Solar borehole pump installation and water supply solutions
Introduction to solar borehole pump installation
Solar borehole pumping is a practical option for supplying underground water to residential properties, farms, schools, commercial premises, livestock facilities, and institutions. A properly designed system uses solar energy to power a borehole pump, which lifts water from underground and delivers it to a storage tank or distribution point.
The performance of a solar borehole pumping system depends on more than the number of solar panels installed. The borehole's sustainable yield, pumping water level, required flow rate, total dynamic head, pipe diameter, pump characteristics, and daily water demand must all be considered before equipment is selected.
Pro-Logic Technologies Limited works with Hydrosol Drilling Solution on borehole-related enquiries and water pumping requirements. The objective is to help customers understand the components, design considerations, installation requirements, and maintenance practices involved in a solar-powered borehole water supply system.
What is a solar borehole pumping system?
A solar borehole pumping system converts sunlight into electrical energy and uses that energy to operate a pump installed in a borehole. In a typical arrangement, solar panels produce direct-current electricity. A compatible solar pump controller regulates the available power and supplies the pump according to the system's design.
The pump lifts water through a rising main pipe to a storage tank. Water can then be distributed by gravity or supplied through a suitable booster pump when greater pressure is required.
Some systems operate with a dedicated DC submersible pump. Others use an AC pump with a compatible solar inverter or variable-frequency drive. The appropriate configuration depends on the pump, motor, controller, water demand, and site conditions.
Main components of a solar borehole pumping system
Solar panels
Solar panels convert sunlight into electricity. Their total capacity must be sufficient for the selected pump and its controller under the site's expected solar conditions.
The installer should consider panel orientation, shading, mounting strength, temperature, cable losses, and the controller's allowable voltage and current. Panels should be connected according to the equipment manufacturer's limits.
Solar pump controller
The controller manages the electrical supply to the pump. Depending on the model, it may provide motor control, operating-status indications, overload protection, dry-run detection, and fault alarms.
The controller must be compatible with the pump's motor type, voltage, current, and power requirements. A controller that is unsuitable for the motor can cause unreliable operation or equipment damage.
Submersible borehole pump
A submersible pump is installed below the water level and pushes water to the surface. Its selection depends on the required flow rate and the total dynamic head against which it must operate.
A pump should not be selected based on horsepower alone. Two pumps with similar motor ratings may produce different flow rates at the same head because their hydraulic designs differ.
Rising main pipe
The rising main carries water from the pump to the surface and onward to the storage tank. Pipe diameter, pressure rating, material, connection quality, and total length influence system performance.
An undersized pipe can create excessive friction losses and reduce the water delivered to the tank. The pipe must also withstand the expected operating pressure and installation conditions.
Storage tank
A storage tank provides a reserve of water for periods when solar pumping is reduced or unavailable. Tank capacity should be based on daily consumption, the timing of demand, expected pumping hours, and the borehole's sustainable yield.
A larger tank is not automatically better for every installation. Tank size should balance water requirements, available space, structural support, and project cost.
Level controls and protective equipment
Float switches or level sensors can help stop pumping when a tank is full. Borehole water-level sensors or controller-based dry-run protection can help prevent the pump from operating when sufficient water is unavailable.
Electrical isolation, suitable overcurrent protection, surge protection, earthing, and weather-resistant enclosures should be considered in accordance with the equipment instructions and applicable electrical requirements.
How solar borehole pump installation works
A successful installation begins with collecting accurate information about the borehole and the intended water supply. The installer should establish the borehole diameter, static water level, pumping water level, sustainable yield, required daily water volume, delivery height, pipe route, and available space for solar panels.
The pump is then selected from its performance curve to meet the required flow at the calculated total dynamic head. The solar array and controller are selected to operate that pump within their specified electrical limits.
During installation, the pump is lowered using appropriate lifting equipment and secured to a suitable rising main. Electrical cables and joints must be appropriate for submersible service. The system is then connected to its controller, solar array, water storage arrangements, and protective devices.
Commissioning should include checking the electrical configuration, controller settings, water flow, delivery pressure where applicable, tank controls, leaks, and operating behaviour. Initial performance should be recorded so that later inspections can identify meaningful changes.
Calculating the water demand
Water demand is one of the most important factors in solar borehole system design. A system intended for a small household will usually have different requirements from one supplying a farm, school, apartment building, or livestock facility.
To estimate daily demand, identify the users and activities that require water. Calculate their expected consumption and add appropriate allowances for cleaning, irrigation, livestock, or other relevant uses.
For example, if a property requires 3,000 litres of water per day and the effective pumping window is six hours, the theoretical average delivery requirement during those hours is:
3,000 litres ÷ 6 hours = 500 litres per hour.
This is approximately 8.3 litres per minute. The pump must be able to deliver the required volume at the actual operating head, and the borehole must sustainably supply that volume.
The example is illustrative rather than a pump recommendation. Real installations require allowance for solar conditions, system losses, changes in water level, and the variation of pump output with operating head.
Understanding borehole depth and water levels
Borehole depth is not the same as pumping lift. The static water level is the depth from the reference point to the water surface when the borehole has recovered and is not being pumped. The pumping water level is the water level while the pump is operating at a particular flow rate.
The difference between these levels is called drawdown. A high drawdown may indicate that the borehole is being pumped at a substantial rate relative to its ability to replenish water.
Pump selection should use the expected pumping water level rather than relying solely on the total drilled depth. The pump's installation depth must also maintain the required submergence and respect the borehole's construction and operating limitations.
