The funding, which is expected to help the Indian government to expand renewable energy access, comprises $330m from ABD while the remaining $170m will be from the ADB administered multi-donor Clean Technology Fund.

The loan will be used by the Punjab National Bank to fund various developers and end users to install rooftop solar systems throughout India.

ADB's South Asia Department finance specialist Anqian Huang said: "There is huge potential for India to expand its use of solar rooftop technologies because of the sharp drop in the price of solar panels, meaning the cost of producing solar energy is at or close to that from fossil fuels.

"Sourcing more solar energy will also help India meet the carbon emissions reduction target that it has committed to as part of the recent global climate change agreement."

Under the Jawaharlal Nehru National Solar Mission, India aims to increase its overall solar power energy generation to 100GW including 40GW from solar rooftop systems by 2022.

Additionally, the funding is expected to reduce 11 million tons of greenhouse gases over the average 25-year operational life of the solar rooftop systems.

As part of the 2015 Paris climate agreement, India has set a carbon emission reduction target to 33% compared to 2005 levels. It also intends to increase the non-fossil-fuel-based power generation capacity to 40% of installed power capacity by 2030.

Image: A typical solar rooftop system has 25-year operational life. Photo: courtesy of Asian Development Bank.