An amount of $300m will come from ADB and $170m from the multi-donor Clean Technology Fund administered by ADB.
Combined with an additional $300m in subproject equity investment and $200m in loans from commercial banks and other financiers, the entire cost of the Solar Rooftop Investment Program is $1bn.
ADB will also provide an additional $5m technical assistance from the multi-donor Clean Technology Fund, which will be used to train and promote the solar rooftop market.
The financing will be done through India’s commercial bank, Punjab National Bank which will distribute the ADB fund to various Indian developers and end users to adopt rooftop solar systems.
ADB 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."
The recent funding aims to achieve 11 million fewer tonnes of greenhouse gas emissions by using solar rooftop systems for a period of 25 years.
India aims to increase energy generation from solar rooftop systems to 40 gigawatts by 2022.
