in 2017: 1% from Tier 1 renewable sources, including: at least 1.15% derived from solar energy; and an amount set by the Commission under § 7–704.2(a) of this subtitle, not to exceed 2.5%, derived from offshore wind energy; and 5% from Tier 2 renewable sources; in 2018: 8% from Tier 1 renewable sources, including: at least 1.5% derived from solar energy; and an amount set by the Commission under § 7–704.2(a) of this subtitle, not to exceed 2.5%, derived from offshore wind energy; and 5% from Tier 2 renewable sources; in 2019: 7% from Tier 1 renewable sources, including: at least 5.5% derived from solar energy; and an amount set by the Commission under § 7–704.2(a) of this subtitle, not to exceed 2.5%, derived from offshore wind energy; and 5% from Tier 2 renewable sources; in 2020: 28% from Tier 1 renewable sources, including: at least 6% derived from solar energy; and an amount set by the Commission under § 7–704.2(a) of this subtitle, not to exceed 2.5%, derived from offshore wind energy; and 5% from Tier 2 renewable sources; in 2021: 8% from Tier 1 renewable sources, including: at least 7.5% derived from solar energy; and an amount set by the Commission under § 7–704.2(a) of this subtitle derived from offshore wind energy; and 5% from Tier 2 renewable sources; in 2022: 1% from Tier 1 renewable sources, including: at least 5.5% derived from solar energy; and an amount set by the Commission under § 7–704.2(a) of this subtitle derived from offshore wind energy; and 5% from Tier 2 renewable sources; in 2023: 9% from Tier 1 renewable sources, including: at least 6% derived from solar energy; an amount set by the Commission under § 7–704.2(a) of this subtitle derived from offshore wind energy; and at least 0.05% derived from post–2022 geothermal systems; and 5% from Tier 2 renewable sources; in 2024: 7% from Tier 1 renewable sources, including: at least 6.5% derived from solar energy; an amount set by the Commission under § 7–704.2(a) of this subtitle derived from offshore wind energy; and at least 0.15% derived from post–2022 geothermal systems; and 5% from Tier 2 renewable sources; in 2025: 5% from Tier 1 renewable sources, including: at least 7% derived from solar energy; an amount set by the Commission under § 7–704.2(a) of this subtitle, not to exceed 10%, derived from offshore wind energy; and at least 0.25% derived from post–2022 geothermal systems; and 5% from Tier 2 renewable sources; in 2026: 38% from Tier 1 renewable sources, including: at least 8% derived from solar energy; an amount set by the Commission under § 7–704.2(a) of this subtitle derived from offshore wind energy, including at least 400 megawatts of Round 2 offshore wind projects; and at least 0.5% derived from post–2022 geothermal systems; and 5% from Tier 2 renewable sources; in 2027: 5% from Tier 1 renewable sources, including: at least 9.5% derived from solar energy; an amount set by the Commission under § 7–704.2(a) of this subtitle derived from offshore wind energy, including at least 400 megawatts of Round 2 offshore wind projects; and at least 0.75% derived from post–2022 geothermal systems; and 5% from Tier 2 renewable sources; in 2028: 43% from Tier 1 renewable sources, including: at least 11% derived from solar energy; an amount set by the Commission under § 7–704.2(a) of this subtitle derived from offshore wind energy, including at least 800 megawatts of Round 2 offshore wind projects; and at least 1% derived from post–2022 geothermal systems; and 5% from Tier 2 renewable sources; in 2029: 5% from Tier 1 renewable sources, including: at least 12.5% derived from solar energy; an amount set by the Commission under § 7–704.2(a) of this subtitle derived from offshore wind energy, including at least 800 megawatts of Round 2 offshore wind projects; and at least 1% derived from post–2022 geothermal systems; and 5% from Tier 2 renewable sources; and in 2030 and later: 50% from Tier 1 renewable sources, including: at least 14.5% derived from solar energy; an amount set by the Commission under § 7–704.2(a) of this subtitle derived from offshore wind energy, including at least 1,200 megawatts of Round 2 offshore wind projects; and at least 1% derived from post–2022 geothermal systems; and 5% from Tier 2 renewable sources. Before calculating the number of credits required to meet the percentages established under subsection (b) of this section, an electricity supplier shall exclude from its total retail electricity sales all retail electricity sales described in subsection (a)(2) and (3) of this section. Subject to subsections (a) and (c) of this section, an electricity supplier shall meet the renewable energy portfolio standard for all Tier 1 and Tier 2 renewable sources except offshore wind by accumulating the equivalent amount of renewable energy credits that equal the percentages required under this section. An electric company shall meet the renewable energy portfolio standard for offshore wind in accordance with § 7–704.2 of this subtitle. The required percentage of an electric cooperative’s renewable energy portfolio standard derived from solar energy shall be 2.5% in 2020 and later. The required percentage of a municipal electric utility’s renewable energy portfolio standard shall be: in 2021: 4% from Tier 1 renewable sources, including: at least 1.95% derived from solar energy; and an amount set by the Commission under § 7–704.2(a) of this subtitle, not to exceed 2.5%, derived from offshore wind energy; and 5% from Tier 2 renewable sources; and in 2022 and later, 20.4% from Tier 1 renewable sources, including: at least 1.95% derived from solar energy; and an amount set by the Commission under § 7–704.2(a) of this subtitle, not to exceed 2.5%, derived from offshore wind energy. In this subsection the following words have the meanings indicated. “Area median income” has the meaning stated in § 4–1801 of the Housing and Community Development Article. “Low or moderate income housing” means housing that is affordable for a household with an aggregate annual income that is below 120% of the area median income. At least 25% of the required percentage of the renewable energy portfolio for each year as set forth in subsection (b) of this section derived from post–2022 geothermal systems shall be derived from systems that were installed: at single or multifamily housing units that qualified as low or moderate income housing on the date the system was installed on the property; or at institutions that primarily serve low and moderate income individuals and families, including: schools with a majority of students who are eligible for free and reduced price meals; hospitals with a majority of patients eligible for financial assistance or who are enrolled in Medicaid; and other institutions that serve individuals and families where the majority of those served are eligible based on income for federal or State safety net programs.