Agrivoltaics

6 min read

Introduction

Some crops grow well in woodlands, requiring moderate access to sunlight to do well. Such crops include raspberries, blackberries, gooseberries, pecans, hazelnuts, and currants. These crops still need to grow in soil, at least for the foreseeable future, due to the strong character that particular soil types imprint on the fruit and byproducts.((Current research suggests that based on where wine grapes are grown, the wine flavor is markedly different. Wines produced in South Africa and France, for instance, are different not only because of the climatic conditions (which are in any case, quite similar) but also because of the soil differences in both countries.)) Agrivoltaics primarily targets these crops. Agrivoltaics is a technique that uses translucent solar modules as cover for the plants on farms. The panels produce energy while providing shade to the plants growing beneath them.

Agrivoltaics

Agrivoltaics does not facilitate the sort of controlled environment that would be seen in a high-tech greenhouse or vertical farm. Instead, it provides cooler temperatures inside farming areas by reducing radiation during the day and, consequently, the process of transpiration. In recent years, many countries have started experiencing more extreme weather conditions.((For instance, global wheat prices jumped due to a prolonged and unusually hot summer in 2018. Forecasts predict similar weather patterns in the future.)) Summers are hotter and last longer. Springtimes have lower precipitation and are shorter. Winters are particularly harsher, with several days of subzero temperatures in many countries. Plants that do not do well in extreme temperatures have borne the brunt of these adverse weather patterns.

Trends in agrivoltaics

While agrivoltaics as a concept has been around for some 40 years, it has only recently started gaining supporters. This is mainly due to changing weather patterns around the world that threaten future food supply and the growing popularity of solar power as a sustainable way of powering the world in the future.

Scientists have identified particular plants, including grass that can do well in the shade. These plants can effectively feed animals because they have high nutritional value. This means that rotational farming can easily work on farms with photovoltaic panels. For instance, Hawaii sheep farmers have devised a means of keeping sheep under solar panels, and subsequently farming the land. To ensure this is workable, the farmers use specialized machines that are adapted to these environments. Such adaptability allows for automation and enables the farms to become economically viable.

Despite their attractive results for plants and animals, agrivoltaic farms offer little temperature manipulation in terms of increasing temperatures. This means that, at night and during the winter, they may not offer the same capabilities as other forms of controlled environment agriculture. Therefore, assuming that these farms are expansive, the power generated by the solar panels—which incidentally increases when plants are growing beneath the panels—must be stored for use in powering homes and the farm, especially when adequate sunlight is unavailable. Acquisition and installation of such storage facilities cost a fortune. Lack of such facilities, on the other hand, results in lost power.

Agrivoltaics has so far shown good results and future potential. The power produced can be applied to other uses, while better adaptation of farms can help in soil regeneration and permaculture. This technique also has significant weaknesses, including the narrow range of environmental conditions that it can manipulate and how it can manipulate them.

Agrivoltaics and permaculture

In its simplest definition, permaculture is a form of land management, in which farming and human settlements are designed in a way that does not negatively impact the ecosystem. Modern farming practices are highly destructive to the environment. They lead to soil pollution, deforestation, and desertification. The use of land for a single need is particularly detrimental to the soil. It strips the soil of essential nutrients. To make up for it, farmers replenish the nutrients artificially. Solar farms have at the same time become an essential part of the green energy conversation, with such farms being installed in areas that receive ample sunshine.

Agrivoltaics

The Templin Solar Power Plant in Germany is the world’s largest thin-film power plant, covering more than 500 acres in Brandenburg, Germany. The plant generates enough power to power 36,000 households in the state. Brandenburg is a heavily agricultural state, with agricultural land covering 45% of the state.((10% of the entire state is permanent grassland, while 35% consists of cropland. Agriculture is highly mechanized in the state, though it has been making decisive steps towards producing organic food – 12% of the agricultural land is dedicated to organic agriculture.)) We can safely assume that the state while striving to be green, has wasted 500 acres of prime agricultural land that could have been leased to local farmers. Farming and rearing animals beneath the solar panels would increase power generation, enhance soil health in an area that served as a military base, and create additional income. Such a set-up in which the environment and human needs are met is the essence of permaculture.

Advantages of agrivoltaics

  • Improved production – Initial results show that a selection of plants that do well in the shade have had significant improvement in yield when grown on agrivoltaic farms.((Potato production with agrivoltaic systems has shown marked improvement in yield and quality. The same is not true for winter wheat, however, with poorer production when farmed in the shade. This could be an indication of the narrow range of plants that can do well in such an environment.)) The plants normally grow in the shade, with minimal access to direct sunlight. They are not badly affected by frost or moderately cooler temperatures at night. Therefore, there is no need to offer the sort of protection that greenhouses and vertical farms provide.
  • Rotational farming possibilities – With access to farm machinery that has been adapted to work on such farms, it is possible to rear animals and later farm crops. This enables farmers to achieve proper crop rotation.((One such grass species is buffalo turf, which has been shown to reduce the spread and impact of the pathogenic palmetto virus. The grass is also very good for eliminating weeds on previously farmed land, while it can also be removed easily when the time comes to cultivate again.)) As soil regeneration experts appreciate, keeping animals on land that is lying fallow and farming it moderately by avoiding excessive tillage help build up the topsoil at a much faster rate.
  • Power generation and synergy – Solar panels generate enormous amounts of energy, especially during the hotter seasons. This power could be used to power homes, with the necessary distribution infrastructure in place. However, in coastal areas, the power has been used to desalinate seawater and channel it to farms. This synergic relationship has helped increase interest in this form of agriculture, since it could be used in the future to enable coastal areas, which are normally dependent on food from elsewhere, to grow food.

Disadvantages of agrivoltaics

  • Capital intensive – All forms of controlled environment agriculture are expensive, and an agrivoltaic farm may not always make economic sense. Solar panels are likely to be more costly than a simple glass or polyethylene cover, as used in greenhouses. The resultant protection from the elements will, however, be less, in some cases negating the need for such a farm unless the power generated is considered. The power must be stored, distributed, or otherwise used to meet the farm’s needs, such as desalination, and these systems are expensive to install. Purchase and operation of machinery specially adapted to work on these farms come at a premium.
  • Unsuitable for some crops – While shade has been seen to enhance the production and quality of some crops, such as a variety of berries and even potatoes, it diminishes the return on other crops, including wheat. While some grass species do well and, therefore, make land rotation possible, most grass species need at least four hours of direct sunlight per day to thrive. This narrows the range of plants that can be grown in such a system, even though it is mostly done outdoors.
  • Not all-weather – Despite the ability of agrivoltaic systems to handle extreme heat during the summer, it is difficult to control temperatures and humidity levels during cooler months.
  • Disposal of solar panels – every few years, solar panels need to be replaced, as their effectiveness, and the batteries that store solar power depreciate. This poses an environmental headache, a problem for capital, and in many instances dilutes the advantages of agrivoltaics.

Conclusion

While this paper mainly looks at agrivoltaic systems that are mostly outdoor, such systems could also be paired with greenhouses with good results. For instance, the power generated could be used to heat greenhouses during cooler months, make greenhouses less vulnerable to accidents such as power outages, and control more elements than a traditional aluminum and polyethylene greenhouse would normally allow. If a farmer needs to control the soil and regenerate it as well, they will need to forego many of the controls that a greenhouse affords them.

Author
Mbau Tim