Energy

In Tamil Nadu, Rooftop Solar Has the Potential to Outdo Nuclear Power

Tamil Nadu has said its vision is to have an installed solar power generation capacity of 9,000 MW by 2023.

In September, India and Russia announced joint plans to set up 20 nuclear power units in the former over the next two decades.

India’s nuclear establishment believes that the use of nuclear energy can only be good for the country’s industrial development and prosperity. However, nuclear isn’t the only mode of power generation that can make such a claim.

Tamil Nadu is the only state in the country with two nuclear power plants: at Kalpakkam and Kudankulam.

The Kalpakkam complex, commissioned by 1986, has four operating units. Two of them are of 235 MW capacity and two of 600 MW capacity. The complex’s gross generation in 2017-2018 was 1,194 MU (at 64% availability; in 2015-2016, with an availability of 97%, it generated 1,861 MU).

The Kudankulam power plant is the single largest nuclear power station in India. It has two operational units of 932 MW (net) each. In 2018-2019, with an availability of 33%, it generated 2,797 MU.

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Tamil Nadu isn’t the sole beneficiary of the power generated by these plants. In 2016, it required 100,319 MU. It received 99,691 MU from various sources, including state, central and private, and renewable and non-renewable. Of this, nuclear power plants supplied 4,999 MU.

As it turns out, it’s possible to generate this 4,999 MU from rooftop solar panels alone.

On March 31, 2017, Tamil Nadu had the highest installed capacity of grid-connected renewable power (10,562.39 MW), followed by a distant Maharashtra (7,647.60 MW), thanks to wind energy.

According to a 2014 book by S. Gandhi, former president of the Electrical Engineers’ Association of the Tamil Nadu Electricity Board, a 1-MW panel in Tamil Nadu produces 1.5 MU per year on average. This conversion accounts for various factors, including that power production happens only during the day and that production efficiency varies according to the season. Extrapolating from the book, to produce 4,999 MU, Tamil Nadu needs an installed capacity of 3,333 MW.

A 1-kW solar panel over 1,000 roofs can produce 1 MW, so to produce 3,333 MW, we need to install 1-kW solar panels over 3,333,000 roofs. A 1-kW rooftop panel requires about 100 sq. ft. According to state data, there are 2,392,457 buildings in town panchayats alone. Including the total area of all rooftops in Tamil Nadu’s urban centres, and assuming all roofs will generate 10 W/sq. ft., solar power should be easily able to provide the requisite 3,333 MW.

The Government of India and various state governments have consistently presented nuclear power as a safe, sustainable and preferable alternative to coal power. However, while nuclear power plants have very low carbon emissions and have historically caused the fewest fatalities, these advantages are substantially offset by the cost of disposing radioactive waste and an opaque administrative setup in India that has often disprivileged marginalised communities living around power generation complexes.

On the other hand, the biggest downsides of solar power generation are that solar panels lower the productivity of the land they’re setup on, and the batteries used to store power contain toxic materials whose extraction and processing has harmed people in other, often poorer, countries.

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But both issues are quickly resolved in the current example. The question of land productivity doesn’t apply since the panels are to be installed on rooftops. Second, in its solar energy policy published in February 2019, the Tamil Nadu government declared it now has the technology to support grid-connected solar panels on a large scale. This means even domestic solar panels can be connected to the grid, obviating the need for power storage batteries.

According to its policy, the state government says its vision is to have an installed solar power generation capacity of 9,000 MW by 2023.

As of today, the Tamil Nadu government requires every new building erected in the state to be equipped with a rainwater harvesting system. If lawmakers issue a similar mandate vis-à-vis solar panels, at least for apartment complexes and non-residential buildings, Tamil Nadu could soon be self-sufficient about its energy needs, if not produce a surplus it can sell to its neighbours.

Poonkuzhali is a writer and activist based in Chennai.