Solar Water Pump Systems: Complete Guide for Irrigation and Domestic Use

Solar water pumping is one of the most impactful applications of off-grid solar energy, especially in agriculture-dependent regions of the Middle East and Africa. Whether you need to irrigate crops, fill water tanks, or supply a remote village, solar pumping eliminates diesel costs and provides reliable water access.

Two Approaches to Solar Pumping

1. Direct-Drive Solar Pumping

The pump connects directly to solar panels through a pump controller (VFD). No batteries needed — the pump runs when the sun shines and stops at night. Most cost-effective for irrigation where daytime pumping is sufficient.

• Cost: 30-40% less than battery-backed systems
• Maintenance: Minimal — no batteries to replace
• Limitation: No pumping at night, on cloudy days, or during dust storms

2. Battery-Backed Solar Pumping

Uses a Felicity IVPS inverter with battery storage. The pump can run any time — day, night, or during cloudy weather. Ideal for domestic water supply and livestock watering that requires 24/7 availability.

• Cost: Higher due to batteries and inverter
• Flexibility: Pump at any time, even at night
• Best for: Domestic supply, livestock, and time-sensitive irrigation

Pump Types for Solar Systems

Sizing a Solar Pump System

Step 1: Determine Water Requirement

Irrigation: 5-10 mm/day per hectare = 50-100 cubic metres per hectare per day. Domestic: 100-200 litres per person per day.

Step 2: Calculate Pump Power

Power (W) = Flow (m3/h) x Head (m) x 9.81 / Pump efficiency

Example: 5 m3/h, 30m head, 60% pump efficiency: 5 x 30 x 9.81 / 0.60 = 2,453W pump

Step 3: Size Solar Array

For direct drive: Panel watts = Pump watts x 1.3 (safety margin) = 2,453 x 1.3 = 3,189W of panels

For battery-backed: Size according to daily energy consumption plus battery charging requirements.

Cost Comparison: Solar vs Diesel Pumping

Solar pumping pays for itself in 1-2 years and saves $20,000-$50,000 over 15 years.