Solar Canals: A Green Solution with a Business Challenge
As one takes a turn while driving through Gujarat’s Mehsana district, a streak of blue cuts across the yellow landscape.
The dry smell of dust warns of an arid zone ahead, and the heat warns of impending summers in this terrain.
The blue line quickly turns grey, with a dense crisscross of steel.
The Sanand Branch Canal is a 750-meter irrigation canal with solar panels on top, making it a one-megawatt (MW) solar power plant.
This pilot project in western India’s Chandrasan village is billed as the world’s first canal-top solar installation.
Launched in April 2012, by Indian prime minister Narendra Modi, who was the then chief minister of Gujarat, the canal top photovoltaic technology (CTPV) garnered attention internationally.
“Solar energy requires a vast expanse of land. With this innovation, we will not need land. The transmission cost will also reduce as canals are near villages, so the consumers are right there. The power generation from CTPV is better because the panels are cooled by the water underneath. With these advantages, energy generation from CTPV will become cheapest in times to come,” said Modi while addressing the media at the inauguration on April 24, 2012.
“Replicating the pilot project can generate 2200 MW from just 10% utilization of branch canals,” according to a brochure from Gujarat State Electricity Corporation Ltd (GSECL), the state-owned entity that carried out the test project.
The pilot site, the Sanand Branch Canal, is part of the Sardar Sarovar Narmada Nigam Limited (SSNNL) project, which has the state’s largest canal network at 63,546 kilometers. According to experts, each kilowatt of power generated by ground-mounted solar panels necessitates 4 to 5 acres of land. If the predicted 2200 MW potential is realized with panels on Narmada canals, 11,000 acres of land would be saved.
Despite the hype, little progress has been made in the field of CTPV after 11 years. SSNNL constructed 20 MW CTPVs along two segments of the Vadodara branch canal between 2014 and 2017. They announced the construction of a 100 MW CTPV in 2019, however, the project never got off the ground.
The expensive cost of mounting structures on which panels are mounted is the primary reason for the delayed progress. “In India, solar power is a competitive market.
” Developers will not take it if it does not make apparent commercial sense,” said Gurpreet Singh Walia, co-founder of Green Ops Private Limited, an Ahmedabad-based solar PV consultancy firm.
CTPV can reduce electricity transmission and distribution losses as generation is closer to the consumption point, thereby strengthening the grid.
“Since canals reach remote areas, they can be doubly used to provide electricity to farmers in those areas for running irrigation pumps. And at a nominal cost compared to large parks,” said Jani.
“The hybrid park in Kutch will need a 250-kilometre-long transmission line for bulk evacuation of power so one can imagine that cost,” the SSNNL official said.
The Gujarat Solar Park in Patan district (also known as Charanka Solar Park), India’s then-largest solar park, was inaugurated five days before the canal’s top solar pilot project in Chandrasan. It is erected on “unused land” in Charanka village, according to the authorities.
Since then, four big solar parks have been built on 77,704 hectares of ‘wasteland’ in Gujarat, including the 30-gigatonne hybrid park in Kutch, which is now under development. This is in addition to the 15 MW solar capacity that was later added to Charanka Park. These parks have a total capacity of more than 32 GW.
However, the ‘wastelands,’ as the government maintains, are what the pastoralists of Gujarat rely on for a living. Large-scale renewable energy parks are now threatening these. “It is a trade-off. CTPV has a high skeleton cost, while ground-mounted solar has a high land cost. When the trade-off is positive for the people and environment, we go for CTPV. But when the companies get land free or at subsidized rates, a different kind of economics is at play,” an SSNNL official told Mongabay India, on condition of anonymity.
Canal solar photovoltaic disadvantages
Because solar panels on canals are higher than those on the ground, a CTPV requires a strong mounting structure. Canal solar photovoltaic disadvantages
Because solar panels on canals are higher than those on the ground, a CTPV requires a strong mounting structure. “The structure must be heavy, or the wind speed above and below the panels will blow them away.”
“The mild steel frame is also zinc galvanized to prevent rusting because it will always be exposed to humidity,” Patel explained.
“The mounting structure accounts for 40% of the total capital cost of a CETP, which is more than the cost of panels,” Patel explained.
A one-megawatt CTPV costs Rs. 15-20 million more to install than a ground-mounted plant. “Steel prices have recently risen due to the Ukraine conflict as well as China’s suspension of production.” Meanwhile, other less expensive alternatives have emerged.
A one-megawatt CTPV costs Rs. 15-20 million more to install than a ground-mounted plant.
“Steel prices have increased recently because of the Ukraine war as well as China stopping production. Meanwhile, other cheaper alternatives have come up like floating solar that requires only floaters made of HDPE and PVC, a type of plastic which is not as expensive,” said a former GERMI scientist who didn’t want to be named as he is employed with another organization now.
According to Walia, the average cost of floating solar is less than Rs. 3 per unit. The cost of power from CTPV exceeds Rs. 4-4.5 per unit, compared to the current solar rate of Rs. 2-2.85. “Because the discoms (distribution companies) pay the same rate for both ground-mounted and CTPV solar, why would a developer invest more?” CTPVs would not be economically feasible until the government gives subsidies, according to Yogesh Sehgal, director of SAM Solar Private Ltd. SAM Solar installed two 2.5 MW projects in the Punjab districts of Ludhiana and Sangrur in 2017. Punjab has a total capacity of 20 MW canal-top solar installations.
The Union Ministry of New and Renewable Energy (MNRE) launched central funding assistance in 2014 at a rate of Rs. 30 million per MW for CTPV and Rs. 15 million per MW for canal bank solar. The scheme, which was supposed to help set up 50 MW of CTPV and canal bank, has now ended, according to Sehgal.
CTPV’s linear format–the solar arrays are spread out in lengths rather than plots–raises electrical and maintenance concerns. “A floating solar occupies four acres of the waterbody, an MW of ground-mounted solar takes up to 2.5 acres (with the latest improved efficiency panels) while an MWp of CTPV on a four-meter wide canal will occupy 2.5 kilometers. All the cables have to be brought to a central control room, increasing the cost of cabling and higher losses” said Walia.
A Megawatt Peak (MWp) is a measurement of the maximum potential output of power produced as direct current (DC) under perfect conditions.
“The only advantage of CTPVs is that the developer has to deal with a single party- there is no botheration of land acquisition, dealing with people, police, and prices,” he said.
According to Jaideep Parmar, Deputy Executive Engineer (Solar) at SSNNL, maintaining a CTPV is time-consuming.
“If there is a wiring fault, 2-3 hours are lost in rectifying it as the technician can’t go below the arrays without safety equipment. All this while, the entire unit has to be shut off. Repairing cracks in the civil structure also becomes difficult with panels overhead,” he said.