water pumping for farms and irrigation
Solar water pumping is an option for farms that need to move underground water to irrigation fields, greenhouses, livestock areas, and storage tanks. A correctly designed solar borehole irrigation system can use available sunlight to pump water during suitable daylight hours and store it for later use.
The best system depends on the farm's water requirements, borehole yield, pumping water level, irrigation method, elevation changes, pipework, and available solar resource. A system intended for a small vegetable garden may require a different pump and solar array from one serving a large commercial farm.
Pro-Logic Technologies Limited works with Hydrosol Drilling Solution on borehole-related enquiries and water pumping requirements. Farmers should assess their water source and irrigation needs before investing in a pump or solar equipment.
Why farms use solar borehole pumping
Farms require water for different activities, including crop irrigation, livestock watering, cleaning, greenhouse production, and domestic use by farm workers. Solar pumping can provide an alternative to grid-powered pumping or diesel generation where site conditions are suitable.
One potential advantage is that the system can operate when sunlight is available without consuming diesel during each pumping hour. Actual savings depend on the system cost, pump efficiency, maintenance, water demand, solar resource, and any backup energy requirements.
Solar pumping may be particularly useful where grid connections are unavailable, unreliable, or expensive to extend. However, solar energy availability varies with weather and time of day. Water storage or an alternative supply may be necessary when continuous water availability is essential.
Assessing farm water requirements
The first stage of design is to determine how much water the farm requires per day and when that water is needed.
For crop production, water demand depends on crop type, growth stage, soil, climate, cultivated area, irrigation efficiency, and rainfall. Livestock demand depends on animal type, herd size, weather, and production conditions. Greenhouses and nurseries have their own watering schedules.
A farm should prepare a daily water budget that accounts for the different uses. If the total requirement is 8,000 litres per day, the designer must determine whether the borehole can sustainably supply that volume and whether the pump can deliver it during the available solar pumping period.
A preliminary calculation is:
Required average flow rate = daily water requirement ÷ effective pumping time.
For example, delivering 8,000 litres over eight effective pumping hours requires an average delivery rate of 1,000 litres per hour, equivalent to approximately 16.7 litres per minute.
This is only a starting point. The pump must produce the required flow at the actual total dynamic head, and the borehole must be capable of sustaining the planned pumping rate.
Evaluating the borehole before installation
A solar irrigation project should not proceed on the assumption that a deep borehole will automatically provide a large volume of water.
The relevant information includes the borehole depth, diameter, static water level, pumping water level, sustainable yield, and available borehole records. If these details are unknown, a suitable assessment and pumping test may be required.
The sustainable yield is particularly important. If the pump removes water faster than the borehole replenishes it, the water level may fall during operation. This can cause the pump to lose output, trigger dry-run protection, or suffer damage if protection is absent or ineffective.
A pump should therefore be matched to both the hydraulic requirements and the water source's sustainable capacity.
Selecting a solar pump for irrigation
Solar borehole pumps should be selected using their performance curves. The required operating point is determined by the flow rate and total dynamic head.
Total dynamic head includes the vertical lift from the pumping water level to the delivery point, friction losses in the pipes and fittings, and any pressure requirement at the irrigation equipment.
For example, a system delivering water into an elevated tank may mainly need to overcome elevation and friction. A system feeding pressurised sprinklers must also provide the required operating pressure at the sprinkler inlet.
The same pump may deliver different flow rates under these two conditions. A pump that produces enough water for a low-pressure tank may not meet the flow and pressure requirements of a sprinkler network.
The designer should also check pump diameter, motor compatibility, permitted operating range, water quality suitability, and the manufacturer's installation requirements.
Drip irrigation and solar pumping
Drip irrigation delivers water through emitters positioned near plant roots. It can reduce unnecessary wetting and may improve water management when properly designed and maintained.
A solar pumping system serving drip irrigation must provide the required flow and pressure for the installed emitters and irrigation zones. Filtration is often necessary to prevent clogging, particularly when water contains suspended solids.
Some borehole pumps cannot directly provide the pressure range required by a particular drip irrigation layout without additional equipment. The design may require a suitable filter, pressure regulator, valves, distribution manifold, or booster arrangement.
The required pressure should be calculated from the irrigation equipment specifications and the elevation differences across the farm. Excessive pressure can damage components, while insufficient pressure can lead to uneven water distribution.
Solar pumping for sprinkler irrigation
Sprinkler irrigation distributes water through nozzles that spray it over the crop area. Sprinklers generally require a defined operating pressure to achieve their intended spray pattern and coverage.
The pump must provide both the total flow needed for the operating sprinklers and the pressure required at the relevant points in the system. Pipe friction, fittings, filters, elevation, and control valves all contribute to the total head.
A solar pump should not be selected using only the maximum flow rate shown in an advertisement. The designer must determine the flow at the required head and confirm that the solar power arrangement can support the intended operation.
Where demand is high, the farm may operate irrigation zones in sequence rather than opening every sprinkler simultaneously. This can reduce the instantaneous flow requirement and allow a smaller pumping system, provided the daily irrigation schedule remains practical.
