A Waikato farm consultant says sheep farming under solar panels can be complementary and profitable.
There are, however, conditions to its success, Total Ag’s Rob McNabb said.
McNabb was involved in the consenting process of some of the proposed solar farms being installed around Waikato.
That process included showing a farm system on behalf of the applicants that can be presented to local government as part of the farm’s consenting application.
He presented the system at a Beef + Lamb New Zealand field day on Lance and Robyn Kerr’s beef finishing farm in north Waikato. The Kerrs are building two solar farms on their property – a 6 hectare private farm and a110ha venture with Island Green Power.
McNabb calls the system “agrivoltaics”, the integration of livestock production with solar energy.
“The whole aim of this is to increase the profitability of the land while maintaining the productive capability,” he said.
The height of the solar panels dictates what kind of livestock can be farmed under them. The cost of elevating the panels to a height that would allow cattle to be farmed underneath is horrendous and most are designed to be no higher than around 800mm.
This limits options to sheep or goats, he said.
There are also other considerations. Soil temperatures under solar panels are generally lower, which for regions such as northern Waikato is a bonus. Light penetration under the panels also limits pasture growth.
Animal welfare considerations also dictate farm system options.
On a farm like the Kerrs’, where there is no woolshed or sheep yards, infrastructure has to be considered.
One of the biggest benefits of farming under solar panels is shading. A Canterbury study showed that woolly ewes produced more and spent 54% of their time under solar panels.
“A lamb will eat 18% more if you give it shade.”
“Any time we can give our animals and opportunity to operate at a lower temperature, we tend to get more production out of them.”
Water usage is less and solar panels in drier climates produce more forage than they do when exposed to the sun.
There is also potentially an increase in clover yield if the land is not fully shaded because of soil and ambient air temperatures, he said.
In the case of the Kerrs’ 6ha farm, Oakridge Solar, challenges included constrained shepherding during lambing because of visibility issues, matching feed demand with supply in late spring-summer and infrastructure requirements.
McNabb’s model for the Kerrs’ 110ha farm sees ewes with lambs at foot bought in during October-November, thus eliminating lambing on the farm and any potential welfare issues.
Additional lambs are also purchased in November-December and those ewes bought in with their lambs will be culled in December.
The lambs are traded over summer and carried over through winter. The winter lamb stocking rate is around 9 per hectare, he said.
McNabb acknowledged that it requires a good relationship with the meat processor to have ewes culled in December.
“It’s about forward planning,” he said.
The net figure off 110ha will be around $1778 a hectare.
McNabb said it will require infrastructure investment into yards, a drenching race, shearing, fencing and water.
There are solutions to reduce the costs, including portable yards and shearing systems. As well as infrastructure considerations, it also requires a high level of sheep farming skills.
Solar farming and sheep and goat production will have to go hand in hand because of the maintenance costs if the grass is not grazed.
The alternative is mowing, which risks dirtying the solar panels and means they would have to be more frequently cleaned.
Solar farming and sheep and goat production will have to go hand in hand because of the maintenance costs if the grass is not grazed.
The alternative is mowing, which risks dirtying the solar panels and means they have to be cleaned more frequently, he said.
