Data Collection and Validation


Production of REN21’s REC begins with an Expression of Interest form to mobilise contributors. The data collection process then involves the following elements:

1. Global tracking database. The REC team compiles data on city-specific indicators, especially targets and policies, building mostly on existing consolidated datasets at the global or regional level.

2. Open city questionnaire. In the city questionnaire, contributors from around the world submit data on renewable energy in their respective cities or cities of interest. This covers information about technology and market trends, targets and policy developments, investment, citizen participation and other local developments. Each data point is provided with a source and verified independently by the REC team.

3. Regional contributors. For each world region, REN21 appoints one principal data contributor to provide city-specific data regarding renewable energy across different sectors and to share an overview of general trends and developments in cities in the respective region. The contributions of other organisations and individuals in each region also are collected, mostly through the questionnaire and peer review feedback.

4. Open peer review. To further collect data and project examples and to ensure that significant developments have not been overlooked, REC-GSR contributors and reviewers participate in an open peer review process that typically occurs halfway through the report’s production cycle. Peer review is open to all interested experts.

5. Expert interviews. REN21’s global community consists of a wide range of professionals who provide their expert input on renewable energy trends ad hoc in specific topics, including through interviews and personal communication with the REN21 REC team and chapter authors. The vast majority of the information is backed up by primary sources.

6. Desk research. To fill in remaining gaps in the report and to pursue new topics, the REN21 REC team and chapter authors conduct extensive desk research. Topics of research can vary among REC editions and depend on emerging topics, important trends and annual availability of relatively recent formal or informal data in cities.

7. Data sharing agreements. REN21 holds several data sharing agreements with some of the largest and most reliable data providers/aggregators in the energy sector. These formal data are used exclusively in some cases or, in others, form the foundation of calculations and estimations presented in the REC.


REN21 ensures the accuracy and reliability of its reports by conducting data validation and fact-checking as a continuous process. Beginning during the first submission of the country questionnaires, data are continually verified up through the design period and until the final report is published. All data provided by contributors, whether written or verbal, are validated by primary sources, which are published alongside the full report.