Solar Pumps
A solar water pump runs directly from solar panels through an MPPT controller – no grid connection, no inverter and no batteries – and stores water in a tank instead of storing electricity. Sizing one comes down to three numbers: the total head the pump must lift against, the litres you need each day, and the peak sun hours where you live. This guide takes you through each, with worked examples, solar panel sizing and current South African price ranges.
Solar Power
120 W – 1.2 kW
DC pumps, direct from panels
Maximum Head
Up to 180 m
Deep borehole capability
Daily Volume
Up to ~15 000 L/day
At low head, in good sun
Running Cost
None
No electricity, no batteries
SA Sun
4 – 6 peak sun hours
Per day, depending on region
Complete Systems
From about R6 400
Pump, motor and controller, incl. VAT
How a solar pump system works
A solar pump system has fewer parts than most people expect. There is no battery bank and, with a DC pump, no inverter. The panels feed the controller, the controller drives the pump, and the pump fills a tank.
| Component | What it does | What to check |
|---|---|---|
| Solar panels | Convert sunlight into DC power | Array size of at least 1.3 × the pump's rated power; open-circuit voltage within the controller's limit |
| MPPT controller | Tracks the panels' maximum power point, soft-starts and protects the pump | Matched to the pump model and voltage; dry-run protection |
| DC pump and motor | Brushless permanent-magnet motor driving a screw or impeller pump | Flow at your total head, from the performance table |
| Storage tank | Holds the day's water for use at night and on cloudy days | Big enough to carry you through a spell of poor weather |
| Float switch or level probe | Stops the pump when the tank is full | Wired to the controller |
| Cable | Carries DC power from the panels to the controller and down to the pump | Conductor size for the run length – voltage drop matters at low DC voltage |
Store water, not electricity. Batteries are the most expensive and shortest-lived part of any solar system. A solar pump avoids them completely by pumping while the sun shines and letting the tank do the storing. A tank costs a fraction of a battery bank and does not wear out in five years.
Which type of solar pump do you need?
| Your situation | Pump type | Why |
|---|---|---|
| Deep or slow-recovering borehole, household or livestock supply | DC solar screw borehole pump | Positive displacement: high head from low power, steady flow at depth |
| Shallower borehole with good yield | DC solar impeller borehole pump | More flow at moderate head |
| Tank, dam or river at or near surface level | Solar surface or booster pump | Moves water and boosts pressure without a submersible |
| Swimming pool filtration | Solar pool pump | Runs the pool through the sunny hours when it is used most |
| Need to pump at night or in poor weather too | Hybrid or inverter-driven system | Can draw on a second power source when solar falls short |
Screw pumps and impeller pumps behave very differently. A screw (helical rotor) pump traps a fixed volume of water and walks it up the pump, so it produces high head from very little power – ideal for deep, low-yield boreholes. An impeller pump moves more water but loses output faster as head rises. For the full comparison with worked numbers, see the Difful 3DSS solar screw pump guide.
Step 1 – Work out the total head
- Start at the pumping water level – the level the water drops to while pumping, not the static level. Set a borehole pump well below it.
- Add the vertical rise to the tank inlet, including the tank stand and any rise in the ground.
- Add friction loss in the pipe. On a solar system every metre of head costs panel power, so a larger pipe pays for itself.
Total head is the sum. For borehole depth, casing size and setting depth in more detail, see the borehole pump guide.
Step 2 – Work out the daily water need
A solar pump only works while the sun is up, so it is sized on the water you need per day, not per hour. The pump has to deliver the whole day's water during the peak sun hours.
Peak sun hours are the equivalent number of hours of full-strength sunshine in a day. South Africa receives roughly 4 to 6 peak sun hours a day depending on region – highest in the Northern Cape and interior, lowest along the KwaZulu-Natal coast. Use the figure for your area in winter, when it is lowest, and you will have water all year.
Required flow = daily water need ÷ peak sun hours
A worked example: a household and a small garden need 3 000 litres a day from a borehole with a total head of 60 m, in an area with 5 peak sun hours. Required flow = 3 000 ÷ 5 = 600 litres per hour, or 0.6 m³/h at 60 m. You are looking for a solar pump whose performance table delivers at least 0.6 m³/h at 60 m, with margin – and a borehole whose yield comfortably exceeds it.
Read the performance table, not the maximum head. A solar pump's maximum head is where flow stops. Always select at your actual head and required flow. Many solar kits are also rated in litres per day at a stated head – for example so many litres a day at 20 m – which is the most useful number of all, provided the sun hours behind it match yours.
Step 3 – Size the solar panels
- Array power: at least 1.3 × the pump's rated power. The margin covers heat, dust, wiring losses and the fact that panels seldom produce their nameplate rating. A 500 W pump needs at least 650 W of panels.
- Array voltage: the panels' combined open-circuit voltage (VOC) must stay below the controller's maximum, or the controller will trip. Panel VOC rises in cold weather, so check it at your coldest morning.
- Orientation: in South Africa, face the panels north and tilt them at roughly your latitude. Keep them clear of shade from trees, buildings and the tank itself.
- Keep them clean: dusty panels are the most common cause of a solar pump slowly delivering less water.
