Irrigation without a power grid: when is a solar pump worth it?
On farms, pastures and orchards there's often no electricity near the well. A solar-powered borehole pump works directly off the panel, without an inverter or fuel. We look at when it can replace a generator.
The classic dilemma of off-grid water supply: an expensive generator with fuel and maintenance costs, or a long, permit-heavy grid extension. A solar pump offers a third way, converting solar energy directly into water delivery, with no battery or inverter required.
The key is the built-in MPPT controller. It matches the motor's speed to the panel's instantaneous output, so the pump runs slower in cloudy weather and at full power in bright sunshine, without stalling or being damaged.
When it's the best choice
- There's no grid connection near the well, or it's very far away.
- Water demand falls during daylight hours: irrigation, livestock watering, or filling a tank, when the sun is out anyway.
- You want trouble-free, maintenance-free operation without fuel logistics.
- You have a tank or reservoir that can buffer daily fluctuations.
What's worth thinking through
For a solar system, the benchmark isn't kW but the daily water volume at a given head. A 400 W borehole pump at around 40 meters of head can deliver several cubic meters of water per day, though the exact figure depends heavily on sunlight and system geometry.
As a rule of thumb, the panel's rated output should be around 1.3 times the motor's rated power. This margin covers losses from heat and diffuse light, and keeps the operating point stable for most of the day.
A system with a storage tank is the most convenient: the pump fills the tank during the day, and the water is used whenever it's needed. That way irrigation doesn't have to be timed around the clouds.
Solar or generator?
Where water demand falls at night or on overcast days, a solar system alone isn't enough, and supplementary power is needed. But where the need is daytime and seasonal, such as summer irrigation, a solar pump pays for itself within a few seasons, after which it delivers water essentially for free.