A global study has found that India is the most cost-effective country for generating rooftop solar energy at USD 66 per megawatt-hour, while the cost in China is marginally higher at USD 68 per megawatt-hour. Due to the lower cost, rooftop solar photovoltaics (RTSPV) technology, such as roof-mounted solar panels used in homes, and commercial and industrial buildings, is currently the fastest deployable energy generation technology.


  1. This, according to this global study, is projected to fulfil up to 49 per cent of the global electricity demand by 2050.
  2. Over the past decade, the massive drop in deployment cost coupled with policy-driven initiatives has led to a rapid uptake of RTSPV globally.
  3. Between 2006 and 2018, the installed capacity of the RTSPV has grown from 2.5 gigawatts (GW) to 213 GW.
  4. With an additional capacity installation of 41 GW, RTSPV currently accounts for 40 per cent of the global cumulative installed capacity of solar energy and nearly one-fourth of the total renewable capacity additions since 2018, which is more than the combined new installed capacities of both coal and nuclear.
  5. At the same time, RTSPV technology has shown a steep decline in deployment cost, which ranged between USD 63 and USD 265 megawatt-hour in 2019. It is a reduction of 42-79 per cent over 2010 value.
  6. Rooftop solar photovoltaics account for 40 per cent of the global solar photovoltaics installed capacity and one-fourth of the total renewable capacity additions.
  7. According to the study, India has a significant solar rooftop potential of 1.7 petawatt-hour per year. This is against the country's current electricity demand of 1.3 petawatt-hour per annum.
  8. To understand the electricity generation potential of RTSPV globally and its associated costs, the study mapped 130 million square km of the global land surface area to identify 0.2 million sq km of rooftop area using a machine learning algorithm.
  9. The Rooftop solar photovoltaics technology as a subset of the solar photovoltaic electricity generation portfolio can be deployed as a decentralised system either by individual homeowners or by large industrial and commercial complexes.