A Grundfos SQFlex should be sized using the required daily water volume and Total Dynamic Head (TDH), rather than pump power alone. Calculate TDH from the dynamic water level, discharge elevation, required outlet pressure and pipework friction losses. The available solar irradiation and required m³/day should then be used to select the appropriate SQF pump and solar array.

The number of solar panels required depends on the SQFlex model, Total Dynamic Head, daily water requirement, panel wattage and available solar irradiation. Solar array sizing should be based on the complete pumping duty rather than simply matching panel wattage to motor power. The array voltage must also remain within the permitted electrical input range of the SQFlex system.

Grundfos SQFlex pumps can operate from both DC and AC power supplies. This makes them suitable for direct connection to a correctly designed solar PV array while also allowing an AC supply, such as mains electricity or a generator, to be incorporated where required. This flexibility is particularly useful where guaranteed water production is needed regardless of solar conditions.

Additional PV capacity can be useful for increasing pumping hours and improving water production during periods of lower solar irradiation. However, the solar array must remain within the electrical limits specified for the SQFlex pump and control equipment. Particular attention should be paid to the array's open-circuit voltage at low temperatures, when PV module voltage can be at its highest.

For solar-direct pumping systems, daily water demand is often more important than peak flow alone. Establish the required m³/day, Total Dynamic Head and available solar resource before selecting the pump. The system can then be designed to produce the required volume over the available solar pumping period, with a storage tank used to accommodate variations between water production and demand.

Different SQF models are designed to operate across different flow and head ranges. The correct model should therefore be selected from its hydraulic performance at the required duty and expected solar input, rather than simply selecting a larger motor or pump. Borehole diameter, installation depth, required daily volume and available PV power should also be considered when making the final selection.

No. A Grundfos SQFlex can operate directly from a correctly sized solar PV array without batteries. In many installations it is more practical to store water rather than electricity: the pump fills a storage tank while sufficient solar energy is available and the stored water is then used when required. This avoids the additional cost, maintenance and eventual replacement associated with battery storage.

Yes. Grundfos SQFlex pumps are designed to accept both DC and AC power, allowing solar PV to be used as the primary source while mains electricity or a generator can provide an alternative supply. This makes SQFlex particularly useful for installations where solar pumping is preferred but water availability cannot be dependent entirely on weather conditions.

Use the dynamic water level when calculating the actual pumping duty. Static water level is the level before pumping starts, whereas dynamic water level accounts for drawdown while the borehole is being pumped. Total Dynamic Head should include the lift from the expected dynamic water level, discharge elevation, required outlet pressure and friction losses through the rising main, valves and fittings.

The appropriate SQFlex control equipment depends on how the system will be powered and controlled. Components such as the CU202, IO50 and IO101 provide different control, monitoring and power-management functions within an SQFlex installation. Selection should therefore be based on the required power sources, level control, system monitoring and operating strategy rather than treating the controller as a standard accessory for every installation.