Solar Powered Water Reticulation

The use of solar panels to provide power for pumps in remote or awkward locations is proving economic for irrigation and is improving water supply, subdivision and grazing management.

In 2017 the Ministry for Primary Industries published a report on the pros and cons of installing stock water reticulation systems on hill country farms throughout New Zealand. The benefits they identified included; an increase in stock units per hectare, increased animal productivity, better grazing management, greater pasture production, better environmental outcomes, greater ability to implement farm environment plans and increased drought resistance. Financial analysis showed an average rate of return of 45% over 20 years with an average payback period of 3 years.

Three years on from this study, there have been quite a number of successful applications of this technology and for both stock water and crop irrigation around the country. 

Off-grid solar powered water reticulation on a sheep and beef farm:

Ben Ensor farms Jedburgh, a sheep and beef breeding and finishing operation, carrying 12,000 stock units. The 1400 ha dry hill country property is situated to the east of Cheviot in North Canterbury and runs to the coast just north of Gore Bay. This land rises from zero to 440m above sea level. Another 120 ha of irrigated flat land at Spotswood supports the main farm. 

Ben explains the original water was through a County scheme developed in the 1960s, that had few troughs and many small pipes that struggled to meet present day stock requirements. The property was largely dependent on natural water stored in small dams, but it wasn’t high quality, and was often unreliable throughout the summer dry period. There was a need for a better system to support stock management. 

They went through the farm, replacing the pipes and installing more troughs. An alternative spring-fed water source was identified but it was situated at the bottom of a gulley, on the coast, close to sea level and a long way from any power source. The research began. Ben says, “we were talking quite a big lift, and quite a volume of water”. They looked at the cost to deliver mains power to the water source but it was prohibitive, then spoke with Frizzell Agricultural Electronics to find another solution.

Nick Frizzell, technical manager for Frizzell Agricultural Electronics, explains that a solar array was constructed to power a 10-kilowatt pump that brings water from the water source to a storage tank 240 vertical metres above and about 2km away. In the evening the storage tanks supply gravity-fed water to the troughs. During the day, the pump brings water up to the storage tank to keep the reservoir filled.

Panels that can produce about 15 kilowatts of power were installed, as Nick says, on an overcast day, there will still be enough energy to drive the pump. While this system and the one at Gareth Cox’s are off-grid, in some situations, farmers are able to take advantage of grid tie set ups to enable an optimum combination of mains and solar power arrangements. Nick says “Solar panels are becoming more efficient and therefore more economic. They are also scalable, if a farmer wanted to drive a larger pump, they could use the existing panels and add more to build the required amount of power.”

The cost of any system depends mainly on the number of stock and therefore the volume of water required along with the vertical lift needed. Nick says that solar power for irrigation systems is now becoming more economic with new and more efficient solar technology. “Getting power to a remote centre or corner pivot means power lines, cables and a transformer and can be prohibitively expensive whereas solar systems are more economic,” says Nick. “A well-designed system used correctly will have a relatively fast payback period and it can be years before any maintenance is required.”

Ben says from his perspective there are multiple benefits with the system. There are better environmental outcomes, as stock stay out of dams and other water sources when, combined with smart subdivision, they have a ready access to good quality drinking water. Animal health and production is improved because stock is well hydrated and, with better control and of pasture management and stock movements, they are better fed. As well and very importantly, Ben cites the peace of mind he gets as a farmer with the knowledge that his stock is as well looked after as possible.

Portable solar powered irrigator on a cropping farm:

Gareth Cox of Riverbank Farming produces a variety of crops on his mid-Canterbury property including peas and rye grass for seed, and barley. He uses a solar powered irrigator over three corner sites of about 3ha each. Being solar powered, the system is highly portable. The 113m pivot irrigator is relocated between sites by tractor. Water is delivered to the site and the solar power drives the pivot. 

Gareth says the system works well with the lower water pressure he has on the property and while the installation cost was about $11,000, there are no ongoing maintenance or power costs, until the battery eventually needs replacing, “but hopefully we’re a wee way from that.” Nick estimates a battery lasts around 10 years and costs about $3,000. The estimate for bringing power to this site was in the region of $30,000, excluding the cost of power on an ongoing basis.

Nick Frizzell explains that with corner or other awkward sites, farmers often have access to water but not to accessible power, so the option of having a completely portable, stand-alone system is a good solution. 

Nick says the planning for each system depends on the location and its radiance figures (the amount of energy reaching that area from the sun over a year). It also depends on how long the machine is going to be run for, so each system is designed for a particular situation. It’s also designed to be universal between different manufacturers, so it operates like a generator, with a three-phase plug.

Gareth adds that it is an effective way of delivering a small amount of water over the 9ha, and that as he is already paying for the water in a high cost water system, he needs to be sure he is efficiently maximizing the use of the water he has paid for.

MPI - Ministry for Primary Industries

Showdown Productions Ltd – Rural Delivery Series 15 2020