Skip to main content

Classifying U.S. Solar PV Projects

This article provides a brief overview of how Wood Mackenzie classifies U.S. solar PV projects by offtaker type and system characteristics.

Akansha Singh avatar
Written by Akansha Singh
Updated over a month ago

  1. Photovoltaics: We report PV capacity data in watts of direct current (DC) under standard test conditions. This is the metric most used by suppliers, developers and program administrators. However, some program administrators report data in AC watts, and some utility-scale systems are measured in AC watts. Given that, we assume an 87% DC-to-AC derate factor for systems of less than 10 MWac and a 77% DC-to-AC derate factor for systems greater than 10 MWac based on data from existing systems, conversations with installers, and averages from California Solar Initiative data.

  2. Residential photovoltaic system: A residential PV installation is defined as a project in which the offtaker of the power is a single-family household. Any PV system installed on a homeowner's property that participates in a feed-in tariff program is considered residential even if the offtaker of the power is a utility.

  3. Commercial photovoltaic system: Rather than using a capacity cutoff to differentiate between residential, commercial and utility systems, Wood Mackenzie defines a system according to its contracted power offtaker. A commercial PV installation is defined as a project in which the offtaker of the power is a “non-residential” customer – neither a homeowner nor a utility. The spectrum of offtakers typically includes commercial, industrial, agricultural, school, government and nonprofit customers. Importantly, we exclude customer-sited projects that sell power to a utility through a feed-in tariff or power purchase agreement, as the ultimate power offtaker is the utility and not the onsite customer. Examples of excluded projects include the Qualifying Facilities projects in the Massachusetts SMART program and the REDI program projects in Georgia. These are included in the utilityscale segment. While most commercial solar projects under this definition will be connected behind-the-meter on the customer’s property, there are clearly exceptions such as remotely net-metered projects with non-residential offtakers.

  4. Community photovoltaic system: Community solar projects are those where multiple customers can subscribe to power offtake from a project installed in their community and receive credits on their utility bills. These projects are further subdivided into “third-party-led” community solar, where projects are built and operated by third parties, and “utility-led” community solar, where projects are procured or built by utilities. (See our community solar publications for more details on this distinction). In either case, community solar projects are typically “anchored” by commercial customers, but this can vary depending on the program structure.

  5. Utility photovoltaic system: A utility PV installation is a project in which the offtaker of the power is a utility, a third-party power supplier, or a commercial/industrial entity. Projects with commercial/industrial entities as the power offtakers are only considered utilityscale if the projects are front-of-the-meter and connected to the transmission system. These projects are also referred to as “corporate offsite” projects. Utility PV projects also include any PV systems installed on a non-residential customer's property that participates in a feed-in tariff program, in which the system's power is sold to a utility.

Did this answer your question?