A solar well pump lets you pull water from your well using sunshine instead of grid power or fuel. It is the backbone of off-grid water for homes, cabins, ranches, and livestock, and a smart backup for anyone who loses water when the power goes out. This guide walks you through choosing and sizing the right Grundfos pump.
SQFlex vs SQ Series: which one?
Grundfos offers two solar submersible lines, and the right choice comes down to your power source.
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SQFlex pumps (like the 6 SQF-3 and 11 SQF-2) run directly on solar, wind, battery, or generator, with no grid required. Choose SQFlex for true off-grid wells and remote sites.
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SQ Series pumps (10 SQ05, 10 SQ07, 15 SQ10, 22 SQ15) run on 120V or 240V AC. Choose SQ when you have grid or inverter AC power and want steady flow and pressure.
The three numbers that size your pump
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Flow (GPM): how many gallons per minute you need. A typical household plans around 8 to 12 GPM; livestock and irrigation can need more.
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Total dynamic head (lift): how far the water travels up and over, in feet. This includes well depth to water, drawdown, and the rise to your tank or house. Grundfos rates each pump by GPM at a given head.
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Power source: solar, wind, battery (SQFlex) or AC (SQ). This decides the line and the controller.
Match the pump to your well
Deeper wells and higher lifts need a pump rated for more head, often at a lower flow. A deep, low-yield well pairs well with a high-head SQFlex like the 6 SQF-3 (up to about 820 ft), while a shallower, higher-yield well can use a higher-flow SQ model like the 22 SQ15-220 (22 GPM). If you are not sure of your well depth or water level, your well driller's report has the numbers.
Build the whole system, not just the pump
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Controller or switch box: SQFlex systems use a controller such as the Grundfos CU202 or the IO101 switch box.
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Solar panels: sized to drive the pump on your worst-case day.
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Pump wire: correctly gauged for the depth and distance.
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Storage tank: so you have water when the sun is not out, which usually means no batteries are needed just for water.
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Float switch: to protect the pump and prevent tank overflow.
Common mistakes to avoid
- Sizing on flow alone and ignoring head, which leaves you short on pressure.
- Undersized wire, which drops voltage and starves the pump.
- Forgetting storage, so you have no water on cloudy days.
Get free sizing help
Tell us your well depth, water level, daily water needs, and power source, and we will spec the pump, controller, wire, and panels together so it works the first time. Shop Grundfos solar well pumps or contact our team.
