Solar power saves irrigation costs


By Digital team | 14 August 2017
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Green gold. Dewald in the lucerne lands that are irrigated by the moveable, solar-powered centre pivots. The lucerne which they don’t utilize themselves is baled and sold to other farmers.

Each rotation of the centre pivots driven by solar power on this farm means money back in these farmers’ pockets. After nearly four years of using the system, they’re still singing its praises.

For father and son team, Joppie (53) and Dewald (25) Opperman of the farm Hazeldene near Cradock in the Eastern Cape province of South Africa, the use of solar energy for irrigation took on a whole new meaning after they requested a quotation from the company, All Power, in Port Elizabeth a few years ago. They were looking for a solar-powered system that would be capable of providing sufficient energy for a centre pivot to cover an area of 10ha.

Joppie, who started farming in 1984 and had a good knowledge of flood irrigation, says that due to limited water resources on the farm (borehole, springs and earth dams), he acquired his first centre pivot in 2008 to utilize the available water supply more efficiently.

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The Oppermans – Joppie, Dewald and Chrismariè – on their farm Hazeldene near Cradock.

Although there had been electricity supply from the national electriticy provider in South Africa – Eskom – on the farm since 1992, it was cheaper at that time to use a Deutz three-cylinder diesel motor to drive the centre pivot because of the distance from the supply point to the lands.

When the price of diesel rose to more than US$0.67/litre in 2011, they approached Eskom for a quote to install a 2km-long line to the lands. Without the cost of electricity supply points, the quote came to US$17 200. This was double the cost of the Opperman’s first centre pivot.

It was then that an agent at Cradock recommended that they pay a visit to All Power in Port Elizabeth to find out if the centre pivot could be powered by solar energy. This company has been providing solar-powered systems for livestock and game watering points out on the veld throughout South Africa since the 1980’s.

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The 64-panel solar-powered system at Hazeldene that powers two centre pivots that in turn provide 50 000 litres of water per hour to 13ha. The total cost to establish this system, including pumps and cables, was around US$26 000.

Joppie recalls their first meeting with Terry Moss, owner of All Power. “Terry’s first words were: ‘I will develop a system that will work, and if it doesn’t, I’ll give you your money back!’.” After a visit to Hazeldene, Terry quoted the Opperman’s US$21 300 for the installation of a 48-panel solar power system with an immersion pump and cables.

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Terry Moss, owner of All Power, knows the needs and requirements of farmers since he is also a farmer. Terry is also coincidentally a former South African motor racing champion.

Joppie asked Terry to give him some time to do his own calculations. “With the cost of diesel amounting to US$375 a month, the capital expenditure of laying an Eskom line to the lands and then the cost of electricity supply points and monthly electricity costs, it made sense to consider All Power’s quote, even if it meant taking out a loan from a bank.”

Because it was also a first for All Power, Terry offered to loan Joppie the purchase price and let him pay it back over four months. “I told Terry that he must remember that us Karoo farmers have to watch our money carefully. The fact that he offered to give me my money back if the system didn’t work eventually won me over,” recalls Joppie.

The Oppermans erected the frame themselves and the system was completed within a week. “It was coincidently cloudy on the day we turned on the system. However, when the centre pivot started working within a few minutes we instinctively knew that we’d made the right decision,” says Joppie.

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An excellent maize harvest at Hazeldene. The Oppermans expect a yield of more than 16 tons/ha from their lands under solar-powered centre pivot irrigation.

With the exception of the days when there are thunderstorms and dark, thick clouds covering the sun, the solar panels supply sufficient power to drive the system, even on partly cloudy days. “In any case, there is a correlation between a crop’s water needs and the sunshine. If it is cloudy, or it rains for a couple of days, then the plants have a reduced water requirement and vice versa,” says Dewald.

In the mid-summer, water can be pumped from 07:00 to 18:00. If it is cloudy, the output is reduced by an hour a day. In winter, the system delivers power from 08:00 to 16:00.

NORTH-FACING

It is nevertheless extremely important for the solar panels to be facing true north. Although the water-powered centre pivot only drips for about 15 minutes as the sun starts to shine (when the pressure is less than 100kPa), it gets going as soon as the pressure reaches 200kPa. The same applies in the afternoon as the sun begins to set.

All Power also offers a patented option in which the solar-powered modular frame can be seasonally adjusted to ensure optimal power supply throughout the year.

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All Power offers a patented option in which the solar-powered modular frame can be seasonally adjusted in order to deliver an optimal power supply.

BATTERY-FREE

The system which the company set up at Hazelene works without batteries. A bank of batteries can be added at an additional cost should the farmer wish to extend his irrigation period. Because the Oppermans acquired an electrical two-tower centre pivot (9ha) two years ago that runs alternately with a diesel motor and solar power, they decided to expand the solar-powered system.

They added another 16 solar panels at a cost of US$4 640. This gave them additional pump hours at a total output of 50 000 litres an hour for the entire system.

Dewald says that if one already has Eskom power or diesel motors on lands under irrigation, this system can be used as a back-up or for night irrigation.

SERVICE DELIVERY

After almost four years of using the solar-powered system, the family highly recommends it. They say that the most important factor is to ensure right from the start that it is sourced from a reliable service provider.

“These days there are various suppliers of this type of system. The few times that I have contacted Terry about small problems, he has come out immediately to the farm or sent someone here. In addition, as he’s expanded his knowledge, he’s come and upgraded our system free of charge,” says Dewald.

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A view of the farm Hazeldene near Cradock in the Eastern Cape province of South Africa, where solar-powered centre pivots are being utilised.

CAPITAL EXPENDITURE

Although the Oppermans originally calculated that it would take about five years to recoup their capital costs of the solar-powered irrigation system, their calculations now show that it is possible to do so within four years, once the price of diesel and Eskom tariffs have been taken into consideration.

“Because the solar panels come with a 25-year guarantee, we have the peace of mind that we made the right decision. We are considering the possibility of expanding the system by pumping the available water to a reservoir that will be situated at a higher elevation, which will then drive the centre pivots with gravity.

“The cost of the system – roughly US$2 020/ha – was worth every cent,” the Oppermans say.

ENQUIRIES: Dewald Opperman, email: Dewald.hazeldene@gmail.com