India and France have launched a global alliance to mobilise $1tn worth of investment towards developing solar power around the world, focused on tropical countries that are sun-rich but cash-poor.

The International Solar Alliance aims to have 121 signatories, including the US and China, as well as a long list of developing countries situated between the Tropics of Cancer and Capricorn.

“The vast majority of humans are blessed with sunlight through the year, yet many are without any source of power,” said Narendra Modi, the Indian prime minister on Monday. “We want to bring solar energy into their lives.”

François Hollande, the French President, said: “Countries who have the most sun represent only a small part of the global production of solar power . . . How can we reduce energy inequality? By technology and by financing.”

The members of the alliance will sign a declaration to “undertake innovative and concerted efforts” to reduce the cost of solar financing and the cost of solar technology around the world.

They will also agree to push for new solar projects around the world, with an aim to “mobilise $1,000bn” in funds by 2030 needed for a “massive deployment of affordable solar energy”.

The launch comes on the first day of a two week-long conference in Paris to seek a new global deal to reduce global greenhouse gas emissions, in part by shifting from fossil fuels towards renewable energy.

One of the negotiations’ sticking points is India’s insistence that signatories reaffirm a pledge of $100bn a year from rich countries to poorer ones from 2020, to help with emissions reduction and climate change adaptation.

The Solar Alliance was one of a flurry of funding announcements, with the group of 20 countries including the US, China and India vowing to ‎double their existing combined $10bn of spending on clean energy research over the next five years.

Following the failure of the 2009 Copenhagen summit, the United Nations is placing more weight on the efforts of individual governments to reach agreements, rather than relying solely on an overarching UN agreement.

Norway, Germany and the UK also pledged to deliver more than $5bn over the next five years to support countries committed to reducing deforestation, a significant contributor to global warming.

Over the past few years Mr Modi has made solar power generation a key part of his government’s energy policy, targeting 100 gigawatts of solar power generation by 2022, up from around 4 gigawatts at the moment.

“This day is the sunrise of new hope, not just for clean energy, but for villages and homes still in darkness,” he said on Monday, adding that developing solar power around the world would create “unlimited economic opportunities”.

Gérard Mestrallet, the chief executive of Engie, the French utility and the world’s largest electricity producer, welcomed the initiative and said that he was glad that they were attempting to mobilise the private sector as well.

“The private sector is ready to play its part in this effort,” he said.