Water storage for agricultural use
A storage tank or reservoir separates water pumping from water consumption. The solar pump can fill the tank when solar conditions are suitable, while irrigation draws water from storage according to the farm's schedule.
Storage capacity depends on the daily water demand, available pumping hours, expected solar variability, the borehole's yield, and the consequences of water interruption. A farm that can pause irrigation during cloudy weather may need a different storage arrangement from one supporting sensitive crops or essential livestock watering.
Tank volume should be calculated using the farm's actual water budget. The designer should also account for the tank's structural support, inlet and outlet sizes, overflow arrangement, access for cleaning, and safe foundations.
A large tank cannot compensate for a borehole that produces too little water over time. The sustainable water supply must be assessed before deciding how much storage to install.
Solar panel placement on farms
Solar panels should be installed where they receive adequate sunlight with minimal shading. Trees, buildings, silos, and future farm developments can reduce the energy available to the pump if they cast shadows over the array.
The mounting structure must withstand local wind conditions and be suitable for the panel dimensions and weight. Panels should be positioned and secured according to the manufacturer's instructions and the site's solar conditions.
Farm equipment, livestock, irrigation water, and routine agricultural activities should not expose panels and cables to unnecessary damage. The array should be located where inspections and cleaning can be performed safely.
The panel arrangement must also remain within the solar controller's specified voltage and current limits. Electrical design should account for the panels' operating and open-circuit characteristics under expected temperature conditions.
Solar pump controllers for agricultural systems
A solar pump controller manages the available electrical power and the operation of the pump. Depending on the model, it may provide motor control, maximum power point tracking, fault monitoring, overload protection, and dry-run protection.
The controller must match the pump's electrical specifications. Some controllers are designed for particular DC pump motors, while others operate compatible AC motors through a suitable drive arrangement.
Agricultural systems may benefit from level sensors, remote monitoring, or operating-status indicators. These features can help farmers identify a full tank, a low water level, or a controller fault before it causes a prolonged interruption.
Control systems must be installed according to the manufacturer's instructions. Sensors and switches should be connected to designated terminals or compatible interfaces rather than improvised directly into the motor circuit.
Irrigation pipes and friction losses
Pipe sizing has a direct effect on the performance of a solar borehole pumping system. Water flowing through a pipe loses energy because of friction, and these losses generally increase as flow velocity rises.
A pipe that is too small may cause high friction losses, reducing the pressure or flow available at the irrigation field. Larger pipes can reduce friction but cost more and may require different fittings and supports.
The design should consider pipe length, internal diameter, material, fittings, valves, elevation changes, and expected flow rate. The rising main and the irrigation distribution network may require different pipe sizes because they serve different parts of the system.
The pressure rating must be appropriate for the maximum expected operating pressure and any relevant transient conditions. Pipes should be supported and installed to avoid mechanical damage, leaks, and unnecessary stress at connections.
Planning irrigation zones
Dividing a farm into irrigation zones allows water to be distributed according to crop requirements and system capacity. Each zone can be operated at a different time, allowing the pump and solar array to serve a manageable flow demand.
The design should consider crop type, field elevation, pipe layout, required operating pressure, and the number of emitters or sprinklers active at once. Zones should be arranged to minimise uneven distribution and avoid excessive pressure differences.
A farmer should establish an irrigation schedule that reflects crop water needs and the expected pumping capacity. Pumping during the strongest sunlight hours may be useful, but irrigation timing must also consider soil conditions, crop requirements, and practical farm operations.
Where water is pumped into storage, irrigation can be scheduled separately from pumping. This arrangement can make better use of available solar energy while allowing water to be used when crops need it.
Estimating solar array requirements
Solar array sizing must account for the electrical power needed by the pump, controller efficiency, solar resource, panel temperature, shading, and system losses.
The pump's rated motor power alone is not sufficient to determine the exact panel configuration. The electrical input at the intended operating point and the controller's specifications must also be considered.
The system designer should check the controller's minimum and maximum operating voltage, maximum current, allowable array power, and compatibility with the selected motor. Panel series and parallel connections must remain within these limits.
A design should also account for seasonal variation in solar energy. If the farm requires a fixed daily water volume throughout the year, the array and storage arrangements must be assessed for the less favourable operating periods rather than only the best sunny days.
Water quality and irrigation equipment
Borehole water quality can affect crops, irrigation equipment, soil condition, and the long-term operation of the system. Depending on the source, water may contain suspended solids, dissolved minerals, iron, manganese, or other substances that require attention.
A water quality test can help determine whether filtration or treatment is needed. The appropriate approach depends on the measured water characteristics and the intended agricultural use.
Drip emitters are particularly sensitive to clogging. A suitable filtration system, regular flushing, and inspection of irrigation lines can help maintain consistent flow.
Water quality considerations should not be confused with pump performance. A pump can deliver the expected volume while the water remains unsuitable for a particular crop or use. Both hydraulic performance and water quality should be evaluated separately.
Installation planning and safety
A solar irrigation installation requires safe work practices for electrical systems, lifting operations, pipework, and work around the borehole.
