Explained: Why Telangana’s floating solar plant is greener than ground-mounted ones

According to an official release, the 100MW floating solar plant spread over 500 acres of the NTPC’s reservoir at Ramagundam is built at a cost of Rs 423 crore through Bharat Heavy Electricals Limited on an EPC (engineering, procurement and construction) contract. Having moved past fossil fuels to hydro-, nuclear and renewable energy sources for power generation, the NTPC has set a target of producing 60GW (gigawatts) capacity through renewable energy sources, constituting nearly 45 per cent of its overall power generation capacity, by 2032.

What are floating solar plants?

Solar plants or solar farms can be either ground-mounted or set up on the surface of waterbodies. Though these floating farms are a bit more expensive than the traditional ones mounted on land surfaces, there are advantages as well.

At a time when large tracts of land are unavailable, floating farms do not require land to be acquired for the installation of photovoltaic panels. They are more efficient as the presence of water underneath helps them keep cool. They also reduce water evaporation, thereby saving more water for hydropower generation.

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How are these panels kept floating?

At Ramagundam, the solar modules are placed across 500 acres on floaters manufactured with high-density polyethene material that keeps floating irrespective of water-level fluctuations. The entire spread is divided into 40 blocks, each having a capacity of 2.5 MW. Each of these blocks consists of a floating platform and an array of 11,200 solar modules. The floating platform consists of an inverter, transformer, and a high-tension circuit breaker.

How is the project unique?

This project is unique because all the electrical equipment from the inverter, transformer, high-tension panel to supervisory control and data acquisition are also set up on floating ferro-cement platforms. According to the NTPC, the entire floating system is anchored through special high-modulus polyethylene ropes to the dead weights (concrete blocks) placed in the balancing reservoir bed. The generated power is evacuated up to the existing switch yard through 33KV underground cables.

How does it help the environment?

The solar panels floating on the water surface will reduce the evaporation rate and thereby help water conservation. Also, with a minimum land requirement, mostly for associated evacuation arrangements, available land can be put to better use unlike in the case of ground-mounted solar farms, which require large land surface areas.

At Ramagundam, approximately 32.5 lakh cubic metres per year of water evaporation can be avoided. The waterbody underneath the solar modules helps in maintaining their ambient temperature, thereby improving their efficiency and generation. Similarly, coal consumption of 1,65,000 tons can be avoided per year; carbon dioxide emissions of 2,10,000 tons per year can be avoided, according to the NTPC.

Future expansions

The commercial operation of a 92MW floating solar plant at Kayamkulam in Kerala and a 25MW floating solar plant at Simhadri in Andhra Pradesh were announced by the NTPC earlier. Even at its Ramagundam reservoir, the public-sector undertaking has currently utilised only about 500 acres of the spread to generate 100 MW.

At present, NTPC Ramagundam has a traditional ground-mounted solar farm too, spread across 50 acres along the national highway, generating 10MW power. With land not easily available, an official said there is a scope for expansion to generate another 400 MW in the same reservoir. Meanwhile, the Telangana government is also learnt to be keen on using the technology of floating solar farms at its many mega reservoirs to promote clean energy. The state and the NTPC had held a round of talks earlier.