climate change energy food

What is agrivoltaic farming?

Agrivoltaics is a word we might hear more often in the coming years. It refers to using land for solar power and farming at the same time, which is something I’ve written about a couple of times without using that specific term.

For example, this week a substantial new solar farm was given the green light in Leicestershire. (It’s outside the village of Quorn on a street named Flesh Hovel Way, and I know this sounds like I’m making it up.) It got permission because it isn’t permanent – it will be there for 40 years and then the land will be restored. And secondly, cattle will graze between the solar panels throughout, so it will remain agriculturally productive.

This is the low end of combining solar and farming, and other options include raising chickens or pigs under the panels, or planting wildflowers and hosting bee-hives. This double-use of the land increases renewable energy without reducing food security, and that’s important. It’s also a big advantage to farmers, and it could revolutionise the fortunes of some rural communities.

Where it gets more interesting, and where the word agrivoltaics really comes into its own, is when farming techniques specifically tap into the benefits of the solar panels. It’s only as the number of solar farms expanded that these opportunities were identified, and then studied, and are now being replicated. First developed in Japan and China, the term agrivoltaics was coined in 2011 to highlight the way that solar farms were discovering new ways to raise crops, making use of the shaded micro-climate that is created under the panels.

Projects in Algeria and Morrocco have recorded higher potato yields when grown under the panels. It keeps the heat off the plants and prevents the soil from drying out. You can also run irrigation and even desalination off the solar if you need it, with energy needs met on site. Farmers in Germany have discovered that plants that traditionally grow in woodland, such as raspberries or blueberries, thrive under solar panels.

As it reduces evaporation and protects plants from scorching sun, agrovoltaics might play an important double role in a changing world – generating clean power and helping farmers to adapt to more challenging conditions. At its most ambitious, farming under solar panels is reversing desertifcation and restoring depleted agricultural land, as I’ve described before in China.

Since agrivoltaics is relatively new, innovative applications are still being developed. The German firm Franuhofer ISE has examples of solar on elevated gantries high enough to drive a combine harvester underneath. Or used in orchards, or solar canopies covering shrimp ponds in Thailand. A vineyard in China has been experimenting with PV overhead. There is a lot of interest in Japan and South Korea, where land is limited and solar farms struggle to get permission if they reduce agricultural production.

Looking to the future, emerging ideas include transluscent panels tinted different colours according to the preference of the plants beneath. Another team of researchers, this time in Saudi Arabia, are developing a system that creates water from the air to irrigate plants. A hydrogel fitted under the solar panel absorbs moisture from the ambient air overnight. When the panel heats up during the day, it pushes the moisture out of the gel and it drips onto the plants. This is all done with the waste heat from the panels, leaving the PV itself to generate electricity.

Bear all of this in mind the next time you hear someone grumble that solar panels are taking up farming land. Yes, that happens – but it doesn’t have to. It’s not an either/or, and farmers that choose to do both are going to reap the rewards.

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