The Delaware Renewable Energy Portfolio Standards Act (as amended, “REPSA”) requires retail electricity suppliers operating in the State of Delaware to purchase energy from “Eligible Energy Resources” to meet a portion of their retail load. For the 2011 compliance year (beginning June 1, 2011), retail electricity suppliers must purchase at least 7% of their retail load in Delaware from renewable resources. That requirement increases to 25% for the 2025 compliance year. The cost of procuring renewable energy to satisfy the requirements of REPSA is passed through to retail customers.
REPSA was amended in 2007 to require that a certain portion of each retail electricity supplier’s renewable energy requirement be satisfied with energy from solar technologies. The 2010 amendments to REPSA established a solar set aside of 0.20% for the 2011 compliance year, which increases to 3.50% for the 2025 compliance year. For 2026 and future compliance years, the Delaware Public Service Commission (“DPSC”) will establish solar set-asides at levels at least equal to the 2025 set-aside.
To encourage the development of new renewable energy generation, REPSA mandates that no more than 1% of the renewable energy purchase requirement can be satisfied by purchases from renewable energy generation resources (each, a “Generation Unit”) that were in commercial operation prior to January 1, 1998. For the 2026 and subsequent compliance years, no such pre-existing Generation Units will be eligible to satisfy any portion of the REPSA requirement.
When it enacted REPSA, the Delaware General Assembly acknowledged that “the benefits of electricity from renewable energy resources accrue to the public at large, and that electric suppliers and consumers share an obligation to develop a minimum level of these resources in the electricity supply portfolio of the state.” It therefore directed the DPSC to “establish, maintain or participate in a market-based renewable energy tracking system to facilitate the creation and transfer of renewable energy credits among retail electricity suppliers.”
 Eligible Energy Resources are defined to include those that produce solar photovoltaic or solar thermal energy, wind energy, ocean energy, geothermal energy or energy from fuel cells powered by renewable fuels. Also included are biogas, small-scale hydroelectric, biomass and certain qualifying landfill gas recovery projects. Eligible Energy Resources do not include waste-to-energy facilities, incinerators or generating resources fueled by fossil-fuel waste products.
 26 Del. Code Regs. § 351(b). The benefits recognized by the General Assembly include “improved regional and local air quality, improved public health, increased electric supply diversity, increased protection against price volatility and supply disruption, improved transmission and distribution performance, and new economic development opportunities.” Id.
 Id. § 359(a).