Agrivoltaics
Combining agriculture with solar power
“What we shouldn't be doing is putting solar panels on productive agricultural land”.
Those were the words of the British Prime Minister Liz Truss in a recent interview with the BBC. With global food prices soaring, and serious concerns about local food shortages, no-one wants to remove large amounts of prime agricultural land from circulation by covering it with solar panels.
Fortunately, that is not happening to any great extent. Most solar panels are installed on rooftops, contaminated land, brownfield sites, scrubland, deserts or marginal farmland that can, at best, be used for grazing. Moreover, it is estimated that even if the world were to get all of its energy from solar power, the panels required would take up just 0.3% of Earth’s land area, compared with the 38% used for agriculture.
At a global level, competition between solar farms and agriculture is therefore a relatively small problem, but on a densely populated island like Britain, for example, there is genuinely some conflict. Flat or south-sloping land is attractive to both agriculture and solar farms, and even if the potential loss of food production is small in a global context, it may have a noticeable impact on national food security and local jobs.
In a somewhat parallel situation, in Taiwan some farmers found that renting their fields to solar developers was more lucrative than growing crops. While the solar power industry claimed there was plenty of disused agricultural land available, new rules were introduced which mean that solar farms can now only occupy land designated as agricultural if they can be installed without much loss of agricultural yield. In practice, this means solar panels must either be installed on land that is significantly degraded or they must be spaced out to let sun through so that agriculture can continue. This coexistence of photovoltaic panels with agriculture is known as agrivoltaics.
Origins of Agrivoltaics
The concept of agrivoltaics isn’t new: it was proposed by Adolf Goetzberger and Armin Zastrow in 1981 as a way of increasing the overall productivity of the land, while reducing potential land use conflicts between solar power and farming. It exploited the fact that plants are often not able to use all of the available solar energy, so the excess can be used to produce electricity. Although the idea dates back to the 1980s, it was first put into practice in Japan in 2004, and the term “agrivoltaic“ was coined in 2011.
Agrivoltaics often refers to projects that are primarily agricultural, and secondarily produce solar energy, creating synergies between the two. I will look at some at some projects that meet that definition, but also at some where the main objective is generating solar power, with agriculture being only a secondary objective.
Modern Agrivoltaics
These days, agrivoltaics is about more than just making use of excess solar energy. Africa’s first such project, at Insinya in Kenya, is a prime example of this. The region’s strong sun, high temperatures and low rainfall mean that installing solar panels actually improves agricultural productivity, because the shade they offer reduces heat stress and water loss. This aspect of agrivoltaics will only become more important in the face of global heating and droughts exacerbated by climate change.
Developed in cooperation with the University of Sheffield, the project focuses on creating benefits for the local community. As well as improving agricultural yields, the solar panels ensure access to affordable electricity and help to harvest rainwater. The hope is that the shade provided by solar panels may even enable horticulture in places where it is not currently possible. This emphasis on protecting crops from excessive heat and sun, in tandem with supporting local communities and boosting the rural economy, is also highly relevant to places like India.
Like Kenya, Spain is a country blessed with abundant sun, but where the summer heat can be excessive for many crops. Recently, a number of agrivoltaic projects have been completed, including the Winesolar pilot project in the province of Toledo. As the name suggests, vines grow beneath the solar farm, and the project is using artificial intelligence to optimise the angle of the panels to protect the vines from excessive sun and rain. This should improve the quality of the grapes, and if the pilot is successful it will be rolled out to more locations.
Also in Spain, but this time in Extremadura, the El Doblón solar farm hopes to grow grapes for making cava. In the meantime, sheep graze beneath the panels, enjoying the shade afforded from the region’s famously fierce sun. Other solar farms in the area are combining electricity generation with growing broccoli and herbs, as well as with beehives. One farm is also installing nesting boxes for birds like falcons and owls, to minimise the impact on the local fauna.
In countries further from the Equator, there is less benefit to be had from protecting your crops from the sun, but agrivoltaics can still increase the overall economic productivity of the land. In New Zealand, the aim is to maintain 85% of the original farming yield at the same time as generating energy. This is similar to the Taiwanese model and should be a useful reference point for countries in northern Europe.
Exciting Prospects
Large-scale agrivoltaics is in its infancy, and the best ways to combine energy production with agriculture are still being explored. For example, in Germany they are trialing vertically mounted bifacial panels, which generate electricity on both sides. If installed with the cells facing east and west, they generate most power in the morning and evening – rather than at midday – coinciding better with peak demand. That increases the value of the electricity produced and reduces the need for energy storage. What’s more, panels installed vertically may even generate more electricity overall than they would in more traditional configurations. Another advantage of vertical panels for agrivoltaics is that you don’t need to raise them above your crops or animals, which can simply grow or graze between them.
For the moment, agrivoltaic projects only generate a very small proportion of the world’s electricity, but there are promising signs that it is becoming an increasingly important niche. It can be of particular benefit in places with hot and dry climates, by improving yields and allowing new crops to be grown. It also has great potential in densely populated areas with competing needs for food and energy. And in poorer countries it can act as a catalyst for development, by providing access to energy in rural areas. These wider benefits to society may prove to be just as important as the ability of agrivoltaics to increase the economic value of agricultural land.