What affects flowrate?
1. Total lift/slope of land
The greater the vertical distance that the pump needs to lift water, the harder it will be working. That means more energy goes to lifting the water up and your pump won’t be able to lift as much water to that height.
2. Sunshine levels (climate)
The brighter the sun shines, the more energy is available to be captured by the solar panel and turned into pumping energy. So, if you are trying to irrigate in the morning or evening or on a cloudy day when the sun’s rays do not have so much energy, you won’t be able to pump as much water.
3. Pipe sizes (backpressure)
Much like lifting water up higher, backpressure also reduces the amount of water you see coming out of the end of the hose. Back pressure is usually caused by pumping water through a narrow space, which requires more energy because the pump has to compel the water to pass through a small hole. Excessive backpressure can be caused by using a hosepipe which is too small or having kinks or blockages in the hosepipe.
In the user manual we include recommended pipe sizes for maximum efficiency for your situation – take some time to familiarise yourself with this to get the most from your pump.
Different pump designs come with different efficiencies. A low-efficiency pump will use more energy per litre of water pumped as energy is lost through the system. The efficiency of a pump is not usually clearly shown in the pump's marketing material, but it is a question worth asking your pump dealer as it relates to the amount of solar PV required to power the system.
5. Amount of solar PV
Increasing the amount of solar PV with your pump will increase the flowrate as more energy is available for pumping water.
However, it is important not to always assume that the more solar PV pump you generate the higher the pump flow rate will be, as many inefficient solar pumps make up for the loss of energy in the system by working on the PV generation, where you end up paying more without getting any benefit.
6. Never let HP confuse you.
Much like the amount of solar PV, rated horsepower (HP) of pumps can be misleading. For a solar pump, if HP is stated, this usually refers to the maximum solar panel which can be used with the system. If the pump is inefficient and simply using more energy, it doesn’t always mean you’ll get more flow. Always check both HP and stated flowrates.
What flowrate do you need?
Here are six factors that affect the amount of water a pump delivers to your farm.But how do you work out how much water you need to get to your farm in the first place?
1. Land size (area you want to irrigate)
The larger the area you want to irrigate, the more water you will need.
2. The soil on your farm
Clay soils hold water close to the surface, it can become waterlogged easily requires less frequent water application than sandy soils which drain quickly and freely. You can explore more about getting the most from the soil on your farm in our blog.
3. The crops you want to grow
Different crops have different water needs, it is a good idea to have made a plan and know which crops you want to be growing before investing in irrigation.
Examples of water intense crops:
Rice
Cotton
Sugar cane
Soya
Wheat
Example of crops with low water requirements:
Sorghum
Cassava
Sweet potato
Cowpea
Groundnut
If you are unsure about the water requirements for a crop you want to grow, it is a good idea to get advice from an agronomist.
4. Your irrigation application method
You can use a solar pump to apply the water to your crops in several different ways. You can use furrow irrigation, hose pipe irrigation, sprinklers or drip.
If you want to use furrow irrigation, you will need a higher flowrate as this method floods the land quickly, on the other end of the spectrum is drip irrigation which uses a slow drip of water to irrigate over a longer time period. Drip irrigation needs a lower flowrate than furrow.
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