India Leads on Solar PV, But Concentrated Solar Power Stays on the Sidelines

India has built one of the world's largest solar power fleets. Almost all of it is photovoltaic. Concentrated solar power, or CSP, which uses mirrors to focus sunlight and drive a thermal turbine, has barely moved off the drawing board.

Saur Energy raised the question this week: if the country gets so much sun, why is there no real CSP industry to show for it?

The technology isn't new. Spain and the United States have run commercial CSP plants for years. Some of them store molten salt for six to ten hours, letting them sell power well after dark. That's a different product from a solar panel, which stops generating at sunset unless it's paired with batteries.

What India has built so far

India's CSP record is thin. A handful of small plants came up under the Jawaharlal Nehru National Solar Mission, including a 50 MW parabolic trough project in Rajasthan and a compact linear Fresnel plant in Gujarat. Several ran into trouble with output, water use and financing. Others never got past the tender stage.

Meanwhile, solar PV crossed 100 GW of installed capacity, helped by falling module prices, cheap land and a steady stream of auctions. CSP missed that wave.

Why the gap

Cost is the first answer. A CSP plant needs mirrors, receivers, a steam cycle and a thermal storage block. Capital costs run several times higher per megawatt than a PV farm. Indian discoms buy on price, and PV wins that auction almost every time.

Water is the second. Many CSP designs need cooling, and Rajasthan and Gujarat, the obvious sites, are dry. Dry cooling exists but trims efficiency and adds to the bill.

Then there's the supply chain. India makes solar cells and modules at scale. It does not make molten salt receivers, high-temperature oils or the precision mirrors CSP plants need. Almost everything would come from abroad.

Where CSP still makes sense

The case for CSP rests on storage. Grid operators need power at 7 pm, when air conditioners are still running and the sun is down. Lithium batteries can cover that, but they're expensive for long durations. A CSP plant with eight hours of thermal storage can do it with tanks of salt.

That argument has found takers in Chile, Morocco and the UAE. India has studied hybrid designs that pair CSP with coal or with PV, but no large project has been commissioned.

Policy hasn't helped. The National Solar Mission had a CSP component, but it was small and the auctions were slow. Recent renewable energy tenders have focused on PV, wind and battery storage. No dedicated CSP auction has been held in years.

Some researchers argue India should keep the option alive for industrial heat, not just power. Cement, steel and aluminium plants need process heat at 300 to 500 degrees Celsius. Parabolic troughs can deliver that. So far, no Indian plant has tried it at scale.

For now, the sun over Jaisalmer does what it has always done. It warms the sand. The mirrors that could turn that heat into midnight electricity are still mostly on paper.