Solar panels can remain electrically active in daylight even when part of the system is switched off. Electrical work should therefore follow the equipment manufacturer's isolation procedure and be carried out by qualified personnel using appropriately rated tools and protective equipment.
Submersible pumps should be lowered using suitable lifting equipment and an installation method that protects the cable, pipe, and pump assembly. The pump should not be suspended by its electrical cable unless the manufacturer explicitly specifies a cable designed and approved for that purpose.
The solar array, controller, isolators, protective devices, and cables should be installed to suit the environment and applicable electrical requirements. Exposed connections, unsuitable enclosures, and improvised wiring can create serious hazards.
Commissioning a solar irrigation system
Commissioning verifies that the installed system meets its design requirements and operates safely.
The installer should check the panel configuration, controller settings, electrical readings, protective functions, pump operation, water flow, and delivery pressure where relevant. Tank controls, valves, pipe joints, and irrigation zones should also be tested.
The borehole water level should be monitored during pumping to confirm that the selected operating rate is appropriate. If the water level falls excessively or the pump's output declines, the cause should be investigated before normal operation continues.
The commissioning record should include the conditions under which the measurements were taken. Flow may vary with sunlight, pumping water level, and system head, so measured performance should be interpreted in context.
Maintaining a solar borehole irrigation system
Preventive maintenance should include inspecting solar panels, mounting hardware, electrical connections, controller alarms, pump operation, pipes, filters, and irrigation equipment.
Panels should be cleaned when dirt or dust materially reduces output, following safe access procedures and the manufacturer's recommendations. Cables should be inspected for damage caused by sunlight, animals, machinery, or agricultural activity.
The farmer should keep records of daily pumping duration, water delivered, controller faults, and any changes in flow or water level. These records can help identify developing problems before they cause a major interruption.
Filters should be serviced as required, irrigation lines flushed where appropriate, and valves checked for correct operation. Any electrical testing should be performed safely by qualified personnel.
Troubleshooting low water output
Low output can result from several different causes. The solar array may be shaded or dirty, the controller may be limiting operation, the pump may be worn, or the borehole water level may have fallen.
Pipe leaks, blocked filters, damaged valves, and excessive friction losses can also reduce water delivered to the field. If the pump operates normally but the irrigation system receives insufficient flow, the distribution network should be inspected as well as the pump.
Diagnosis should begin with the controller's status indications and a review of operating conditions. Where appropriate, a qualified technician can measure electrical values, pump current, water flow, pressure, and pumping water level.
Replacing the pump without identifying the cause can lead to repeated failures. Correct diagnosis should distinguish electrical faults, hydraulic restrictions, borehole limitations, and irrigation network problems.
Solar pumping for greenhouses and nurseries
Greenhouses and nurseries may require frequent, controlled watering. Their solar pumping systems should be designed around the crop schedule, irrigation equipment, and available water storage.
Small irrigation zones can help manage flow requirements. A storage tank and suitable control equipment may allow water to be pumped during daylight and delivered according to the crop's watering schedule.
The system should be sized for peak demand and evaluated for periods when solar energy is reduced. Sensitive crops may require backup arrangements or sufficient stored water to avoid damaging interruptions.
Filtration and routine inspection are particularly important where fine emitters or automated irrigation equipment are used.
Budgeting for a solar borehole irrigation project
The project budget may include solar panels, mounting structures, a pump, controller, cables, protection equipment, rising main pipe, tank, irrigation distribution network, labour, testing, and transport.
The cost depends on the required flow rate, total dynamic head, borehole conditions, daily water demand, pipe length, storage requirements, and equipment specifications. Two farms may have very different costs even if they use boreholes of similar depth.
A sound comparison should evaluate the full system rather than comparing panel prices or pump prices alone. Equipment compatibility, availability of spare parts, installation quality, expected maintenance, and the cost of any backup supply should also be considered.
Farmers should request a proposal based on site-specific measurements and a clear description of what the installation includes.
Choosing a suitable installation arrangement
A solar borehole irrigation system can be configured in several ways. Water may be pumped directly to an irrigation network, pumped into a storage tank for later distribution, or delivered through a combination of storage and pressure boosting.
Direct pumping may reduce the need for a large storage tank but ties irrigation operation more closely to the pump's available output. Storage can provide greater flexibility, while a booster pump may be needed if the irrigation equipment requires pressure beyond that available from gravity.
The best arrangement depends on the farm's daily water budget, elevation, irrigation method, solar conditions, and need for water outside daylight hours.
Solar borehole irrigation enquiries
Pro-Logic Technologies Limited works with Hydrosol Drilling Solution on borehole-related enquiries and water pumping requirements. Farmers planning a solar irrigation project should prepare information about the borehole, daily water demand, field layout, irrigation method, storage arrangements, and required operating pressure.
Where records are unavailable, the project may require further assessment before equipment can be selected responsibly.
Contact: 0723763173
Website: https://prologictecnologies.co.ke
A properly planned solar borehole irrigation system begins with water demand, borehole yield, hydraulic calculations, and electrical compatibility. Accurate sizing, safe installation, suitable controls, and regular maintenance help the system deliver water more reliably to the farm.