Grundfos Solar Water Pump Components

We have put together a dedicated section of all the components we generally specify to go with your Grundfos Sq Flex Solar Water Pump.

The first step (using the chart below) is to calculate the nunber of solar panels you will need to provide the desired flow rate at your vertical head lift. The left column shows total head in feet and meters, the top row shows array wattage/number and suggested type of modules, and the boxes show seasonal pump performance and maximum flow. Select the row with the head (total lift) that most closely matches your application then move across the row to the column that contains the desired daily volume or peak flow rate. Note the grundfos SQFlex Solar Water pump model in that block and wattage of the PV array in that column.

NOTE: Daily volume and flow calculations in the table are based on Fresno, CA data at a 36° fixed tilt. Daily summer volume assumes 7.8  kWh/m2/day of insolation and winter volume assumes 4.7 kWh/m2/day. These figures will need to be adjusted to the local insolation  conditions at the actual installation site.

Most solar water pumping systems will provide significantly more output in the summer than in the winter. The typical flow rate is calculated at 800 W/m2 and can be up to 25% greater under bright conditions. Also, up to 40% more water can be pumped in the summer if the array is on a tracking mount. The output can vary by location and weather patterns, and is not guaranteed.

Once you have calcuated the number of solar panels required and the Model of Grundfos SQflex solar water pump, you can then add the other components. Most people use a top of pole mount for a solar water pumping system. It requires the customer to provide a pole of a certain diameter in the ground so that the Top of pole mount will slip over the top of the pole and can be secured down with the included hardware. We generally specifiy grounding lugs for the solar panels and mount which connects a 6awg bare copper stranded wire to a grounding electrode driven near the array into the ground.

Solar panels are wired in series (positve to negative) for high voltage input to the pump and or controllers. From the solar panel array we would then go to the combiner box using an MC4 extension cable. In the combiner box we would have a 15a breaker rated for 150vdc for up to 3 panels or a 15a 300vdc for up to 6 panels in series for arrays of 8 panels we would suggest two 300vdc breakers in the combiner box. The combiner box would also house a lightning arrestor.

A lightning arrestor is required if you are purchasing the Grundfos extended warranty. From the combiner box you would then take the positive and negative outputs to either one of the Grundfos controllers or direct to the pump itself.

Submersible pump cable would be run from the top of the well head down to the pump. Depending on the distance from your solar panels to the well head you may want to run underground feeder cable (UF wire) to save money and splice in the submersible pump cable at the well head. The connection to the pump would be done with an underwater splice kit.

There are also additional items that are generally available locally and include:

• 6 awg copper stranded wire for grounding solar panels to combiner and then to electrode.
• 8’ Grounding electrode and wire clamp
• Concrete and rebar for the mount hole (we can provide dimensional drawing for hole)
• sch 40 steel pipe for mount
• Screws to mount combiner box and controller to the pole/mount.
• Zip ties to attach MC4 extension cables to mount frame.
• Electrical Conduit to go from solar panels to combiner box and then to below ground
• ??’ 10/2 w/ ground UF wire from combiner box to well head, you could use same sub pump cable although UF wire is cheaper.
• ??" diameter drop pipe to pump,  diameter dependant on pump model.
• 3/8 “ Polypropylene Safety rope (not required if using galv steel pipe)