As climate change continues, summer in East Anglia is beginning to feel like the south of France. This is a challenge for farmers who are seeing significant reductions in crop yields and livestock growth. And although more sunshine means more potential solar energy, there is widespread resistance to putting solar panels on farmland. But, as farmers in mediterranean countries have been finding, there is a solution which can help with both problems. After an unprecedented series of heatwaves we thought it worth republishing an article on this from last year. Clever use of solar panels can improve farming as well as increasing energy independence.
The last decade has seen a dramatic expansion of solar farms in the UK. In our relatively sunny region, 140 solar farms generate about a fifth of the UK’s solar energy, enough to power about a third of the region’s homes. By comparison with other renewables, solar farms are cheap to install, they require very little maintenance, and when they reach the end of their lives after several decades, they can be removed relatively easily.
At present, the largest solar farm in our region is West Raynham in Norfolk, occupying 225 acres and generating 50 megawatts. But this will shortly be dwarfed by two approved new sites: Sunnica on the Suffolk/Cambridgeshire border, and Longfield north of Chelmsford, both of which will be ten times larger, generating 500 megawatts each. And there are at least three larger proposals in the planning process.
Growing resistance
Solar farms are very conspicuous – and not always welcome – features of the landscape. Resistance to them has been growing, and not only from climate-deniers. Perhaps the most critical issue is that they are taking good farmland out of food production at a time when we are trying to become more self-sufficient. This is an understandable concern, though solar farms currently cover only 0.1% of the land in the UK. Current plans would only expand that to 0.3%, though that might be rather higher in East Anglia. Supporters of solar developments argue that climate change, which solar farms are designed to address, is a greater threat to UK food production than solar farms. They also point our that the damage to farmland is not permanent, and that they can increase biodiversity.
A solution?
But there is an answer to this concern. We do not need to lose this land for agriculture, and in many European countries this problem is already beginning to be solved by “agrivoltaics”, a technology where the UK lags far behind.
Agrivoltaics combines solar generation with farming on the same land in three broad ways. The first and simplest involves allowing poultry or sheep to live under conventional solar panels. The animals keep down the grass, which otherwise might have to be controlled to reduce fire hazards. The second is to raise the panels so that more conventional farming can continue underneath. The third and most expensive involves raising panels on a mechanism which allows them to be tilted to allow farm machinery to operate underneath.
Benefits: food and energy
Round the world, there has been progress on the second model, and researchers have found substantial advantages. Although all plants need sunlight to grow, many suffer when exposed to fierce direct sunlight. The light shade provided by the panels avoids this, creating a healthier microclimate, and the panels also protect the crop from heavy rain, wind and snow. The result has been improvements in crop yields averaging 20%, and higher for some crops. The panels also reduce evaporation from the soil, meaning that crops require less water, in some cases a reduction of more than 20%. Research is now investigating the use of semi-transparent solar panels, which can filter sunlight to allow specific wavelengths, appropriate for the particular crops growing below.
There are advantages in energy generation too. In Europe, agrivoltaic sites generate an average of 8 MWh per hectare annually. And they are more efficient than ground mounted panels. This is because solar panels are most efficient if they are kept cool. As they grow, the plants give off water which evaporates, cooling the air above. Studies in Oregon have found that panels assisted like this can generate 10% more electricity than the same panel mounted conventionally on the ground.
Naturally, the advantages are most marked in hot climates, where crops need a lot of water, and plants suffer from midday scorching. However, the benefits have also been demonstrated in more moderate climates like the Netherlands, and as the climate warms, they will become increasingly relevant.
The UK lagging behind Europe
The idea of agrivoltaics was first proposed in Germany in the 1980s, but the first country to take it seriously was Japan in 2004. Since then, it has become widespread in Europe and the USA. The current EU Solar Energy Strategy encourages Member States to provide incentives for it, and 14 have done so, including Italy, France, Austria and the Netherlands.
Worldwide, there are currently at least 1,000 agrivoltaic systems in operation, with most in China, the USA and Japan. The International Energy Agency, estimates that the global capacity of agrivoltaic systems will rise from 2 gigawatts today to 100 gigawatts by 2030.
However, at present there is no commercial agrivoltaic farming in the UK.
Issues
As always with innovations, there are trade-offs. Agrivoltaics keeps the land in agricultural production, and in some cases may even increase crop yields, but raising solar panels more than 3 metres above the ground must mean a significant change to the landscape, which is likely to face opposition.
Agrivoltaics are not appropriate for all crops. Many leafy crops, root vegetables, and beans benefit, but cereals require full sunlight. In the Netherlands agrivoltaics are being used at scale to grow raspberries. In South West France winemakers, experiencing warmer summers, have successfully used it for grapes. There, controlling the level of sunlight prevents the grapes developing too much sugar for good wine production.
Large agricultural machinery cannot easily fit under solar panels, making it difficult to tend to crops. This can be solved by mounting the panels on high frames (perhaps 5 metres), or installing frames that rotate to let tractors pass. However, these kinds of measures are expensive to implement.
At least in the early stages, a move to agrivoltaics will require government support. This is possible under the Improving Farm Productivity (IFP) solar grant in the UK, which can cover 25% of the capital costs, up to £100,000. But to date, there have been no plans to use these funds for agrivoltaics.
Why are we missing the boat?
The UK is clearly lagging in this technology behind much of Europe. Yet the advantages are clear, both economically and politically. Agrivoltaics may not work in every location, or for every crop, but when the benefits have been proven in countries with similar climates, it does seem absurd that nobody is trying to make it work in Britain. And for the big, and potentially controversial, proposals still being prepared, this might help alleviate some of the likely opposition.
