Introduction to Floating PV Plant

Sunil Rathi, Director Sales & Marketing
Waaree Energies ltd

Renewable energy sources are of prime importance as they would power our future. Solar energy power plant which utilises the sun’s energy needs adequate space for installation. It is a well-known fact that out of the 510 million Km2 surface area of earth, a mere (appx.) 29% is covered with land.

Additionally (at some locations) the land may be of importance and it may not be feasible to dedicate (some) space for solar energy power plant.

In a country where cities are dense and agricultural land is limited, installing solar power plant (which require huge swathes of land) may not be viable. This is where floating PV power plant can come to our rescue.

Floating PV power plant as the name suggests are floating bodies of solar PV plants on water (Figure 1).

Figure 1: Technical details for floating PV system (Source: Google Images)

The basic components of floating PV system are mentioned below:

1) Floating structure: Also known as Pontoon, the floating structure is a sturdy structure which easily holds the solar panel. It also has enough buoyancy to stay afloat on water while supporting the heavy load.

2) Mooring system: The floating structure is held securely with a permeant structure known as mooring. This halts the free movement of the floating structure in water. The floating structure can be fixed with reference to a point on bottom of waterway eliminating the need to connect to the floating structure to the shore. This can be done with help of anchor mooring.

3) Under water Cabling: This form as an important link between the grid and the solar panels. Due to its usage under water, the cabling may be designed to be shock and/or leakage proof. A typical technical diagram of floating PV system is shown in the figure below:

Figure 2: Technical details for floating PV system (Source: Google Images)

The floating PV system has the following advantages over the ground/ roof mounted solar systems

1) Increased output from system: Various studies have been carried out to understand the output of floating PV system. These studies confirm that there has been an increase in energy generation from such plants. This increase can be attributed to the reduced operating temperature of solar modules resulting from natural cooling from water. Additionally, these systems if installed in huge water bodies may have less settled dust on them resulting in increased energy output from plant. An increase in energy of around 10% to 12% from such system may be realized.

2) Savings of water: Water from water bodies is lost in form of vapour. Installing floating PV plant reduces the water loss due to evaporation. Additionally, cleaning a typical solar power plant require huge amount of water. CEEW estimates that around 7,000 ~ 20,000 litres of water per MW is required in cleaning of plant. A cleaning cycle in power plant may happen more than once a week. Such huge quantities of water may be saved if floating PV system is used. The cleaning water used in floating PV system goes into the water body again which can be reused leading to savings in water and its associated cost.

3) Alternate source of energy at Dams: Dam based reservoir can utilize their water bodies to install floating PV system. Such system may help boost the usage of solar energy during day time. The water saved during day time may be utilized during night time to generate more power reducing dependence on fossil fuel based plants. Additionally, the Ministry of Power had already indicated in its (draft) National Tariff Plan (released in 2016) that it may implement Renewable Generation Obligation (RGO). While the policy is still in draft state, utilizing floating PV may fulfil the generators RGO.

The concept of floating PV is not new to the world. There are various countries in the world like, Australia, China, Japan, UK, etc. which have already installed floating PV plants. India which has adequate water bodies has also tried and implemented floating PV projects. Recently, India’s largest floating solar PV plant standing at capacity of 500 kW was completed in Kerala. It could withstand the variations in water level of 21 meters between summer and monsoon. The country seems to have realized the potential of floating PV system and further capacity addition in same technology can be expected soon.

Weight balancing is one of the important factors in floating PV plants and any reduction in the weight would result in significant savings. In our last blog, we informed you about performance of our Merlin modules. These modules are flexible and come at a reduced weight (when compared to the frame based solar modules). Such modules may be a perfect match for this application. Additionally all our modules are tested stringently and are certified by various international bodies for maximum on field performance. We encourage the use of our modules on both the existing as well as such innovative ideas. Let us all pledge to make solar energy the primary source of energy in the near future.