Farming livestock in the shade of solar panel arrays is taking off overseas and offers opportunities in New Zealand. By Delwyn Dickey.
With more solar arrays being deployed in farming areas and more likely in the future, two research projects are looking at different aspects of incorporating the arrays into a working farm.
Solar grazing, where sheep are run under the photovoltaic panels is common overseas, although not universal, with sheep farmers in the United States and Canada having their own solar grazing associations. The sheep are generally run as a separate operation to what is happening on surrounding farmland.
Farm consultant Anna Vaughan with Tambo NZ wondered why the arrays weren’t being used as part of the farming operation instead of as a stand-alone venture.
“Solar panels going on farms seemed to be an either/or situation rather than ‘how could this work for the livestock farms’,” she says.
With decreasing stock numbers to meet greenhouse gas emissions regulations likely, finding ways to increase on-farm revenue is also going to become more of a focus for farmers, Anna says.
To find out how the arrays would stack up financially for a farming operation she contacted Alan Brent – chair in sustainable energy systems at Victoria University of Wellington and along with scientists at Lincoln University, and they applied for funding through the Rural Professional Fund with Our land and Water National Science Challenge.
Alan reckons he is “stoked” to be involved with the study as he sees agrivoltaics as an important opportunity for New Zealand.
The desktop study will look at both a dairy farm and a sheep farm, in Canterbury, as case studies. http://wgtn.ac.nz/sustainable-energy-systems
There will likely be animal welfare gains for livestock as the panels offer good shade, especially for lactating dairy cows, Anna says, with issues around heat stress in stock likely to become more important as the climate continues to warm.
“The aim is to develop a business case for a system on the farm – how much would it cost and what would it look like,” Alan says. “But the project will also be looking at the productivity of the farming itself,” he says.
There are a myriad of things to be considered as far as economics go with the farm being close to a connection point to the national grid probably the key one.
They will be working on the assumption the installation, operation and maintenance of the array would be done by an outside third party rather than by the farmer. High onfarm power use with running dairies and irrigation systems like pivots tends to see dairying operations more likely to benefit from an onfarm solar array, Anna says, although consideration would need to be given to whether you could use pivot irrigators or k-lines with them, she says.
With the panels needing to be raised further
off the ground than is needed for sheep, this also sees bigger installation costs. Although there are solar operations overseas growing crops beneath the panels only a few places have looked into running cattle under an array.
One is a prototype installed at the Farrer Memorial Agricultural High School in Tamworth, New South Wales, which is used to power irrigation at the school.
The 60kW array has panels set at 2.4 metres off the ground with Angus bull yearlings and Illawarra dairy heifers and adult cattle regularly running under them. Ben Wyn owns Wynergy the solar installation company specialising in agrivoltaics in Tamworth that installed the array.
The array is performing well with no issues cropping up from the cattle. The 15-month-old bulls particularly love to scratch on it and give it a real workout, he says.
Despite this the company hasn’t sold or completed any other cattle arrays since this one went in in 2021.
The high cost of installation – an extra 80% compared to one suitable for sheep, may be behind this, he reckons, although with plenty of land and roof space available locally Ben says there seems to be little call for the design.
Higher costs come from the use of more robust materials to withstand the higher winds found at height, the heavier animals rubbing against them, and added construction costs at height.
For his part Ben reckons a smaller 5MW cattle array wouldn’t be economical if it was simply grid connected and earning a low power purchase agreement (PPA) rate.
TARANAKI RESEARCH
The effects the panels have on the pasture around and underneath them is behind another year-long project on an existing solar farm in Taranaki.
Aimed at sheep grazing, the research will look at the effects of shade on the pasture to get an idea of carrying capacity under and around arrays.
“Many of the solar farms overseas are installed in areas that have quite dry, arid conditions with very low stocking rates,” Professor Paul Kenyon says. Paul along with Professor Danny Donaghy from Massey’s School of Agriculture and Environment is leading the research, with funding from the Agricultural and Marketing Research and Development Trust (AGMARDT).
As pasture production in NZ is quite different we need to know how much pasture you’ll still grow in any given hectare, which will set stocking rate or carrying capacity, he says.
There is potential for more diverse species to be used around the panels but for this trial, with the Taranaki array set up on standard ryegrass and clover pasture, this is what will be trialled.
“Because of the potential shading from the panels, the composition of the sward is likely to change to potentially less-palatable weed species, which will affect the carrying capacity.
Taking measurements for an entire year will show how the amount of shading and light each area of land receives differs each day and across seasons giving a total picture of pasture production and therefore animal carrying capacity.
In warm environments the shading, which could see warm and moist conditions develop, could potentially lead to increases of facial eczema, he says.
With dairy sheep also showing potential as a lower environmental impact option to dairy cows Paul sees no reason why a dairy flock couldn’t be run under the panels, offering another revenue stream option.
Like Alan Brent, Paul sees a bright future for agrivoltaics in NZ.
“There is a lot of interest in this. Like any new system it’ll just take time to understand how to better manage that system.”
