Achieving the Impossible with Solar Power

August 2020

One of the best things about Think Water is their ability to draw upon innovation and deliver solutions for the impossible. It was through the use of solar power that Think Water Gisborne achieved the impossible with a solar pumping station for Pamu Farms in Rere.

Winner of the 2020 Think Water Project of the Year

Pamu Farms contacted Think Water Gisborne with a challenging need to pump 60,000L/day of water 250 m up the hill from a creek to a series of storage tanks for the purpose of stock water.

The project had been rejected by two competing business before Think Water Gisborne accepted it. So, with many challenges the team got on with the job and started the design process.

The main challenge was the need for a custom designed solar-powered system to suit the existing wet end. An off the shelf solution doesn’t exist.

A HydraCell pump was chosen for its ability to pump abrasive materials (such as pumice) present in the water, low service requirements and the ability to pump high head (250 m). The design required a solution that supplied a large amount of torque to get the pump turning over without using an excessive amount of solar panels. While also slowing down to 630 RPM to suit the flow and pressure limitations of the existing hydra-cell wet end pipework, which was capable of producing 850 m pressure.

The decision was made to partner with Weg/TRind NZ who assisted with the design and commissioning phases of the project. Weg/TRind NZ supplied a 10-pole motor and CFW500 variable speed drive with a solar module. This allowed us to independently control the torque by utilising the Voltage Vector Weg (VVW) regardless of the speed, allowing the pump to start on a higher torque by converting voltage to torque.

Remote site location was another challenge. Situated two hours’ drive from Gisborne, with the last 45 minutes of the journey across rough uneven terrain. This proved to be a challenge in getting product and equipment to the site. We had originally planned to fly everything to site but we managed to strike it lucky with the weather and some recent farm track maintenance being done.

Solar Pumping Station

To assist with commissioning a remote management system from Halo was installed. This allowed the team to keep an eye on the system and show up prepared with an understanding if the changes that needed to me made to get the most out of the system.

The Halo system facilitates monitoring of volt, current, and hertz data via a live feed through cloud-based software that can be accessed and programmed from any device with internet access. This allowed us to see how the solar pumping station reacted to the drive settings, and give the farmer the ability to see tank level flow and weather amongst other features.

The complete installation took place over three weeks with the use of an excavator and a lot of hard work. Think Water Gisborne is proud to say they performed what was considered impossible by other companies and delivered the project with great success.