French President Emmanuel Macron has taken a swipe at Donald Trump for withdrawing from the Paris climate agreement.
Mr Macron did not name the US president while speaking at the first meeting of the International Solar Alliance in New Delhi.
However, while hailing the "solar mamas", a group of women trained as solar engineers, he said the women had continued their mission to promote solar energy even after "some countries decided just to leave the floor and leave the Paris agreement".
Mr Trump announced last June that the US was withdrawing from the Paris accord, which aims to slow the rise in global temperature by reducing greenhouse gas emissions.
Heads and ministers of dozens of countries are participating in the daylong solar summit, co-hosted by India and France.
The Alliance is a treaty-based international body for the promotion of efficient exploitation of solar energy to reduce dependence on fossil fuels.
It was launched by India and France on the sidelines of the 2015 Paris Climate Conference.
"Because they (solar mamas) decided it was good for them, for their children, their grandchildren," Mr Macron said.
"They decided to act and keep acting, and that's why we are here, in order to act very concretely."
India and France called for affordable solar technology and concessional finance for promoting solar energy.
The summit will discuss framing regulations and standards, credit mechanisms, crowd funding and sharing of technological breakthroughs to promote solar energy in 121 countries associated with the Alliance.
The member countries are fully or partially between the Tropics of Cancer and Capricorn.
Indian Prime Minister Narendra Modi called for a unified effort for promoting solar energy and said the Alliance would help to achieve greater global energy security.
"Promoting its development and use can bring prosperity for all and can help reduce the carbon footprint on Earth," Mr Modi told the summit.
"If we want the welfare of planet Earth and of the whole humanity, I am confident that we can come out of our personal confines and like a family, bring unity in our aims and efforts (to promote solar energy)."
- Press Association and Digital Desk