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Category Name - Leaders Speak22 Aug 2019Back

Rooftop solar power: A bright and clean idea on our terrace There is light at the end of the tunnel and it is lit by the power of the Sun

By Dr. Praveer Sinha
Rooftop solar power: A bright and clean idea on ou

India is finally catching up to rooftop solar (RTS) as a reliable source of power for industries, offices, and homes across the country. At the end of the last financial year (FY19) the total installed capacity of RTS in the country was around 4,375 MW, an impressive 72% jump over the previous year. The rising popularity of RTS within the Indian power sector is also an outcome of the increasing share of renewable or green energy in the country. As of the end of the last financial year, the share of renewable energy (that includes solar, wind and biomass) grew to 22% within the overall installed power capacity of 358 GW or 80 GW in total against 70 GW a year ago of which solar power accounted for 30 GW.

Two factors are driving a stronger adoption of solar power in India. First, the cost of solar power has been falling steeply over the last couple of years to around less than Rs 2.40 a unit, thus consistently inching closer to grid parity (as compared to thermal power produced from coal and gas) against Rs 17 a unit nearly a decade ago. A recent study by TERI and US-based think tank Climate Policy Initiative has predicted the cost of generation of solar power could fall to as low as Rs 1.9 a unit over the next decade.

The second and perhaps a more important reason is the changing consumer behaviour that is increasingly moving towards cleaner sources of energy. New and younger consumers in India today or the 'reflex generation' expect utilities and other similar service providers to raise the standards not just in terms of price competitiveness but also their sustainability from an ecology point of view.

Today, within the larger ecosystem of renewable energy sources, solar rooftops not only offer an economical and clean alternative to conventional energy sources but also delivers reliability i.e., that independence from grid-based energy sources that are prone to load-shedding and other hindrances to a consistent quality of service. Solar rooftops that is looped back into the grid also helps consumers turn into micro-generators of power and thus lower the monthly energy bill consistently.

Not counting the potential savings by selling excess power to the grid, a typical residential rooftop solar can save up to Rs 50,000 per kw a year or around Rs 12.5 lakh with a 25-year lifetime of the installation. 

Rooftop solar has been around in India for some time now with consumers in all four major segments -- commercial, industrial, residential and public sector buildings. In fact, residents in large cities like Bangalore and Delhi (and in several cities that can have severe winters) have for long used rooftop solar to heat water at a relatively lower cost.

Rooftop solar has been around in India for some time now with consumers in all four major segments -- commercial, industrial, residential and public sector buildings. In fact, residents in large cities like Bangalore and Delhi (and in several cities that can have severe winters) have for long used rooftop solar to heat water at a relatively lower cost.

Despite its inherent cost and environmental benefits, adoption of rooftop solar has been low in India. There are two main reasons for this -- one the lack of adequate knowledge about the benefits of rooftop solar and two, the initial cost of installation. Thanks to the changing profile of mass media, with social media playing a major role in influencing consumer behaviour, the first challenge is already being addressed effectively, albeit at a pace slower than it ought to be. However, the initial (capital) cost of rooftop solar for the end consumer is still not within the reach of a larger section of the country. The broad demographics of rooftop solar consumers highlights this better. Only 15% of the 4,375 MW of installed rooftop solar in the country are residential consumers, who are typically more conscious of the initial cost than their counterparts in the commercial, industrial and public sector groups.

The initial cost of rooftop solar varies depends on how much of the energy one would like to generate. Consumers can calculate the cost by the following method:

  • Calculate the approximate load (in watts) for a day
  • Divide A. by 8 i.e. average no. of hours of sunlight in a day
  • Multiply B. by INR 110

For example, an 1800 watts a day usage will need solar panels that can produce 14,400 watts. The cost will be approximately Rs 15,84,000.

Rooftop solar basically comes in three formats -- grid-based, off-grid and hybrid. In the grid-based system, the rooftop consumers are connected to the larger grid that is owned by the local utility. The primary source of power is from the rooftop system and the grid power source is used as a backup, should the rooftop solar fail to generate enough power (usually due to poor sunlight). Off-grid as the name suggests is a standalone system where storage batteries are needed to keep the power flow steady throughout the day. So, energy produced during the day, while is consumed, is also saved in batteries and discharged after the sun has set. One of the important and useful application of these off-grid solar systems is providing access to electricity to underserved people by installing solar based micro-grids with battery storage. Storage batteries come in various types such as Lead-Acid (Advanced Lead-Acid and Lead-Acid Carbon) Batteries, Sodium-Nickel-Chloride Batteries, Lithium-Ion Batteries, Nickel-cadmium, and nickel-metal hydride. Lead-Acid and Lithium-Ion batteries are quite common today, with the latter enjoying the advantages of long cycle life and high recharge rates. These standalone systems help in eliminating the requirement of investing in transmission infrastructure along with minimizing the transmission losses.

Innovations in Rooftop Solar

As solar power moves from the fringes to the mainstream, the costs of products like rooftop solar is also bound to come down. Some innovative financing schemes are also available in the market that allows customisation depending on the type of user and what they can afford. The universal electrification project initiated by the government of India along with emerging innovations in rooftop solar products such as do-it-yourself solar kits is bringing more consumers closer to energy independence. The rising environmental concern that is deflecting consumers away from conventional energy sources has only made the market more conducive to rooftop solar in India.

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