Do floating solar panels work better?

Experts point out that there are several advantages of floating solar power plants. The most important is that there is no requirement of land. But these are costlier than traditionalsolar panels, writes Deepanwita Gita Niyogi

Floating solar plants, also called floatovoltaics, are the newest craze in India. The Jharkhand government has approved a 100 MW floating solar plant in Getalsud dam near Ranchi. Another plant having a similar capacity is expected to become operational in the reservoir of Ramagundam thermal power plant in Telangana’s Peddapalli district. It is being developed by the NTPC.

The company has also commissioned a 10 MW floating solar plant at Simhadri, Andhra Pradesh, and additional 250 MW floating solar projects, including the one
at Ramagundam.

Experts point out there are several advantages of floating solar power plants, one being that there is no requirement of land. But these are costlier than traditional solar panels and are large-scale in scope and maintenance. For, the Ramagundam project, the capital expenditure is 450 crore. According to the NTPC, the cost is almost at par with a ground mounted solar project.

Why go for floating panels?

Samrat Sengupta, director, climate change and renewable energy, at the Delhi-based Centre for Science and Environment, said floating solar panels are costly as the racking system needs to have a high corrosion resistance, good load capacity and a long life span for holding the panels in water for more than 25 years.

Manu Maudgal, power lead at the Shakti Sustainable Energy Foundation, a non-profit based in New Delhi, explained that the challenge lies in engineering such modules which are able to handle water and wind corrosion as well as operational maintenance like anchoring and mooring.

But there are benefits too. The most obvious advantage is no loss of land space. “The return on investment of floating solar installations is also higher than ground mounted ones. They yield five to seven percent better output than ground ones due to the natural cooling of the panels, resulting in decreased temperatures and higher efficiency,” Sengupta added.

Explaining the land issue further, Maudgal said that in a country like India, grid-scale photovoltaic solar farms are located in areas where land is either cheaper or available on a contiguous basis. The more we come closer to human habitations, cheap and large parcels of land are, however, difficult to get.

Many of India’s reservoirs, lakes and irrigation canals are suitable for floating solar panels. “To make it attractive, the floating photovoltaic potential in India has been assessed to be close to 300 GW. This potential is estimated assuming only 25-30 percent coverage of the water surface and not 100 percent,” Maudgal pointed out.

Talking of canals, Chhattisgarh is trying to work something out in this direction. Sanjeev Jain, chief engineer at the Chhattisgarh Renewable Energy Development Agency under the state government’s department of energy informed that there has been a revision in the state’s solar policy. A proposal has been passed for expansion from the current 700 MW to 2000 MW by 2022. “We are targeting solar as for wind power development, there is not much exploitable potential in Chhattisgarh,” Jain said.

He added that the state is exploring the possibility of setting up floating solar plants on canals banks and canal tops. In this regard, the Solar Energy Corporation of India Ltd under the Ministry of New and Renewable Energy will analyse the potential for which a proposal has been submitted. In Chhattisgarh, canals come under the water resources department of the state government.

Centralised Vs decentralised

The Ministry of New and Renewable Energy wants to promote decentralised solar plants to make affordable power available in rural areas. In an office memorandum dated December 13, 2019, it enumerated guidelines for the development of decentralised solar power plants in India.

Jain added that floating panels work best for discoms or utility grids whereas mini and micro grids serve rural communities better. Decentralised off grid is always a better option for energy storage and security.

He said a lot of renewable energy work is going on in the rural sector in Chhattisgarh. Solar mini and micro grids are being maintained for rural electrification for the past 15 years.

But Maudgal said utility-scale floating photovoltaics or FPVs, which generate solar power and feed into grids, would gain more traction as compared to distributed ones due to the initial engineering and operational maintenance issues.

FPVs are relatively new in India and also globally. Potential new applications for FPVs closer to communities are being considered such as tanks and ponds. However, such applications face challenges like ownership, obtaining clearances and reliable data availability. That is the reason usually man-made reservoirs and water bodies are the first choice, Maudgal informed.

Since not more than 30 percent of the water surface is covered by FPVs, their environmental impacts are also being speculated. More study is required, Maudgal said. “One thing is clear. As water evaporation from water bodies is to the tune of 30 percent, FPVs can reduce that to an extent, thus making water available for other uses.”

But apprehensions exist that FPVs can trigger a chain of reaction in water bodies, harm aquatic life and lead to a shift in the ecology like the food chain. Other negative socio-economic impacts could be effects on tourism, fishing and navigation, Maudgal added.

Meanwhile, the NTPC is studying the feasibility of installing floating solar panels in the water bodies of its other thermal power stations. It has also signed an MOU with the Damodar Valley Corporation to set up floating solar projects in its reservoirs and pursuing states to allocate water bodies for more such projects.