Solar Storage for Water Pumps and Productive Loads: What to Assess

Measure the pumping task, not only the motor rating

Record the water demand per day, required delivery times, source and destination, vertical lift, pipe length and diameter, and the pump's voltage, phase, running power and starting characteristics. A pump's energy use depends on the water task and operating conditions, so the motor nameplate by itself is not enough to size the full system.

For some water-pumping applications, storing water in a tank can be considered alongside storing electricity. A direct solar-pumping arrangement may suit a different duty than a battery-backed electrical system. Compare the options for the site's water demand, weather, operating schedule and service capability rather than assuming every pump needs a battery.

Decide what must keep operating and when

If the pump must run at night or during a grid outage, state the required hours and the acceptable interruption. If pumping can happen during sunny periods, say so and explain how water will be stored and delivered when the pump is off. Also list other loads that may operate at the same time, such as refrigeration, workshop tools or communications equipment.

Motor starting current, inverter surge capability, cable sizing, controls and protection need to be reviewed as part of the complete installation. Have a qualified installer check the pump and system documentation before selecting an inverter or battery.

Prepare a useful request for a system review

• Share the pump data plate, water-demand estimate, site location, operating schedule and any existing tank or solar equipment details.
• Ask for assumptions about seasonal solar availability, storage or backup duration, protections and maintenance access.
• Confirm whether the proposal covers the pump, controller, battery, inverter, installation, commissioning, spares and local service.