Solar panels for water pumps: wells, irrigation and storage
How to size panels for a submersible or surface pump. Direct solar pumping without batteries: how much, what depth, what flow rate.
Solar water pumping is one of the most profitable and elegant uses of PV: if you pump to an elevated tank, the tank becomes your 'battery'. When the sun shines, you pump; otherwise, gravity-feed. Zero batteries, zero maintenance.
Types of solar pump
- DC submersible pumps: inside the well, ideal for depths of 30-650 ft
- DC surface pumps: next to a tank or stream, lift under 25 ft
- AC pumps with VFD: for large or agricultural installs; need a dedicated solar inverter
How to size: three key variables
To pick the pump and panels you need: daily flow (gal/day), total dynamic head (depth + required pressure in feet), and peak sun hours. With those three inputs, the manufacturer's chart tells you the exact model.
Real example: 100 ft well, 800 gal/day
You need a submersible solar pump like Lorentz PS2-150 or Grundfos SQFlex 5A-7. It runs on 2-3 × 410 W panels (820-1,230 W peak) with no battery. Kit cost: $2,000-3,200. Perfect for small farm, livestock or remote homestead.
Example: 2.5-acre irrigation
Typical flow 8,000-13,000 gal/day. You need a 2.2-4 kW three-phase AC pump fed by 10-18 × 450 W panels and a solar VFD (Lorentz PS2, Grundfos SQFlex, Franklin SubDrive Solar). Investment: $7,000-14,000 — payback in 3-4 seasons vs. diesel.
Why no battery is needed
Your storage tank is your battery. It fills when the sun shines; it drains as you draw. This cuts cost, maintenance and failure modes. Exception: if you must pump at night or need constant 24/7 pressure, a small battery pays off.
If you also need to circulate pool water or live without grid, read the complete off-grid solar system guide.
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