Solar farms put cow comfort and crop yield ahead of harvesting electrons

Solar arrays that promise to generate happier, healthier cows and crops, while producing cheap electrons on the side, are being deployed in France, following a series of government-led energy tenders with a difference.

Spanish energy giant Iberdrola has been awarded contracts to develop four solar projects with a modest capacity of 3 megawatts (MW) each, but what is interesting about these projects is that the primary focus is not on output, but on the benefits that solar panels can provide. deliver to agricultural productivity.

To really drive home this focus, the French government used contracts for difference where the price per MWh was set above market value for 20 years to compensate for prioritizing agriculture and livestock over maximum solar production.

In the first project, called Kirch, Iberdrola will mount solar panels 1.5 m above the ground to shelter dairy cattle underneath.

The panels will also collect and store rainwater. Predictive software will then either activate irrigation systems when needed, or use data from smart collars worn by cows to start ‘foggers’ to cool the animals on extremely hot days.

The other three projects, Maubec, Lapenche and Solomiac, will focus on crops and maximizing land productivity.

Tracker technology normally used to turn panels towards the sun will instead be used for shading, protecting crops from frost in winter and intense sunlight in summer. The panels will be installed in rows from north to south at an angle between -70° and +70° and informed by ground sensors.

Iberdrola says the panels will be installed far enough apart to allow tractors between them.

Cattle and solar energy do not mix

Iberdrola’s innovation will be to find a way to successfully make crop rotation economically viable at its three agricultural projects and for solar panels to work with cattle – large animals that love a good scratching post.

In Australia, cattle-plus-solar has not been nearly as popular as sheep-plus-solar, a trend Wyngery director Ben Wynn says comes down to the added cost of mounting the panels higher off the ground in paddocks with cows to assemble.

“We’ve built a 60 kilowatt prototype at Farrer Memorial Agricultural High in Tamworth which is an amazing piece of engineering, it works perfectly … but compared to a ground-based detection system you’re looking at a cost of about 160 per cent more ,” he told RenewEconomy.

“I think I can get it up to 80 percent, but it’s still high. Developers in this country will choose one form of infrastructure over another because it is one point of a percent cheaper in CAPEX rather than 80 percent more expensive.”

A 1P detection system uses one panel about 2 meters off the ground, about 6-8 meters apart, giving very little access to other users at noon when the panel is effectively horizontal.

A 2P tracking system uses two panels that are 2.2-2.4 meters off the ground and 12 meters in between, providing enough access to even reseed pasture in between.

“While 2P costs 2-4c per watt more to install, our modeling shows that you can offer the farmer a reduced rental rate and then also shift the vegetation management to them, so you don’t have to mow or spray and they look after the fences. You remove ongoing OPEX costs so ongoing IRR goes up 2-3 percent,” says Wynn.

Studies show it works for sheep and horticulture

The emerging combination of complementary solar and farming practices has been dubbed ‘agrisolar’, as both industries seek to make land work double time and mitigate growing complaints about the transition from “prime farmland” to solar farms.

Government-funded AgriSolar Clearinghouse in the US estimates that about 3 million hectares of land will be under solar power by 2030, or 0.33 percent of total agricultural land, while the Clean Energy Council estimates 0.027 percent of Australia’s current agricultural land.

“The combination of farming and solar power in agrivoltaics offers a powerful way forward, increasing social license for renewable energy developments and allowing continued agricultural use of productive land,” farmer and renewable energy proponent Karin Stark said in the report last year Farm Powered written.

Stark says the likes of Japan, Denmark and Germany have been seeding “agrivoltaics” for years, which offer benefits such as higher soil moisture, reduced exposure to extreme weather and better ambient temperatures.

Agrisolar installations include ground-level and mounted solar panels, greenhouses and rooftop panels, and even floating solar used in combination with aquaculture, according to a paper by the Clean Energy Council in 2021.

American studies have shown better yields or more efficient water use for tomatoes, broccoli, chard and jalapenos for ground-mounted solar.

Crops like wheat can be grown under raised solar panels, but one US study showed that it is not cost-effective to rotate them, so permanent plants such as berries or nut trees are more viable.

Solar grazing is very popular in the US and Europe, and the first project in Australia started in 2015 at the Royalla Solar Farm. By 2020, there were 13 known large-scale solar farms grazing sheep in the country, mainly in NSW but also in Victoria and Queensland.

For solar farm operators, the pairing provides free mowing and organic vegetation management, provides extra monitoring when farmers are on site regularly, and strengthens relationships with neighboring landowners. For farmers, sheep grazing on solar farms provide soil with protection from the elements, lower water consumption by livestock, and mushroom beds with secure fences against predators.

Rachel Williamson is a science and business journalist focusing on climate change-related health and environmental issues.