Select RPS publications are listed below. Use the following links to jump to a section: 

  Selected Reports and Papers from the RPS Collaborative

Case Studies of RPS Best Practices: Solar Carve-Outs, SREC Tracking, and Thermal Inclusion, by Jenny Heeter, Edward Holt, Sam Koebrich, and Val Stori, July 2018. The paper consists of three case studies of states that have been leaders in implementing particular RPS practices: Delaware’s use of a carve-out for solar, New Jersey’s tracking of solar renewable energy certificates (SRECs), and New Hampshire’s inclusion of thermal output in its RPS.  

Credit Multipliers in Renewable Portfolio Standards
, by Brian Lips, July 2018. This report examines the history and status of credit multipliers, the types of technologies and applications most often awarded credit multipliers, the advantages and disadvantages of credit multipliers, state experiences with the use of multipliers, and other trends in the implementation of credit multipliers.

When Renewable Portfolio Standards Max Out, by Ed Holt, June 2017. Many state RPS policies will reach their peak requirement over the next few years. This report explores the implications not just for the state reaching its peak requirement but also for nearby states. It also presents the options a state has for acting (or not acting) at that time.

Does Energy Storage Fit in an RPS? By Ed Holt and Todd Olinsky-Paul, July 2016. This is an updated version of a report originally published in 2014. This paper explores the question of how states, which have taken the lead in promoting clean energy through RPS programs, could facilitate increased deployment of energy storage.

Designing the Right RPS: A Guide to Selecting Goals and Program Options for a Renewable Portfolio Standard, by Warren Leon, March 2012. Although this report is especially useful to states considering establishing a new RPS, it is also helpful to states that are considering RPS program modifications. It describes RPS best practices and analyzes a wide range of options in RPS program design.

Distributed Generation in State Renewable Portfolio Standards, by Samantha Donalds, July 2017. In 2016-2017, CESA conducted a survey on how distributed generation is incorporated into state RPSs. CESA collected responses from all 30 states that currently have a mandatory RPS requirement. This report provides a summary of the results from that survey.

Two Markets, Overlapping Goals: Exploring the Intersection of RPS and Voluntary Markets for Renewable Energy in the U.S., by Todd Jones, July 2017.  This paper explores interactions between RPS and voluntary markets for renewable energy in the U.S. and outlines principles for supporting continued growth of both markets.

Potential RPS Markets for Renewable Energy Generators, by Ed Holt, July 2016. This paper provides information regarding where a renewable energy generator in a particular state or Canadian province can potentially sell its renewable energy certificates in order to meet the demand created by an RPS. The data in the report is also available as an interactive map. The paper and map were originally published in 2014, and were updated in 2016 to reflect RPS changes in various states. 

RPS Compliance Data Collection and Reporting Practices: Supporting Renewable Energy Policy Implementation through Information Sharing, prepared for CESA's RPS Collaborative by Sustainable Energy Advantage, LLC. The topic of RPS data management is often overlooked. To enable a closer examination of this important topic, the Clean Energy States Alliance (CESA) conducted a survey of RPS program administrators to gain insight into the collection, use, and reporting of RPS compliance data. Based on the responses, the consulting firm Sustainable Energy Advantage (SEA) then wrote a report summarizing the various states’ collection and reporting practices. The report also identifies some best practices and includes SEA’s recommendations for effective use of RPS compliance data and reports. Information is included on all states with established RPSs. June 2015.

Renewable Thermal in State Renewable Portfolio Standards, by Samantha Donalds, July 2018. This report provides an overview of how states across the country are incorporating renewable thermal technologies into their RPS programs.

Environmental Rules for Hydropower in State Renewable Portfolio Standards, by Val Stori, April 2013. This paper looks at various approaches states have taken in their RPS policies to safeguard the environment when hydropower is developed. It describes the rules for hydropower qualification, especially those having to do with environmental standards. 

Evaluating the Benefits and Costs of a Renewable Portfolio Standards: A Guide for State RPS Programs, by Warren Leon, May 2012. This report explains some of the issues associated with RPS evaluation and presents four options for how states may choose to proceed. The report begins with an explanation of why RPS costs and benefits are so difficult to quantify, and then goes on to explain the advantages and disadvantages of each approach. 

REC Definitions and Tracking Mechanisms Used by State RPS Programs, by Jan Hamrin, June 2014. To facilitate REC trading between regions and to help state renewable energy program administrators understand how their state compares to others, this report provides information on the use of RECs by states, on the definitions of a REC, and on the environmental attributes included in a REC. The report also discusses how different regional and state-based REC tracking systems handle these matters.

The State of State Renewable Portfolio Standards, by Warren Leon, June 2013. This report analyzes state renewable portfolio standard laws as a policy mechanism, identifying their strengths and weaknesses, and assessing their impact on the growing national renewable energy market. The report highlights several key achievements of RPS policies and discusses five current challenges that could threaten the ability of RPSs to continue to be successful. It also recommends two steps states may take to increase the effectiveness of their RPS laws. 

Using State RPSs to Promote Resilient Power at Critical Infrastructure Facilities, by Todd Olinsky-Paul, June 2013. As severe weather events become more frequent, states are increasingly seeking ways to provide power to critical facilities when the electric grid goes down. Clean energy technologies including microgrids, fuel cells and energy storage are an excellent source of resilient power. By adopting appropriate incentives, definitions and safeguards, states could use their RPSs to support increased energy resiliency at critical facilities, while simultaneously promoting the increased deployment of clean energy resources.

