The farm Taaiboschdraai is situated on the Orange River, 29 kilometres downstream of the Vanderkloof Dam. It is farmed by Reghoek Boerdery, owned by the Badenhorst family — Gerhard, Kasper, and Corrie.
The Vanderkloof Dam, with a surface area of 13 874 hectares, a volume of 3 236 million cubic metres, and a height of 108 metres (the tallest in South Africa), is one of only eight dams in the country with hydro-electric generation capacity. The dam operates two turbines with a combined output of 240 megawatts at a release rate of 400 cubic metres per second. These impressive figures are important because the release of water — either for electricity generation or to manage excess storage — can raise water levels near the farm’s pump stations rapidly. At full capacity, the dam can release up to 8 500 cubic metres per second through its sluices.
Faced with the need to irrigate 120 hectares of maturing pecan orchards, in addition to three pivots covering a further 120 hectares, the farm also had to contend with fluctuating river levels and rising electricity costs. To meet these challenges, a new solution was required.
Increase water supply, reduce energy
In 2022, SAW Africa was commissioned to design and implement a system that would increase water supply to the orchards while reducing energy use. This built on an earlier project completed in 2013, when SAW Africa had installed an auto-levelling float and submersible pumps to irrigate three 40-hectare pivots. However, the original system could no longer keep up with the trees’ growing water requirements.
After a full investigation, the design was upgraded. Two new Grundfos end-suction pumps were fitted to the float as low-lift pumps, increasing pumping capacity from 650 m³/h for the pivots to an additional 650 m³/h for the trees. The float continued to manage changing river levels, while minor structural modifications allowed for the removal of the old submersible pumps and the installation of the new equipment. Onshore, two additional Grundfos end-suction booster pumps with higher head capacity were installed. By placing the high-head pumps on land, the floating pumps could remain smaller and easier to manage. Identical pump and motor sets were chosen for both applications, ensuring interchangeability and redundancy through standardised manifolds and pump designs.
New pipeline
The old pipeline supplying the orchards was undersized and could not meet the demand of mature trees. As water flow increased, so too did the pressure requirements, driving up energy use to 159.2 kW. A new, properly sized pipeline was installed to divide the flow into two branches, reducing the system’s pressure demand and cutting energy use significantly. This redesign resulted in a saving of 61.25 kWh.
The 39% reduction in energy use not only lowered electricity consumption but also reduced the number of solar panels required to power the system, substantially lowering capital costs. By building a smaller solar plant, the farm saved R2 425 854.00 — an amount that more than offset the R734 550.00 spent on the new pipeline.
At a levelised cost of R2.18 per kWh in 2024, the monthly saving is R32 047.00 based on eight hours of daily operation. The pipeline investment can therefore be paid back in just 23 months, after which it will continue to deliver annual savings of 61.25 kWh. Over 20 years, this amounts to an impressive R7.7 million.
SAW Africa, which designs and manufactures single-axis solar trackers locally in Kimberley, South Africa — “designed in Africa for Africa” — supplied solar trackers for the project. These increased solar generation hours by four hours per day, a 38% improvement over static panels. In summer, the system can now deliver up to 11 hours of solar energy daily, dramatically reducing reliance on grid power.
The solar energy is delivered to the pumps through SAW Africa’s VSDs and switchgear, equipped with solar-input capability, maximum power point tracking, and a pressure management system. The system can operate either off-grid or in a hybrid mode, blending solar and grid power during the night or low-light conditions. Importantly, this configuration does not require licensing from NERSA or Eskom — only notification — provided it complies with all relevant SANS and NRS standards. The system can never feed power back into the grid.
Operating 19 hours a day for at least 225 days a year, the system reliably meets all irrigation needs. Given the low average rainfall of only 225 mm per year in the region, rainwater was excluded from the design considerations.
Savings of over R2m
The cost of solar power for this system, including interest at 12%, is calculated at R1.57 per kWh over a 10-year payback period. This rate is fixed, as the farm owns the system outright. After the payback period, electricity is essentially “free”, apart from annual maintenance costs of R57 000.00. The warranty can be extended to 10 years through a service plan, covering the solar trackers, panels, VSDs, switchgear, motors, and pumps.
With a projected lifespan of over 40 years, the system can also be upgraded in future to operate entirely on solar power.
In conclusion, the integration of solar tracking, upgraded pipelines, and efficient pumping technology saved the farm R2 425 854.00 upfront by avoiding the need for a larger solar system, and delivers annual savings of R862 438.00. Over 10 years, with electricity tariffs rising by 10% annually, total savings are projected at R11 711 452.00.
Reflecting on the project, farmer Kasper Badenhorst commented:
“Dit is vir ons as boere bemoedigend dat daar nog ervare en innoverende besighede daar buite is wat unieke oplossings kan vind in vandag se uitdagende landbousektor.”
“It is encouraging for us as farmers that there are still experienced and innovative businesses out there that can find unique solutions in today’s challenging agricultural sector.”
Properly integrated solar systems can help farms remain both sustainable and profitable in the face of rising energy costs and increasing agricultural demands.
*Hannes van Niekerk is CEO of SAW Africa.
