How Do You Size a DC Submersible Pump?

Sizing a DC submersible pump starts with head. Measure the distance from the static water level to the highest outlet. Add draw-down during pumping and any pipe losses; the sum is total dynamic head (TDH).

Next, set flow. A small home with two baths and a washing machine usually needs around 30 L/min. Drip irrigation may need only 10 L/min, while a dairy wash line can reach 80 L/min. Write the target beside the TDH.

Check pump curves. Pick a model whose curve meets your flow at the required TDH near its efficiency peak, not at the extreme right edge. Running at mid-curve keeps motor temperature low and saves power.

Find input power at that point. Multiply the watt figure by 1.3 to size solar panels; the extra margin covers controller losses, morning haze, and aged modules. For example, a 750 W load pairs well with a 1 kW array.

Select pipe diameter large enough to keep friction loss under five percent of TDH. Use copper or HDPE rated above maximum pressure. Choose cable gauge that limits voltage drop to three percent, measured from panels or battery to the pump.

Finish by adding a dry-run sensor and a check valve to protect your investment, longevity.