Page 44 - Energize May 2022

TECHNICAL

Solar powered irrigation for

agriculture – SA’s largest private

solar farm

INFORMATION FROM VICTRON ENERGY

180-ha pecan nut orchard in Hartswater, South Africa has Heavy duty bus bar
solved its irrigation problem virtually overnight, by installing Izak Oosthuizen, the managing director of Ecotrades says: “One of
A the region’s largest off-grid low-voltage solar farm. the biggest challenges in this installation was battery balancing.
The problem was not access to water – 1200 km of canals The installation includes 336 batteries – all of which must be
constructed as part of the Vaalharts irrigation scheme supplies connected using identical cable lengths. Potentially there’s going
the water they need. But the electricity grid infrastructure to be a lot of slack cable. In the end we were able to solve the
was unable to cope with demand and was subject to a rolling problem – for which we’d like to acknowledge the help received
schedule of power shutdowns. Even when the supply was on, it from Victron’s sales manager Gerrit Tromp – with an ergonomic
was notoriously unstable. battery arrangement, wired into some really heavy-duty bus bars
This farm waters its orchards in rows according to a timed 100 mm wide and 10 mm thick.”
irrigation schedule – a schedule which is cycled throughout
the plantation. Water has to be ordered in advance from the The system comprises:
irrigation scheme and is channelled to the farm in time slots. If a • 18 Quattro inverter/chargers rated at 15 kVA – totalling 270 kVA
power cut coincides with the water’s arrival, the farm is unable • 50 SmartSolar MPPT charge controllers 250/100 VE.Can
to extract it; the water is lost, money is lost; the irrigation • 12 Fronius Eco 27 kW 3-phase solar inverters
schedule is spoiled, and trees are left in drought conditions, • 336 SolarMD SS 202, 7,4 kWh Lithium batteries – totalling 2,5 MWh
devastating the harvest. • 1680 Longi solar panels rated at 430 Wp – a total of 722 kWp
• 2 Cummins diesel backup generators rated at 200 kVA each
Two systems provide 270 kVA • 9 step-up/ step-down transformers to reduce losses in the 4,5 km
The Hartswater Pecan Plant decided the time had come to make of private grid infrastructure
a major investment in private power – for which they turned to • 2 Cerbo GX control and monitoring units provide system
Ecotrades Solar Power Systems, South African experts in domestic monitoring and control – including control of third-party devices
and industrial solar power. Ecotrades suggested a 270 kVA private • 36 000 BTU air-conditioning keeps the high-power inverters
power supply divided into two separate power infrastructures, to functioning optimally.
avoid voltage drops on the cable distribution network which runs
to 4,5 km. A late enhancement to the planned design was to mount the solar
Ecotrades pre-installed the system in four insulated, air- charge controllers outside the container, where they can readily
conditioned shipping containers – two for the battery banks, two dissipate heat whilst reaping their huge solar harvest. The solar
for the inverters – carrying out the work on their own premises chargers have an IP43 protection rating (unit is protected from water
before transporting the valuable cargo securely to site in their spray falling vertically, or within 60° of vertical) so there was no
own crane-trucks. ‘downside’ to installing them open to the air, under a profile roof.

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