The complete guide of Solar powered water pump

The solar-powered water pump is a boon to the farmers.

Agriculture is the primary occupation in most developing countries around the world.

Over 60% of the world’s population depends on agriculture for its survival.

As the Indian farmer mainly depends on the monsoons to irrigate his crops.

If the rain is not on time, the crops will be damaged and the people will suffer.

Global warming has disrupted the ecosystem of the earth.

And climate change is the most adverse consequence of it.

The weather patterns are disturbed and now we are witnessing floods and droughts more frequently than ever.

The rains are delayed, affecting the crop yields in developing countries.

Is there any solution that improves food security, increases crop yield, and reduces poverty?

Yes, the Solar-powered water pumps are the solution for this. They can water crops adequately on time.

Working of solar-powered water pumps

The solar-powered water pumps use the sunlight to pump water to the fields for irrigation.

The main components in any solar-powered water pump are:

• Solar panel
• Pump drive controller (MPPT/VFD)
• Mounting structure and tracking system
• Solar Inverter (It is used when you have an AC motor)
• Water pump (It can be DC or AC)
• Earthing system
• Lightning arrestor
• DC circuit breakers
• Surge protection device
• Water level sensor

The pumping system is a combination of an impeller and a motor.

The impeller drives the water movement, and the motor drives the pump.

The water can be withdrawn from different sources such as wells, rivers, lakes, ponds, or canals to irrigate the fields.

The solar panels absorb the sunlight and convert it into electricity used to run the water pump.

A) Types of water pump based on their input current

Types based on their input current type:

• Direct Current operated
• Alternating Current operated

For DC water pumps, we do not need an inverter between the solar panel and the DC motor.

The PV panel’s DC energy is fed directly to the DC water pump through the pump controller.

The DC pump withdraws water from the well, bore, stream, pond, and canal.

While on another hand, for the AC water pump, we need an inverter that converts the solar panel’s DC power into AC and feeds it to the AC motor pump.

The solar panel’s DC power is fed to the inverter via a Variable Frequency Drive (VFD).

B) Types based on their types of installation

If the water pump is installed on the ground surface, it is called a surface pump.

And when it is installed deep into the water, it is called a submersible pump.

Each type has different characteristics based on its point of installation.

Which type of water pump you need depends on the water depth and the delivery conditions.

a) Surface Pumps:

If the water source is a pond, well, or other sources where the water is shallow, the surface pumps are installed.

The pipe through them goes into the water source.

They withdraw water from the water source and irrigate the fields.

The depth of the pipe from the surface pump into the water to suck it is known as the suction head.

The other end of the surface pump is connected to the second pipe which delivers water into the field and other activities.

The total dynamic head of the surface pump is defined as:

Total Dynamic Head = Suction head + vertical pipe delivery head

In simple words, it is the work done by the surface pump to lift the water to a certain height.

b) Submersible Pumps

Another is Submersible pumps.

These pumps are installed deep into the water level. Hence called submersible pumps.

The motor (DC or AC) is kept in a waterproof enclosure.

These pumps are used to push water onto the ground.

Surface or Submersible solar-powered water pump: Which is better?

There are a few striking differences between the surface and submersible pumps.

Again, which type suits you, depends on the water depth and the delivery conditions.

How much water solar-powered water pump can discharge in a day?

The volume of water any pump can discharge depends on its power (HP), the total dynamic head (we have discussed above), and the sunlight intensity.

The surface water pumps have different discharge capabilities than the submersible water pumps.

The method for calculating peak pump flow rate

Required pump flow rate (m³ per day) 
= Daily water required per day (m³)/Peak Sun Hour

For example, the water demand for the day is 10 m³ and the Peak Sun Hours in that region are 5.

Then the flow rate per hour would be:

= 10 m³/5

= 2 m³ per hour

The sunlight intensity: the main factor for the variation in the output

However, the water output during the day depends on the sunlight intensity.

The sunlight intensity during the varies as follows:

This variation in the sunlight intensity causes variation in the speed of the motor and hence the water output varies throughout the day.

Moreover, the output also varies due to the clouds in the sky.

The clouds prevent the sunlight from falling over the surface of the solar panels.

