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Size a Submersible Solar Pump

This guide explains the terms and details required to most accurately size a submersible pump for any given scenario. This way we are able to determine the best pump system and model, enhancing the efficiency while producing the desired results. Below you will find a form you may complete with these details, with which we can calculate the most appropriate/efficient pump for your situation. We may then refer you to the nearest dealer for a quote, purchasing and installation.

Location: The location of installation is required to accurately estimate the solar irradiation available in the area to power the pumping system. This allows us to properly size the solar array and estimate the volume of water that can be pumped per day. We also take into account seasonal weather patterns from our global database to figure the hottest, driest, or rainiest months of the year.

Head: The head is the most important measurement for choosing the right pump. This refers to the amount of pressure the pump will need to provide to lift water from the water surface to the point of delivery. This can be measured as pressure (PSI or Bar), but is usually given as the equivalent pressure of a vertical column of water in feet. There are several measurements of head, which when added together give a total dynamic head (see below). View the pump system diagram for an illustration.

Total Static Head: This refers to the total vertical measurement of head only (lowest level of the water source surface to the highest point of delivery). Total static head is the combination of the static level, draw-down, and additional vertical head above the well. It does not consider any additional pressures in pipe or fittings. Total static head may also be referred to as total lift or vertical head.

Total Dynamic Head (TDH): "Dynamic" head refers to the Total Static Head plus friction losses (due to pipe length, size and fittings). In the form below you can enter the Total Static Head and the additional (horizontal) pipe length and size seperately (if any), and we will calculate the TDH for you.

TDH is calculated by converting friction losses (added pressure) to an equivalent feet of head, and adding this to the total static head. The total static head must take into account the lowest draw-down level of the water source at a specific rate of pumping (the well driller can test the well to determine this) and seasonal change. The depth of the well (bottom) is not a relevant figure for TDH, as the measurement begins from the water surface.

Draw-down level: While the 'static level' refers to where the water level sits while not pumping, the 'draw-down' is the additional drop below the static while pumping. How low the water level goes depends on the rate of pumping compared to the well's rate of recovery. If the recovery rate is greater than the pumping rate, there will be no draw-down, or vice versa.

Source Recovery Rate: This is the recovery-rate (or 'refresh-rate') at which water will return to the well (or other source) while pumping, and is therefore the maximum rate at which water should be pumped to stay consistent with the recovery rate of the well and avoid 'low-source' (when the water level drops too low). We measure this rate in Gallons-per-minute (GPM). In the case of well pumps, the driller usually tests the well to determine this figure. A pump can be sized without this figure based on desired flow, but risks oversizing if the recovery rate is less than expected.

Required Gallons-per-Day (GPD): The volume or water required per day. Because the flow rate of a solar pump varies over the course of a day, we do not calculate based on GPM. Alternatively, if max production is desired a pump can be sized to work up to but not exceeding the Source Recovery Rate.

Season: If the pump system will be used for only a few months of the year, it can be designed to produce the required daily volume for that season only. This way the solar array will be optimized for this period. For example, if a pump will be used only during the summer months, then the solar array can be smaller than if it were designed to produce the same volume all year long. If not specified, the system will be designed to produce the required volume as an annual average.

Size for... This variable accounts for when the Required Gallons-per-day will be achieved: Annual Average: the required daily volume is averaged through the whole year (more in summer, less in winter); Maximum Requirement: the required GPD will be achieved only during the best/sunniest month (maximum required GPD); Minimum Requirement: the required GPD will be achieved during the worst/least-sunny month (minimum required GPD); Driest Month: the required GPD will be achieved during the driest month (the month with the least rain on average);

Temperature: For helical rotor (HR) pumps, the water temperature is important to ensure proper performance. For water that's warmer or colder than average, the right temperature class pump will need to be used. The standard temperature class is 46 - 72°F in North America.

Pump Sizing Form

You may complete the following form with the details necessary to size a pumping system for you. Upon evaluation we will refer you to your nearest supplier to contact you with a quote.

*(denotes required field)
(Somewhere else? Find a distributor near you.)
(Location where pump will be installed. Essential for accurate system design.)
(Click here to view pump system diagram.)
(Total length of pipe from pump outlet to the point of delivery.)
(Size of Pipe Length - if pre-installed)
(Rate at which water will return to the well/source)
(Leave blank of unknown. Typical well temp is 46 - 72°F in North America.)
For pressurized systems: note the pressure required at the pressure tank.