Presently, the unutilized roofs for roof top plant, barren and low vegetation land for ground mounted systems and Building Integrated Solar PV Plants have been using these unutilized locations for solar plant installation as these require large space for installation of power plant.
Hence, this is a great opportunity to tap unutilized area of Canal top and Canal bank for power generation through solar PV plant. There are few other unutilized locations like stretches of Canals, nearby area of Railway lines which can also be used for solar plant installation. From the above locations, canal tops are getting popular as these locations, along with utilization of canal can save the water evaporation during the hot, sunny and windy environmental condition. Following are the benefits by installing canal top solar power plants:
- Saving water from evaporation
- Utilization of canal top for installation
- Infrastructure development in nearby vicinity of Canal
In first step, straight and parallel stretches must be located across the canal for proper installation of PV arrays. There are feet over bridges present in some trenches of canal needs to be detected before location of installation spots.
In second step, in canal top solar power plants, lots more steps to be taken like shadow casting objects like trees, vegetation available in the area, etc present along the stretch needs to be cut. Stone, pebbles, shrubs, needs to be clear for proper construction. Legal permission must to be taken if any reserved forest is present before cutting.
In third step, for construction, ground level of canal side to be checked before foundation casting for module mounting. This is one of the main issue occur in installation time. And mechanical strength of base, soil type should be surveyed.
In fourth step, technology and type of tracker is chosen. This is based on the climatic conditions, solar irradiation and ease of tracker system. The structures should be easy to work with, as they are to be set up over a slope. Mostly fixed tilt type of modules are selected in canal top solar projects. The structure shall specially design as per Indian Standards to withstand under a wind velocity of 60 m/s.
The methodology of ground –mounted is quite different from canal top projects. Ground-mounted projects are located on the sites with maximum solar radiation to harness maximum solar energy utilizing barren lands, Ashdyke etc unlike canal top projects which aim at water from evaporation and utilizing canal tops. The site is located at such area where it should not disturb reserved forests, natural vegetation, wildlife, nearby villages, ecosystems etc. The construction of canal-top power plants is technically and structurally very different from ground-based solar PV projects as the structures used must not be very heavy so as to prevent it from destructing the foundation of canal. Land survey is done to check whether it can withstand heavy structures
The cost analysis shows that for the same MW of power installation, the installation cost of canal top projects is more than that of ground mounted. The cost breakups are shown below:
Based on the straight stretch of canal, upper width of canal, and ground level difference availability over canal are major factor to decide the following attributes
- Project Cost including specially DC/AC cable Length
- Module Mounting structure Type
- Construction involving columns and rafter throughout canal top which varies with the width of the canal.
The canal tops canal with width from 9 m to 30 m is good for the installation. The structure tonnage is directly proportional to upper width of canal and accordingly costing varies. It has been analyzed that the comparative cost of the canal top project with increasing capacity decreases with the increase of canal width.
Graph 3.1: Project cost with increasing width for same MW project
Graph 3.1 depicts that for same MW, canal project will cost more as compared to ground-mounted project. And with the increasing width the cost of project increases.
Graph 3.2: Ratio of project cost to increasing canal width
Graph 3.2 depicts that ratio of cost of project with respect of increasing width of canal top reduces. Hence for larger width, construction cost as compared to be smaller with will be less and more modules can be installed as larger area is available. Hence, there will be more power generation.
The canal tops solar PV projects are initiated with special purpose unlike ground-mounted PV projects.
- Utilization of area for solar power generation
- Saving of water from evaporation in hot climate condition
- Performance improvement of power generation through solar due to cooling effect below the module.
- Employment opportunity for local.
- Reducing temperature losses and heat losses.
- Designing Issue:As PV panels have to be aligned in a uniform way, it would get difficult to achieve the same over a canal which would be curvaceous and changes its direction over a length.
- Structural Steel Cost: As the structures would get base support only from its two ends it needs to be much stronger than in case it would have been installed on land, thus adding more cost.
- Power Evacuation: Power evacuation of small capacity over a long path would be difficult and costly due to increased cable costs.
- Safety of system: System spread over such a large length cannot be protected by boundary walls or fencing, thus security concerns are very major in such cases.
The canal top solar projects have quite wider scope. As far as these aims are concerned i.e. Utilizing canal tops, power generation, the panels are built over the canal is meant to ensure that around million litres of water does not evaporate. This is one of the efficient and cheapest ways of land use for solar installation.