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Solar Water Pumping Systems
All You Need to Know
A solar water pumping system uses energy from solar panels to power a normal electric water pump. Whether your pump is new or old and already running on power from the grid or a generator, a solar system is an attractive alternative solution that can be easily integrated and help you reduce your cost of energy by up to 100%.
Solar pumping systems are durable, reliable, and require little maintenance. Their typical payback period is 4 to 6 years, and if properly installed and maintained they should last for their entire lifespan, which is usually about 20 years.
How it Works
A solar pumping system consists of the following components:
- Solar Panels
- Solar Pump Controller (Inverter)
- Water Pump
- Water piping and storage tank
- Other installation materials (mounting structure, cables, sensors etc.)
- Batteries are Not Required
The system works just like any other pumping system, except that its power source is solar energy. The process is simple and straight forward:
- Solar panels convert sunlight into electricity, usually direct current (DC).
- The solar pump controller converts the DC electricity into AC electricity (240 V, which is the same as what we get from the grid or generator) and feeds it to the pump.
- The AC electricity drives the pump, and it pumps water normally. The only difference is that the pump will run at different speeds based on the intensity of the sun, and this can be observed by the fluctuation of the quantity of water at the outlet as the sun’s intensity changes. A properly designed system ensures that the pump gets enough power to run at the optimal speed for most part of the day, usually 9am to 4pm.
- The pumped water is piped to a storage tank, which is usually located at an elevated position so that water can flow by gravity to the points of consumption. A sensor is usually installed in the storage tank to signal the pump to stop automatically when the tank is full. A properly sized storage tank should be able to store enough water to last the nighttime demand, plus some buffer for the following day in case it turns out to be cloudy and not enough water is pumped. If the tank is undersized, this creates the need to run the pump outside the sun hours to refill the tank, which means the use of power from the grid or back-up generator. Also, if the pump is undersized, it must run for more hours to pump enough water to meet the demand, and if these hours exceed the peak sun hours it means pumping using the back-up power source for the extra hours
What It Costs
Solar pumping systems typically have a 20-year lifespan, and over that period they incur various costs, some at the outset, and others at different times throughout the system lifetime. Consideration of all costs incurred during the system lifetime is often referred to as a life-cycle cost analysis. This analysis is usually a good way to compare solar pumping systems to the conventional options (grid or generator) which usually appear cheaper due to lower initial costs yet have considerable operating costs over the project life.
The key cost elements of a solar pumping system are:
- Initial costs – Capital expenditures (CAPEX) and Installation. These mostly consist of the acquisition of equipment for the solar pump system: solar panels, pump controller, mounting system, wiring, etc. Initial costs also include system design, installation, testing and commissioning.
- Operation and maintenance (O&M). Operation costs are mainly labor costs related to a pumping system’s operation. They can vary widely depending on the system’s complexity and capacity. Maintenance costs comprise all costs incurred in keeping the system functional, including routine activities (e.g., cleaning solar panels) and small repairs to faulty components. System design and construction quality can greatly influence O&M cost. This is where the importance of working with a qualified installer comes in. At Ecolink we believe quality is remembered long after the cost is forgotten.
- Capital replacements. Some major parts of a pumping system have a shorter design lifetime than that of the overall system, hence requiring replacements and incurring of the associated costs. The pump controller for example is an electronic device and will need to be replaced at least once during the project lifespan. The good thing about replacing a component 10-years down the lane is that you get the latest technology to revamp your system, and most likely at a lower price.
Each installation is unique based on its specific requirements. In general, the cost of a solar system that is suitable for your pump will mostly depend on the power rating (kilowatt or horsepower) of your pump’s motor. Other factors include the site location and complexity of the mounting system and electrical wiring.
For illustration purposes the prices below assume that the pump has already been installed and has no power source or is running on power from the grid or generator. The prices are inclusive of the cost of the solar equipment and installation services and exclude the cost of buying and installing the pump.
Cost of Solar Water Pumping Systems | |
Pump Motor Rating | Indicative Price (KSh) |
2.2 kW (3.0 Hp) | 330,000 |
3.0 kW (4.0 Hp) | 450,000 |
3.7 kW (5.0 Hp) | 550,000 |
4.0 kW (5.5 Hp) | 600,000 |
5.5 kW (7.5 Hp) | 820,000 |
7.5 kW (10.0 Hp) | 1,120,000 |
The above prices are applicable to both single phase and three phase pumps. For smaller pumps it’s cheaper to power them from a solar system that also serves the house.
Interested in a Solar Water Pumping System?
Find out more about design, costing, and installation by contacting us today!