The Commerce Clause of the US Constitution and RPSs

The Commerce Clause and Implications for State Renewable Portfolio Standard Programs, by Carolyn Elefant and Ed Holt, March 2011. This major report explains the applicability and effect of the interstate commerce clause of the US Constitution on a state's approach to the design of an RPS. The report also identifies and discusses options available to states for structuring RPS programs in a constitutionally compliant manner. 

Commerce Clause Implications of Allco Finance Ltd. Challenges to Connecticut and Massachusetts RPS Program, by Carolyn Elefant, July 2016. This note summarizes the implications of two pending lawsuits that allege that the Connecticut and Massachusetts RPS programs discriminate against out-of-region renewable energy generation and therefore violate the Commerce Clause of the United States Constitution.

Case Summary- Implications for State RPS Programs of Illinois Commerce Commission et al. v. FERC, by Carolyn Elefant, June 2013. A case summary of a Seventh Circuit decision, Illinois Commerce Commission v. FERC, Docket No. 11-3421 (7th Cr. June 7, 3013), presents a series of questions and answers regarding the Commerce Clause and Michigan's RPS, and explains whether any broad location-based restrictions on RPS eligibility are constitutionally vulnerable. 

Commerce Clause Analysis of People v. Nazarian and Solomon v. Hanna, by Carolyn Elefant, March 2014. This analysis of two recent court cases in Maryland and New Jersey provides guidance for states seeking to retain economic benefits of an RPS in-state. The cases did not focus directly on the states’ RPSs, but rather on efforts to increase in-state capacity resources. Nevertheless, because they involve the electric utility sector and the courts concluded that the programs complied with the interstate commerce clause, the cases shed light on ways in which an RPS program can be protected against a constitutional challenge. 

RPS Collaborative Case Note on North Dakota v. Minnesota PUC, by Carolyn Elefant, April 2014. A Minnesota federal district court concluded that a Minnesota law, which sought to control carbon emissions from power plants, inappropriately reached beyond the state’s borders to regulate activity in neighboring states. Although this case involves state energy policies and the Commerce Clause of the U.S. Constitution, the reasons the law was determined to be unconstitutional do not apply to most RPS programs.

NREL/LBNL Reports Related to RPS

Both the National Renewable Energy Laboratory (NREL) and Lawrence Berkeley National Laboratory (LBNL) produce many useful reports and other publications related to Renewable Portfolio Standards. Some especially relevant recent reports are listed below. In addition, LBNL has a web page ( which serves as a clearinghouse for all of its RPS-related work.  

U.S. Renewables Portfolio Standards 2018 Annual Status Report, by Galen Barbose, LBNL, November 2018. This annual report published in slide-deck form describes key trends, including recent legislative revisions, RPS policy design features, past and projected impacts on renewables development, compliance with interim targets, and costs.

A Prospective Analysis of the Costs, Benefits, and Impacts of U.S. Renewable Portfolio Standards, by T. Mai, R. Wiser, G. Barbose, L. Bird, J. Heeter, D. Keyser, V. Krishnan, J. Macknick, and D. Millstein, LBNL/NREL, December 2016.The report evaluates the future costs, benefits, and other impacts of renewable energy used to meet current state RPS polices. It also examines a future scenario where RPSs are expanded.

A Retrospective Analysis of the Benefits and Impacts of U.S. Renewable Portfolio Standards, by R. Wiser, G. Barbose, J. Mai, L. Bird, M. Bolinger, A. Carpenter, G. Heath, D. Keyser, J. Macknick, A. Mills, and D. Millstein, LBNL/NREL, January 2016. The report analyzed the historical benefits and impacts of renewable energy used to meet all state RPS policies, in aggregate. It employed a consistent and well-vetted set of methods and data sets.

A Survey of State-Level Cost and Benefit Estimates of Renewable Portfolio Standards, by J. Heeter, G. Barbose, L. Bird, S. Weaver, F. Flores-Espino, K. Kuskova-Burns, and R. Wiser, LBNL/NREL, May 2014. In many states, fierce debates have recently arisen regarding the cost of RPS policies. This report seeks to inform these debates by summarizing available data on the costs and benefits of RPS policies to-date and by highlighting key methodological issues that could be considered.

Beyond Renewable Portfolio Standards: An Assessment of Regional Supply and Demand Conditions Affecting the Future of Renewable Energy in the West, by David Hurlbut, Joyce McLaren, and Rachel Gelman, NREL, August 2013. This report assesses the outlook for utility-scale renewable energy development in the West once states have met their RPS requirements. Most western states appear to be on track to meet their final requirements relying primarily on renewable resources located relatively close to the customers being served. What happens next depends on several factors, including trends in the supply and price of natural gas, greenhouse gas and other environmental regulations, consumer preferences, technological breakthroughs, and future public policies and regulations.

Effectiveness of State-Level Policies on Solar Market Development in Different State Contexts, by D. Steward, E. Doris, V. Krasko, and D. Hillman, NREL, 2014. This report provides insight into which solar policies drive market development in different contexts. The analysis shows that the effectiveness of solar policy is influenced by demographic factors such as median household income, solar resource availability, electricity prices, and community interest in renewable energy. The data also show that it’s the number and the make-up of the policies that spur solar PV markets. This report is part of a larger effort to determine the most successful policy strategies for state governments.

Including Alternative Resources in State Renewable Portfolio Standards: Current Design and Implementation Experience, by Jenny Heeter and Lori Bird, NREL, November 2012. This paper examines state experience with implementing RPSs that include energy efficiency, thermal resources, and non-renewable energy and explores compliance experience, costs, and how states evaluate, measure, and verify energy efficiency and convert thermal energy. It aims to gain insights from the experience of states for possible federal clean energy policy as well as to share experiences and lessons for state RPS implementation.