Calculating total dynamic head
Total dynamic head represents the total energy per unit weight that the pump must provide to move water through the system. It includes the vertical lift, friction losses in the pipework, and any required delivery pressure expressed as an equivalent water head.
A simplified calculation is:
Total dynamic head = pumping lift + pipe friction losses + required delivery-pressure head.
For example, suppose the pumping water level is 45 metres below the reference point, the tank inlet is 8 metres above that point, and the estimated pipe friction loss is 7 metres. If the water is delivered into an open tank without additional pressure requirements, the approximate total dynamic head is:
45 + 8 + 7 = 60 metres.
This is an illustrative calculation. The actual design must use the relevant elevations, pipe lengths, fittings, flow rate, and any additional system requirements.
For a pressurised system, the required delivery pressure must also be converted into equivalent head. Approximately 1 bar of pressure corresponds to 10.2 metres of water head under standard conditions.
Selecting the correct solar pump
The pump should be chosen using manufacturer performance curves. These curves show how much water a pump can deliver at different heads and operating conditions.
A pump that produces a high flow rate at a low head may deliver considerably less water when required to lift water to a high tank. Therefore, selection must match the pump's expected operating point to the calculated system head and daily water requirement.
The designer should also verify the pump's operating limits, motor compatibility, minimum submergence, water quality requirements, and suitability for the borehole diameter. The pump must not be expected to deliver water faster than the borehole can sustainably provide.
Solar panel capacity and electrical compatibility
The solar array must supply the power required by the pump and controller. The correct panel configuration depends on the pump's electrical input, the controller's permitted voltage range, maximum current, solar conditions, and expected pumping schedule.
Panel capacity should not be estimated from motor horsepower alone. Motor input power, controller efficiency, start-up behaviour, operating voltage, and environmental conditions all affect the design.
Panels connected in series increase array voltage, while panels connected in parallel increase available current. Either arrangement must remain within the controller's electrical limits and the panel manufacturer's ratings.
A qualified installer should verify open-circuit voltage, operating voltage, current, cable size, isolation, and protective devices before energising the system.
Installation safety
Solar borehole installation involves electrical equipment, heavy components, water, and lifting operations. Safe working procedures are essential.
The solar array should be isolated according to the manufacturer's instructions before electrical work begins. DC circuits require equipment rated for DC use because DC arcs can be difficult to extinguish. Submersible pump lifting should use suitable equipment, and workers should avoid unsupported loads and unsafe access around the borehole.
Electrical connections should be protected from moisture, mechanical damage, and unauthorised access. Earthing, surge protection, overcurrent protection, and isolation should be designed for the equipment and installation environment.
Pump installation and electrical testing should be performed by suitably qualified personnel using the correct tools and procedures.
Testing and commissioning
Before handing over a solar borehole system, the installer should confirm that the equipment is installed according to the manufacturer's instructions and that the system operates within its specified limits.
Commissioning checks may include:
- Confirming the solar array configuration and electrical readings.
- Checking controller settings, fault indicators, and protection functions.
- Confirming pump operation and measuring the water flow.
- Checking the pumping water level and ensuring it remains within acceptable limits.
- Inspecting pipes, joints, valves, and the tank inlet for leaks.
- Testing tank-level controls and dry-run protection where fitted.
- Recording the operating conditions for future maintenance.
The commissioning record should state the conditions under which the flow was measured. Pump output can change with solar irradiance, pumping water level, and total dynamic head, so one measurement should not be treated as a guarantee of identical output under all conditions.
Solar borehole pump maintenance
Maintenance helps identify developing faults before they cause a prolonged interruption to water supply. Solar panels should be inspected for shading, dirt accumulation, cracks, loose mounting hardware, and damaged cables.
The pump controller should be checked for fault indications, abnormal operating patterns, and signs of overheating or moisture ingress. Electrical inspections must be carried out safely by qualified personnel.
Water output should be monitored over time. A sustained decline may indicate changes in the borehole water level, pump wear, blocked pipework, leakage, or an electrical problem. Investigating the cause is more effective than replacing components without testing.
The storage tank, valves, float switches, and distribution pipes also require periodic inspection. Maintenance frequency should reflect the site conditions, equipment manufacturer's recommendations, water quality, and the importance of the water supply.
Common solar borehole installation mistakes
One common mistake is selecting a pump based only on borehole depth or motor power. Another is choosing solar panels without verifying controller compatibility. Both can result in a system that fails to meet the required water demand.
Other mistakes include using pipes that create excessive friction losses, ignoring the sustainable borehole yield, placing the pump incorrectly, omitting tank controls, and failing to provide appropriate electrical protection.
Poor commissioning can also conceal problems. Measuring only whether the pump starts is insufficient; the installer should check flow, water level, electrical operation, and protective functions.
A properly designed installation begins with measurements and calculations rather than assumptions.
Solar borehole water pumping enquiries
Pro-Logic Technologies Limited works with Hydrosol Drilling Solution on borehole-related enquiries, including discussions about pump installation, water storage, pumping requirements, testing, and troubleshooting.
Before requesting a system recommendation, prepare the borehole depth, static and pumping water levels if available, borehole yield, intended daily water demand, tank height, delivery distance, and any existing pump or controller details. This information helps determine which further measurements and calculations are required.
Contact: 0723763173
Website: https://prologictecnologies.co.ke
Discuss your solar borehole water pumping requirements before selecting equipment. Proper system sizing, safe installation, suitable protection, and regular maintenance are important to achieving reliable water delivery.