Ajay Mathur has been the Director General of the International Solar Alliance, a treaty-based organization since 14 March 2021. As of 1st Jan 2025, 122 countries have signed the Treaty.

Prior to his election as the Director General of ISA, Dr. Mathur was the Director General of The Energy and Resources Institute (TERI) 2016 - 2021, and earlier of the Bureau of Energy Efficiency (BEE) 2006 - 2016. He has also been a Dean at TERI, President of the wind-energy company, Suzlon, and Team Leader for Climate Change in the World Bank. He was also the Director of the Green Climate Fund in its foundational phase.

As DG of ISA, Dr. Mathur has built up it’s advocacy, capacity building and project preparation activities. He has led the preparation of reports that are prepared on an annual basis, the creation of national centers for capacity building, and enabling countries to make institutional changes encompassing both regulatory and policy change and project development. He has created a Global Solar Facility with a Payment Guarantee window to attract investment in small solar in Africa (This facility will later be expanded to Asia and Latin America). A Solar X Startup challenge has also been initiated to identify solar startups in the developing world who could generate nationally relevant projects. Till date, the challenge has identified 20 startups in Africa, 30 in Asia-Pacific region, and will identify 20 startup in the Latin America & Caribbean region in 2025. These startups are then put through accelerator workshops on raising finance, enhancing technological capabilities, and in brand building so that some of them become the Amazons of tomorrow.

In addition, Dr. Mathur has led the ISA to bring solar into peoples’ lives through events such as the International Solar Festival, and the private sector CEO Caucus. These activities have served to build ISA’s credibility in enabling solar energy as the energy source of choice.

Earlier, as DG of TERI, he led the Institution’s activities in to the energy transition area and on air quality improvement initiatives, and strengthened its work in the energy and environment policy area, the industrial energy efficiency area, and the development of biotechnological innovations, especially in agricultural applications. These activities resulted in the national (and global) recognition that a transition to carbon free energy was possible in India, while meeting the growing energy needs of its people.

As DG of BEE, he brought energy efficiency into our lives. Through the star labelling programme, both consumers and producers of energy-consuming equipment were able to signal the energy efficiency of their equipment. The periodic increases in the energy efficiency of labels helped in bringing in a culture of innovation amongst producers, and of expectation of enhanced energy efficiency amongst consumers and policy makers. Through the Perform, Achieve and Trade (PAT) programme. BEE targeted large industrial consumers of energy, and enabled the progressive decline of specific energy consumption amongst the industrial sectors who were large users of energy. The PAT programme enabled the large industrial sector in India to grow by more than one-third in a little ever 10 years, while its energy consumption grow