Solar Submersible Water Pump Problems: 5 Faults and Fixes

A solar submersible water pump is a reliable tool for off-grid irrigation, livestock watering and rural water supply. When it stops working, however, most faults are not in the pump itself. In a solar powered system, the photovoltaic panels, the controller and the wiring fail first. This article covers the five most common problems, what causes them, and the fixes you can carry out on site before calling a technician.

Fault Symptom	Most Likely Cause	On-Site Check	Needs Factory Repair?
Pump will not start	Low panel voltage / loose wiring	Measure open-circuit voltage, check polarity and terminals	No
Runs but delivers little water	Dropped water level / head mismatch / blocked strainer	Check well level, compare with flow-head curve, clean strainer	Sometimes
Stops and restarts often	Cloud cover / undersized array / dry-run protection	Clean panels, remove shading, read controller fault codes	No
Water enters pump housing	Damaged cable gland / worn mechanical seal	Lift pump, inspect cable entry, test insulation resistance	Yes
Weak output on cloudy days	Insufficient irradiance / undersized array	Upgrade to MPPT controller, enlarge array size	No

Why Won’t My Solar Submersible Water Pump Start?

A pump that will not start is usually a power problem, not a pump problem. Check the system in this order:

• Panel output. Measure the open-circuit voltage of the solar array and compare it with the voltage range printed on the pump or controller label. Dirt, shade and a wrong tilt angle can cut photovoltaic power below the start threshold.
• Wiring. Loose or reversed connections between panel, controller and pump stop the motor. Re-check polarity and tighten every terminal.
• Controller protection. Most solar pump inverters include low-voltage and overcurrent protection, so the controller may simply be in protection mode. Clear the fault code and retry.

If the pump still does not start, disconnect it and run the motor from another power source to isolate the fault.

The Pump Runs but Delivers Little or No Water

A running motor with little or no water usually points to hydraulics, not electronics:

• Water level. In a well, the water level may have dropped below the pump intake, so the pump runs dry or draws air. Lower the pump or wait for the level to recover.
• Head mismatch. Every model has a rated head. If the well depth or pipe friction exceeds it, the flow drops sharply. Compare your installation with the flow-head table on the product page.
• Blocked strainer or worn impeller. Sand and debris clog the inlet strainer, and abrasive water wears the impeller. Pull the pump, clean the strainer and inspect the impeller.

This is the most common pattern in a solar submersible water pump used for deep well intake: the motor keeps turning, but the delivered flow falls over time. Regular cleaning of the strainer usually restores full output.

The Pump Stops and Restarts Frequently

Frequent stop-restart cycles are the most common complaint in solar submersible water pump installations, and the cause is almost always supply-side:

• Passing clouds. Solar output follows irradiance. A cloud can drop panel voltage below the controller threshold and trigger low-voltage protection.
• Undersized array. If the panels are too small for the pump, the system operates at the edge of its limit all day.
• Dry-run protection. The controller stops the pump when the water level is low to protect the motor from running without water.

Fix the supply first: clean the panels, remove shading, and enlarge the array if needed. Many solar pump systems now use an MPPT solar pump inverter, which tracks the panel voltage and draws more usable power from the same panels, so check the controller settings before you enlarge the array.

Water Leaks from the Pump or Cable Entry

Water entering the cable entry is the most serious problem a solar submersible water pump can develop, because the motor and bearings sit in a sealed housing:

• Cable entry. The cable gland must be tight and the cable undamaged. A damaged sheath lets water reach the motor.
• Sealing rings. The mechanical seal and O-rings wear over time, especially in sandy water.
• Stage joints. Loose bolts between pump stages can draw water in under pressure.

A leaking pump should be lifted and serviced; drying the outside and restarting it is not a fix. If the insulation resistance is low, return the pump for repair rather than risk a short circuit.

Poor Performance on Cloudy Days

Solar power energy is intermittent by nature: output follows sunlight, so a cloudy day means less water. This is expected behavior, not a fault. The Food and Agriculture Organization (FAO) stresses that these systems need adequate management to stay reliable. To improve weak-weather output:

• Enlarge the photovoltaic array so low irradiance still meets the start threshold.
• Use an MPPT controller, which keeps drawing maximum power in weak light.
• Add a battery or hybrid option if you need pumping before sunrise or after sunset.

For off-grid projects, size the array for the worst season, not the average one.

FAQ

Q1: How do I know if my solar submersible water pump is broken?

Start with the power side: measure panel output voltage and check the controller fault code. If power reaches the controller but the motor does not turn, the pump itself is likely faulty.

Q2: Can a solar submersible water pump work on cloudy days?

Yes, but output drops with irradiance. An MPPT controller improves weak-light performance. For consistent pumping, size the array for the worst season, not average sunshine.

Q3: How often should I clean the pump strainer?

In sandy or sediment-heavy water, inspect and clean the strainer every 3–6 months. In clean water, an annual check is usually enough.

Q4: What size solar panel do I need for a submersible pump?

Match the panel wattage to the pump’s rated input power and your daily water requirement. As a rule, the array should provide 1.3–1.5 times the pump’s rated power to account for cloudy days and losses.

Q5: Why does my solar pump keep turning on and off?

Usually the controller trips on low-voltage protection. Check for shading, dirty panels, or an undersized array. Dry-run protection can also trigger this if the water level is low.

Q6: How deep can a solar submersible water pump go?

It depends on the model’s rated head. Common residential and agricultural units handle 50–200 m of head. Check the flow-head table on the product page for your specific model.

When to Contact the Manufacturer

Water inside the motor housing, a burned winding, or a controller fault code you cannot clear are not field repairs. Share your pump model, controller type and fault description, and our team will identify the correct spare part or replacement. Contact us.

HUOPUSOLAR pumps are tested in our performance laboratory, including hydraulic performance, pressure endurance and insulation resistance checks, before delivery. OEM support and bulk supply are available for irrigation and off-grid projects.