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Can Canal-Top Solar Help India Realise Its Solar Energy Ambitions?

Aug 11, 2020 12:04 PM 5 min read

India is a country that is uniquely well-suited for solar energy.

For starters, it enjoys the ample sunshine – about 300 sunny days a year. For another, it has a large population and growing economy with an insatiable thirst for energy. Then there’s the accelerating push by policymakers towards clean and renewable energy, given the environmental devastation inflicted by coal-fired plants, which generated 72% of the country’s electricity in 2018-19.

So, solar energy is clean and efficient and in high demand.

And India is embracing it with open arms. Asia’s largest solar park was recently opened in Rewa, MP. As of Q1 2020, the country’s solar capacity stood at 36.6GW – which is miles behind that of other countries like China, Japan and the US – but it aims to reach 100GW capacity by 2022.

But as is the case with virtually any economic policy, solar energy comes with its own set of challenges. These include low FDI, issues surrounding taxation and low domestic manufacturing capacity.


India's Land Problem 

One of the main challenges to increasing solar capacity is simply finding enough space for solar panels.

India is a land-scarce country – there’s only so much for an economy of 1.3bn people. Then there’s the high population density – an average of 464 people per square kilometre. And last but not least is the complex maze of land-related laws in the country, which makes land acquisition for any project – solar or otherwise – a long, tedious and expensive process.

So, what’s the solution?

One answer could be investing heavily in roof-top solar panels. But this is an insufficient remedy: it isn’t scalable and sunny space atop buildings is limited as it is.

However, there may be a way to make efficient use of land and generate a lot of energy without having to drown in land-related legalese.

The answer could lie in canal-top solar.


What is Canal-Top Solar?

To see how this would work, let’s head to Vadodara district in Gujarat. There, several canals have been built over centuries, off-shooting from the Narmada river and used primarily for irrigation.

A 750m stretch of canals in this district was identified in 2014 and $18.3m was invested to build solar panels atop the canals. The blue, mirror-like sunlight-catching panels were supported by steel structures while below them the canal snaked its way through the arid land. The panels caught and converted sunlight while protecting the water below from dust and evaporation.  

In the past few years, canal-top solar projects have picked up steam. So far, eight states have commissioned such projects. This includes a 40km-long 100MW $13.9m undertaking along the Narmada.

Can Canal-Top Solar Help India Realise Its Solar Energy Ambitions?
Image of India's first canal-top solar project, which was inaugurated in 2012 in Kadi, Gujarat.


Pros of Canal-Top Solar

The advantages of canal-top solar are numerous. First and foremost, it addresses the land-scarcity problem since the panels are built on already-existing canals. 

The power generated can be used to light up the energy-deficit rural areas of the hinterland, with excess energy being fed to the state grid and sold to distribution companies.

The running water below the panels can cool them naturally, which automatically improves their efficiency. And since the power is generated and largely utlilised in rural areas, transmission losses are minimised.

There’s also the potential – Indian states have a lot of canals. Gujarat alone has 80,000km of them. According to the Gujarat State Electricity Corporation, if 30% of these canals had solar panels covering them, 18,000MW of power could be produced, saving 90,000 acres of land!

The benefits aren’t for solar power generation alone. In states like Gujarat and Rajasthan, canals are indispensable for farmers. But they suffer from evaporation in the simmering summer heat. Covering canals with solar panels cuts down evaporation, leaving more water for crops and people.

In fact, a 1MW canal-top plant can prevent evaporation of up to 9m litres of water per year – saving enough for 2,500 households to be provided with 10 litres of water every day for a year.

What’s more, with the decreased incidence of sunlight, algae growth in canal water is minimised, so there’s less chance of water pumps clogging or toxicity in the water.


Cons of Canal-Top Solar

Canal-top solar has its caveats too. While solar plants are relatively cheaper to install when compared to their coal-fed counterparts, canal-top solar is more expensive than normal solar projects. Strong support structures need to be built, and they have to be galvanised with zinc to prevent rusting because the water below can corrode the steel.

Moreover, not all canals are solar-suitable. They can’t meander too much and they need to be long enough. They also can’t be too wide or the project becomes expensive; and if they’re too narrow, they can’t support enough panels.

The presence of solar panels also limits access to canals for repairing or cleaning silt. Cleaning panels themselves is an obstacle – solar modules tend to have a lifespan of five years, and throughout this time they need to be regularly cleaned of dirt and dust particles for optimum efficiency. And because these structures can be lengthy – often stretching for tens of kilometres – maintaining them can be an uphill task. 

Monitoring them is also a concern, since cameras will have to be installed to check for pilferage.

Despite these challenges, however, the benefits are attractive enough for investment in canal-top solar to pick up. There are many ways to work around its drawbacks. For example, robots are being used to clean panels in some states. Electricity is also being generated from the canal water below, with the combined hydro and solar sources leading to increased output overall.

Power generation by canal-mounted solar panels has steadily picked up over the past decade. And as India seeks to invest more to become a solar superpower, it’s likely that the sight of large blue solar modules mounted on top of long irrigation canals will become a common sight before long.


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