Hence, the output of the motor is reduced.

Advantages of solar-powered water pumps

Many countries around the world depend on the rainfall for irrigating the crops.

People are forced to use polluting methods of irrigating like diesel generator power pumps, etc.

Also, farmers are forced to use labor-intensive activities like rope and buckets to withdraw water from the wells and irrigate the fields.

The women go far to fetch water from the well and irrigate the fields.

The solar-powered water pumps have many benefits:

1) Economical to operate

The cost of solar has reduced very much in the last decade making it economically attractive.

Now you will see solar panels of the latest technologies such as Mono-PERC, Half-cut, and Perovskite solar panels.

Which are highly efficient and capable of converting maximum sunlight into electricity.

The solar panels are very durable and require very little maintenance cost. You need to wash the solar panels.

2) Eco-friendly

The process of absorbing sunlight and converting it into electricity is completely clean. If I talk about the 5 kW residential solar power system installed in a good sunshine region.

Then it can mitigate up to 7 tonnes of carbon emissions in a year.

3) Useful in remote areas

In the remote areas where the grid supply is inaccessible, it is very difficult and expensive to install grid electricity. The solar-powered water pump is a boon for the farmers and people living in remote areas to fulfill their water needs.

4) Easy to install

The solar water pumps are easy to install.

The solar panels are very mobile and one can install them almost anywhere.

Also, the other components like the inverter, and the water-pumps take less installation time.

5) Easy to maintain

You can maintain solar panels easily by cleaning their surfaces periodically.

What you should look in a solar-powered water pump before buying

• Warranty of the solar panels
• Efficiency of the solar panels
• Safety features like a dry run, reverse polarity, low voltage, and lightening arrestor
• Corrosion-resistant mounting structure
• Right Certifications
• Hassle-free Installation
• Galvanized iron module mounting structure.
• Provision to adjust the module towards the sun so that the solar panels absorb the maximum sunlight every time.

Sizing the solar panels for solar-powered water pump

The number of solar panels required to run the pumps depends on the HP of the pumps.

DC pumps are more efficient as they take DC power directly from the solar panels.

While on another hand, in an AC pump, the DC power is first converted into AC and then feeds into the motor.

There is conversion loss in the process.

Therefore, for the same HP the AC motor requires more solar panels than the DC motor of the same capacity.

For 1 HP DC pump 900 watts solar panels are required to run it efficiently.

1 HP = 746 watts

For 1 HP AC pump, 1200 watts solar panels are required.

Price of solar-powered water pumps

The price of the solar water pumps depends on the following factors:

• Brand
• Type of pump
• Power of the pump
• Energy needs
• Sunlight

The surface water pumps are comparatively cheaper than the submersible water pumps.

The price of 1 HP solar-powered water pump is in the range of ₹ 70,000 to ₹ 1,00,000.

The price of the surface water pumps comes close to the lower range.

However, the price may vary ±10% depending the above-mentioned factors.

Do and Don’t of solar-powered water pumps

• Check the connection periodically and report to the team for any damage you see.
• Always operate the motor with dry hands.
• Clean the modules every morning or evening when they are at the normal temperature.
• Do not replace any modules with modules of other rating and technology.
• The junction box must not be operated by an untrained person.

Conclusion:

Yes, solar can power water pumps with ease.

• The farmers can irrigate their fields timely and adequately.

However, certain points are considered when choosing the right type of solar-powered water pump.

• There are two types of motors: AC and DC
• The water pumps can be classified as surface water pumps and Submersible water pumps
• The solar-powered water pumps are clean, reliable, long-life, easy to maintain, and mitigate carbon emissions from the air.
• The price range of 1 HP solar-powered water pumps is ₹ 70,000 to ₹ 1,00,000.
• A 1 HP DC submersible water pump can discharge around 42,000 to 45,000 liters per day at 30 m head.
• While an AC surface water pump of similar capacity can discharge 40,000 to 42,000 liters of water per day at 30 m head.
• Required pump flow rate (m³ per day) = Daily water required per day (m³)/Peak Sun Hour
• Look for an experienced professional to install the right configuration matching your energy needs and other conditions.