In South Africa’s sun-soaked irrigation farming regions, more and more farmers are moving away from diesel gensets and Eskom connections. They’re choosing a simpler approach: solar-powered pumps linked to a variable speed drive (VSD), delivering water directly when the sun shines.
No batteries. No inverters. Just panels, a VSD, and a three-phase pump motor doing what the farm needs, exactly when there’s sunlight.
It’s not new technology, but when it works, it works brilliantly.
Irrigation doesn’t need to run around the clock. Centre pivots, draglines and sprinklers all operate on schedules – a few hours in the morning, a few more in the afternoon. Pumping to collector dams is even more flexible: you can store water when the sun is shining and draw from that store when you need it.
This makes solar PV a natural fit. With some planning, you can match your pumping schedule to your solar profile and reduce Eskom bills, demand charges and the need for expensive battery storage. Solar PV pumping also works well for moving water from boreholes, rivers or canals to on-farm storage.
The heavy lifting happens when the sun is up. Then, when energy is more expensive or loadshedding hits, you’re only pumping the lighter loads from storage to your irrigation system.
It works like this: a solar PV array is sized to match your pump’s kW rating and connected to a solar-compatible VSD. The VSD converts DC power from the panels into variable-frequency AC for your pump. As the sun strengthens, the VSD ramps up speed. When clouds roll in, it ramps down – but keeps pumping as long as there’s enough light.
No batteries. No hybrid inverter systems. The VSD handles solar input directly in real time.
On cloudy days, you can oversize your PV array slightly to keep the pump running under partial sun, add a backup Eskom or diesel input to the VSD, or simply schedule pumping for bright days.
Many farmers find they can do most of their pumping when the sun is out and rely on stored water to cover the gaps. Some treat solar pumping as a bonus: pump more when the sun shines, hold back when it’s cloudy.
It doesn’t suit every crop or soil type, but for maize, lucerne, pasture and even orchard micro-jet irrigation, it can work well.
Solar pairs best with submersible or vertical turbine pumps that can handle variable speed and flow. The key is to make sure the system doesn’t deadhead or cavitate when running at low speeds. If you’re replacing diesel pumps, you might need to rethink your design head, pipe diameters or pressure needs. But if you’re building from scratch, you can optimise everything for solar.
At Decentral Energy, we design and deliver off-grid energy systems that work for real farms. From solar-direct pumping for pivots and storage dams, to hybrid systems with batteries or backup generators, we work with producers, irrigation experts and agronomists to deliver water where and when it’s needed – without the diesel bills or Eskom fixed connection fees. If your system needs upgrades to work better with solar – like switching to more efficient pumps, resizing pipes, or adding basic automation – we can take care of it. In many cases, we can wrap these upgrades into a single finance package, paid off over time from the savings on diesel or Eskom.
If you’re thinking about upgrading your irrigation or water pumping with solar PV, and want real-world advice, get in touch.
