Solar Panels on Water

Solar Power panels installed on water make a lot of headlines these days. Solar power plants were popularized in India when a 1 MW solar power plant was built 2-3 years ago on a Sardar Sarover Nigam canal in the state of Gujarat. The chief minister in that state used that solar plant to symbolize his innovation and modern credentials. The solar power plant was considered very successful and a much bigger plant was envisaged over kms of the canal.

The main advantages of solar power panels is that they:

• do not use land in a country where land is scarce. The same argument is being used in Japan where a giant solar power plant is coming over water
• reduce water wastage by evaporation
• increase solar power efficiency as the panels are cooled by the water below.

I don’t think these arguments are strong enough. Note solar power plants do not require fertile land or land with water. Solar power plants can be built in deserts and wasteland and there are millions of acres of such wasteland available. The only thing which they require is connection to the grid which has little relation with the fertility of the land. So the myth of land scarcity is easily dispelled.

The second and third arguments also do not hold much water in my view, given that they are not very strong advantages. The power panel efficiency does not increase dramatically nor does water evaporation decrease strongly enough to justify they higher costs.

Consider the cost of a solar panel plant on water, which costs Rs 10 crore/MW in India these days. This is almost 60% costlier than building a plant on land these days. Also land costs around Rs 5 lakh/MW. So basically you are just offsetting around 2% of the additional costs through savings on land costs. Not big enough in my view.

Solar panel on water will remain a niche segment in my view. Good for political optics but not something which will lead to climate change mitigation or increase in substantial renewable energy. That said, the government has kept aside Rs 250 crores as subsidy for building solar power plants on canals and any government entity or PSU can use the subsidy to build solar power plants on water.