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Off-grid farm reduces energy costs

22 June 2023

An off-grid livestock farm has eliminated its use of a costly and inefficient diesel generator water pumping system by implementing a solar-powered solution controlled with variable frequency drives (VFDs), reports Owain Betts

FARM CAMARATUBA in Piaui, Brazil, is located in a semi-arid region, posing a challenge in producing livestock fodder. As a result, a large quantity of fodder needs to be transported to the farm, while water also needs to be pumped to different areas of it for irrigation and livestock.

A 150KVA diesel generator was used to pump water from a 150ft deep tubular well into an irrigation system feeding 17 hectares of land. Additionally, there was no control over the amount of water being pumped from the well when the system was active, resulting in wasted water.

The farm’s owners worked with WM Engenharia on the project. They designed and installed the complete system which consisted of 15 photo-voltaic panels on a six-string system using an Invertek Drives Optidrive P2 Solar VFD which controlled the pump. A second drive will be used for a future pumping system using a PV system.

Marcus Silva, head of sales at Invertek Drives Latin America, said the farm faced several challenges during dry periods: “It struggled to produce sufficient fodder for its livestock without relying heavily on irrigation or transporting it in from a supplier.

“Additionally, the farm was not linked to the main electric grid and had to rely on a diesel generator for the pumping, thereby incurring significant expenses in transporting fodder and running the generator.

“However, with the introduction of a photovoltaic-powered pumping system, the farm was able to eliminate the need for the generator and irrigate larger areas of land when it needed to and with the necessary quantity of water.

“Consequently, they were able to produce their own fodder reserves with a higher nutritional value throughout the year, thereby mitigating the costs of transportation and diesel consumption; as well as the emissions created by the generator.”

He added: “Another advantage was the ability to control the amount of water being pumped. Previously, it was a case of switching the pump on and a constant flow was fed into the irrigation system. The VFDs allow the flow and quantity to be altered depending on the amount required, preventing wasted water.”

The diesel generator was replaced with a 47.7kW photovoltaic system to power the existing 35HP submersible pump installed in the well.

Two Optidrive P2 Solar VFDs (380V, 50HP, IP20 enclosure rated) were installed, one to control the system and another will act as a reserve for the installation of a future pump.

The P2 Solar Pump VFD is available with an extended DC operative voltage range of 345-800Vdc and 185-410Vdc. It is designed specifically for applications involving watering, irrigation, agriculture, swimming pools, water supplies, water treatment and others where solar energy can be harnessed.

Quite often these are in hard-to-reach or off-grid locations. However, many are also in commercial or residential areas where the advantages of Solar / PV technology can be used for environmental or cost reasons.

The P2 Solar is available in IP20, IP55, and IP66 / NEMA 4X enclosures, making them suitable for all environments and conditions.

The range includes 0.75kW to 250kW, 1HP to 350HP. It includes extended DC operative voltage range, 345 to 800Vdc HV, 185 to 410Vdc LV which increases the system operational time per day and reduces unnecessary stoppages caused by the low array voltages during dawn and dusk.

Owain Betts is PR and communications manager at Invertek Drives


Key Points

  • A photovoltaic-powered pumping system has enabled an off-grid farm to eliminate the need for a generator 
  • The 15 photo-voltaic panels on a six-string system use an Invertek Drives Optidrive P2 Solar VFD to control the pump
  • The VFDs allow the flow and quantity to be altered depending on the amount required, preventing wasted water