Two 540 W mono PERC panels, for example, give 1 080 W – comfortably over the 650 W minimum for a 500 W pump. Check their combined VOC against your controller before wiring them in series.
Step 4 – Size the cable
Solar pumps run on low DC voltages – typically 24 V to 110 V – so current is high for the power delivered, and voltage drop in undersized cable eats straight into your water output. The lower the system voltage and the longer the run, the thicker the cable must be. Use the pump manufacturer's cable chart for your voltage, power and run length, and confirm against SANS 10142-1.
Installation essentials
- Protect against dry running. Most solar controllers have built-in dry-run protection; make sure it is enabled and the pump is set well below the pumping water level.
- Fit a float switch in the tank so the pump stops when it is full.
- Hang borehole pumps on a safety rope, not on the pipe or cable.
- Shade and ventilate the controller. Electronics lose life fast in direct summer sun.
- Earth the panel frames and the system, and fit lightning protection in exposed rural sites.
- Size the tank generously so a few cloudy days do not leave you short.
Solar pump price guide
Typical price ranges from our current range, including VAT. Every product listing shows its live price.
| What you are buying | Typical price range |
|---|---|
| Solar borehole system – pump, motor and controller (3-inch, 120 W – 1.2 kW) | R6 400 – R10 100 |
| Solar surface booster pump | R7 400 – R11 300 |
| Solar pool pump (0.5 kW) | from about R8 600 |
| Replacement solar controller | R2 600 – R3 500 |
| Solar regulator | about R375 |
| 540 W mono PERC solar panel | about R1 840 each |
| Complete solar kits including panels (Omega, Watermax) | on quotation |
Price ranges are drawn from our listings at the time of writing and include VAT. Panels, mounting, pipe, cable and installation are extra unless a kit states otherwise.
Shop the solar range
| Category | Ranges |
|---|---|
| Solar borehole pumps | Difful 3DSS · Vega 3" 3HR and 3HRI |
| Complete solar kits | Omega complete systems · Watermax kits |
| Watermax by head | 0–40 m · 0–70 m · 0–80 m · 0–100 m · 0–160 m |
| Surface & pool | Vega solar booster · Vega solar pool · All Vega surface solar |
| Controllers & spares | Solar controllers · Vega solar spares · Solar inverters |
| Solar panels | Mono PERC PV modules |
Frequently asked questions
How does a solar water pump work?
Solar panels produce DC power, which an MPPT controller uses to drive a brushless DC pump. The controller tracks the panels' maximum power point so the pump makes the most of morning and afternoon light. There are no batteries – the pump fills a tank during the day and the tank supplies water at night.
Does a solar pump work on cloudy days?
It keeps working, but at reduced output – in heavy cloud it may slow to a trickle or stop. That is why solar systems are paired with a storage tank sized to carry you through a few poor days, and why the solar array is sized with a margin above the pump's rating.
How many solar panels do I need for a solar pump?
Size the array at a minimum of 1.3 times the pump's rated power. A 120 W pump needs about 160 W of panels, a 500 W pump about 650 W, and a 1 200 W pump about 1 560 W. The panels' combined open-circuit voltage must also stay within the controller's limit.
How much water will a solar pump deliver per day?
Multiply the pump's flow at your total head by the peak sun hours in your area. South Africa receives about 4 to 6 peak sun hours a day. A pump delivering 0.6 m³/h at your head, in an area with 5 peak sun hours, gives roughly 3 000 litres a day.
Does a solar pump need batteries?
No. A DC solar pump runs directly from the panels, and the water is stored in a tank instead. This removes the most expensive and shortest-lived part of a typical solar system.
How deep can a solar borehole pump lift water?
Solar borehole pumps in our range lift up to 180 m, depending on model and power. Screw-type solar pumps are best for deep, low-yield boreholes because they produce high head from low power.
What does a solar borehole pump cost in South Africa?
Complete solar borehole systems with pump, motor and controller start from about R6 400 and run to about R10 100 for a 1.2 kW system, including VAT. Solar panels, pipe and installation are extra. Complete kits that include panels are available on quotation.
Can a solar pump run at night?
A pure DC solar pump only runs while there is sunlight. For water at night you store it in a tank during the day. If you genuinely need to pump at night, look at a hybrid or inverter-driven system that can draw on a second power source.
Which is better for a borehole – solar or electric?
Solar has no running cost and works where there is no grid, but it pumps only in daylight and costs more up front per litre of capacity. Electric pumps deliver more water on demand. For off-grid sites, livestock and domestic supply into a tank, solar usually wins over the life of the system.
Why is my solar pump delivering less water than before?
The usual causes are dirty or shaded panels, a controller in direct sun overheating, a falling borehole water level, a worn pump, or undersized cable dropping voltage. Clean the panels first – it is the most common cause and the cheapest fix.
Not sure which solar pump you need?
Send us your water source, total head or borehole depth and pumping water level, the litres you need each day, and where you are in the country. We will size the pump, the solar array and the cable for you.
Related ranges
- Solar Pumps — the full solar category
- Difful 3DSS Solar Screw Borehole Pump guide — deep-borehole solar in detail
- Borehole Pump Guide — casing, depth and yield explained
- Borehole Pumps — mains-powered borehole pumps, motors and control boxes