The secondary research process involved comprehensive analysis of regulatory databases, technical standards publications, energy sector reports, and authoritative transportation and environmental organizations. Key sources included the US Department of Energy (DOE) Alternative Fuels Data Center, US Department of Transportation (DOT) Federal Highway Administration, Environmental Protection Agency (EPA) Transportation and Climate Division, European Alternative Fuels Observatory (EAFO), International Energy Agency (IEA) Global EV Outlook and Energy Technology Systems Analysis Programme, International Council on Clean Transportation (ICCT) Global EV Market Analysis, California Air Resources Board (CARB) Zero-Emission Vehicle Standards Database, European Commission Directorate-General for Mobility and Transport (DG MOVE), China Ministry of Industry and Information Technology (MIIT) New Energy Vehicle Infrastructure Division, Japan Agency for Natural Resources and Energy (ANRE), SAE International (Society of Automotive Engineers) Standards Database, International Electrotechnical Commission (IEC) 61851 and 62196 Standards, Institute of Electrical and Electronics Engineers (IEEE) 2030.5 Smart Grid Standards, CharIN e.V. (Charging Interface Initiative) Global Charging Database, Electric Power Research Institute (EPRI) Transportation Electrification Research, BloombergNEF (BNEF) Electric Vehicle Outlook, Wood Mackenzie Electric Vehicle Service reports, and national transport ministry statistical bulletins from key EV markets.
Statistics on EV registrations, data on the deployment of charging infrastructure, standards and interoperability protocols, grid integration studies, utility tariff structures, and policy landscape analyses for inductive/wireless charging technologies, AC charging stations, and DC fast charging systems were all gathered from these sources.