Fuelling the future

India, ranking fourth in the ‘Renewables 2022 Global Status Report’ by REN21, is one of the leading countries in solar energy transition. In less than a decade, its installed solar capacity has increased about 24 times, reaching 71.61 GW in August 2023, as per the monthly report of Renewable Generation by Central Electricity Authority (CEA). This is in line with India’s target of achieving net-zero emissions by 2070 with a short-term target of increasing renewable capacity to 500 GW by 2030. The International Energy Agency has estimated that the energy demand per capita of the Indian consumer has increased from 25 per cent to 37 per cent between 2000 and 2019. The solar installations have indicated a compound annual growth rate (CAGR) of 29 per cent over the past decade, and the Government of India is pioneering this transition through various initiatives such as the National Solar Mission and Rooftop Solar Scheme.

To continue the expansion of India’s solar capacities, demand for substantial land area to locate the large spread of solar panels is bound to increase. According to The Institute for Energy and Financial Analysis (IEEFA) 2021 report ‘Renewable energy and Land Use in India by Mid-Century’, solar photovoltaic could occupy 50,000 to 75,000 km2 of land to achieve its target of net-zero by 2070. The calculations in the report also presume that the amount of land needed for solar could be equivalent to 1.7-2.5 per cent of the country’s total landmass. This may occupy valuable land space which can otherwise be used for other purposes such as forestry, agriculture, mineral production, building residential areas, roads etc. To overcome this, India needs to integrate innovative renewable technologies such as floating solar panels into its green energy efforts.

Floating solar panels

Floating solar panels, as the name suggests, float on the surface of man-made water bodies such as reservoirs, quarry lakes, canals, etc. hence, do not occupy valuable land space. The major components include solar panels, pontoons/floating structure on which the panels are placed, mooring system consisting of mooring line, anchor and connector to support the panels, inverter to convert DC into AC, and transmission systems to deliver electricity.

China, South Korea and India are in the process of developing high floating solar installation capacities. China recently completed its 320 MW Dezhou Dingzhuang photovoltaic (PV) floating solar project, which is part of a larger renewable energy project also including a 100 MW wind farm. South Korea is also planning a 1200 MW Saemangeum floating solar project in North Jeolla, which is to commence in 2024.

In India, the first floating solar photovoltaic power plant of 10 kW capacity was set up in Rajarhat, Kolkata in 2015 by the Ministry of New and Renewable Energy (MNRE). Currently, India has more than seven major floating solar projects. NTPC Ramagundam solar power plant in Telangana having 100 MW capacity is currently the largest floating solar project of the country. Rewa Ultra Mega Solar Ltd. (RUMSL) is in the process of building India’s largest floating solar project having 600 MW capacity, in two phases, on the Omkareshwar dam on Narmada river in Khandwa, Madhya Pradesh.

Floating solar advantages

The biggest advantage of developing floating solar projects is that they are not constrained by the availability of land for installation and functioning. Given the competing demands on land due to the growing population of India, the required land supply for solar power installation may not be available. This is where floating solar technology can prove to be useful. A study undertaken by The Energy and Resources Institute (TERI) with support from Energy Transitions Commission (ETC) estimates that around 18,000 km2 of water surface area is suitable for installation of floating solar photovoltaic plants. In addition, covering of the water surface by solar panels reduces the rate of evaporation and helps in water conservation. According to Ministry of Power estimates, the NTPC Ramagundam project alone prevents about 32.5 lakh cubic metres of evaporation per year. Floating solar panel technology can particularly be beneficial for the arid and semi-arid regions of India as it will not only produce clean electricity but would also support water conservation.

Ground- and roof-based solar panel’s effectiveness is sometimes reduced by high temperatures. Floating solar panels do not face this problem as they are cooled by the surrounding water which increases their effectiveness by 10 per cent. Existing hydropower and thermal power plants can also provide space for floating solar on their reservoirs. This is mutually beneficial as it saves the cost of setting up a separate transmission system, since the same can be used by both the solar and hydro plants.

Another advantage of floating solar panels is that they reduce the growth of algae in water. Some of the algal blooms release toxins which increase the treatment cost of water. Shading provided by floating panels can reduce this cost by controlling the algal bloom.

Challenges

The integration of floating solar panel projects in our solar energy infrastructure is essential for fulfilling the needs of a growing economy. This innovation, however, has its own challenges that need to be tackled before its full potential can be realised. Floating solar panels covering the surface of water act like a barrier and do not allow light to penetrate into the water which affects the stratified layer of water. It also prevents the exchange of gases between the water surface and atmosphere.

The cost of establishing a floating solar plant is 15-30 per cent higher compared to roof- or ground- based solar plants. Setting up a 1MW ground-based solar project needs about Rs 3 crore of investment while a floating solar project requires around Rs 5 crore, leading to a higher tariff rate. As per norms fixed by the Central Electricity Regulatory Commission, power generated from land-based solar projects have a tariff range of Rs 2.3-2.9/kWh, whereas power from floating solar projects have a tariff range of Rs 2.94-3.80/kWh. Though, as mentioned earlier, the efficiency of FSPV is generally 10 per cent higher.

Before establishing a floating solar plant, each location must undergo a detailed Environmental and Social Impact Assessment (ESIA) in order to determine site suitability and to study the long-term effects of placing a floating solar panel on the local aquatic ecosystem. Presently, in India, the guidelines for ESIA of floating solar panels are not properly available, thus there is a need for policy makers to develop specified guidelines for assessment of such projects.

Future prospect

Floating solar panel technology has great potential, and can overcome the challenges that constrain the adoption of ground- and roof- top solar PV. However, there is a need for developing a holistic approach to further integrate this technology in India’s solar energy infrastructure. Government initiatives are needed to reduce the cost of installation and streamline the process of project development. This will help us in achieving the country’s green energy goals.

A successful integration of the floating solar technology in the energy mix will help us in fulfilment of India’s green energy commitments and expedite the shift towards renewables and sustainable energy.

Aditya Joshi is a retired IFS and Advisor at Mobius Foundation; Mamta Giri is Project Associate, Mobius Foundation. Views expressed are personal