Understanding Renewable Energy Certificates

A renewable energy certificate, or REC, is a market-based instrument that represents the environmental attributes of one megawatt-hour of electricity generated from a renewable source. When a solar panel, wind turbine, or other qualifying generator produces one megawatt-hour of electricity, two products are created: the physical electricity that flows into the grid, and a REC that certifies the environmental benefits of that generation.

The REC system exists because electricity on the grid is fungible. Once renewable electricity enters the transmission system, it mixes with electricity from all other sources and becomes physically indistinguishable. RECs solve this accounting problem by providing a trackable certificate that proves renewable generation occurred.

How RECs Are Created and Tracked

RECs are created when a certified renewable energy generator produces electricity and the generation is verified by an independent tracking system. In the United States, several regional tracking systems manage REC creation and retirement, including M-RETS, PJM-GATS, NEPOOL GIS, and WREGIS.

Each REC is assigned a unique identification number that includes information about the generator, the generation date, and the resource type. When a buyer uses a REC to make a renewable energy claim, the REC is retired in the tracking system, ensuring it cannot be counted twice.

Compliance RECs vs. Voluntary RECs

The REC market operates in two parallel segments: compliance and voluntary. Compliance RECs are purchased by utilities to meet obligations under state renewable portfolio standards. Compliance REC prices vary significantly by state and technology, ranging from under one dollar to over fifty dollars per megawatt-hour.

Voluntary RECs are purchased by corporations and individuals who want to support renewable energy without a regulatory mandate. Voluntary REC prices are generally lower, often ranging from one to ten dollars per megawatt-hour.

Solar Renewable Energy Certificates (SRECs)

Several states have created carve-outs within their renewable portfolio standards that specifically require a portion of renewable generation to come from solar energy. SREC markets have been instrumental in driving rooftop and commercial solar adoption in states like New Jersey, Massachusetts, Maryland, and Pennsylvania.

A homeowner with rooftop solar panels earns SRECs for the electricity their system generates, and those SRECs can be sold to utilities at prices that meaningfully improve the financial return on the solar investment. However, SREC prices are volatile and decline as more solar capacity is installed.

Criticism and Limitations of the REC System

The REC system faces legitimate criticism. The most common concern is additionality. When a company buys cheap, unbundled RECs from an existing wind farm that would have been built regardless, the purchase arguably does not drive any new renewable energy development.

This concern has led many corporations to shift toward power purchase agreements that directly finance new renewable projects. Some companies are going further, pursuing 24/7 carbon-free energy matching that tracks hourly consumption against hourly renewable generation.

Despite these limitations, RECs remain an essential part of the renewable energy market infrastructure. They provide the accounting framework for renewable portfolio standards and give smaller buyers an accessible way to support renewable energy without the complexity of a direct PPA.