Digital edition energía eficiente de hoy – Pages 22- 25

 Energy policy, due to the urgent need to curb climate change, is betting on renewable electricity generation. In this context, photovoltaics plays and will play a relevant role. However, to achieve the objectives set by PINEC (30 new GW and 20 billion euros of investment) it is necessary, in addition to taking advantage of the roofs of buildings and warehouses, to build solar fields on the ground. But this can conflict with the use of these lands for agricultural or livestock uses. Agrovoltaica emerges as a solution for both activities to coexist satisfactorily.

Paqui Saez

When we talk about agrovoltaica we refer to photovoltaic installations on the same land where there is a crop without the former damaging agricultural tasks and occupying the least possible space.

Precisely the Platform for a New Energy Models (Px1NME) has prepared the document ‘Agrovoltaica: adding agriculture and solar electricity’ where it highlights its advantages and shows some international examples that make clear the compatibility of both activities.

Spain has a wide area of ​​land destined for agricultural purposes, but with the emergence of solar fields, these extensions of land, in some cases, are abandoning their original use: crops.

But it does not have to be like that. There are already several projects that show that it is possible to install solar panels with crops. The simplest, go, for example, by mounting panels on the roof of a greenhouse, taking into account, those yes, adjust the density of panels according to the light needs of the plantation; or use the soil as pasture land that, in addition, serves to keep the land clean without the need to use herbicides, on the other hand, prohibited. Furthermore, the structure of the photovoltaic installation can also serve as a support for anti-bird networks.

There is great potential to jointly take advantage of the land and the sun, either by adapting to existing crops or by designing solar parks ‘ad hoc’

From Unef itself they propose that photovoltaic plants on the ground become “integral nature reserves”, adopting measures such as the installation of nesting boxes and insect hotels and the promotion of the use of the land of the installation for pasture. And above all, respecting the natural formation of the vegetal layer, ensuring that the prohibitions on the use of herbicides are complied with and opting for a fence that allows the passage of birds and other animals, avoiding the fragmentation of the natural habitats of local species. And they remember that “the good choice of the location in the design phase of the plant is essential to mitigate the negative aspects”.

When facing an agrovoltaic project, it must be taken into account, as stated in the document prepared by the Px1NME, that the installation does not hinder agricultural tasks, occupies the minimum possible soil and that sufficient light reaches, either directly from the sun or diffuse, both to the panels and to the crops. This may require a higher structure and a lower PV density than if there were no crops.

Less light for plants can also lead to a decrease in production or delay their maturation. In addition, the panels can cause the water not to reach the entire land, which can also harm crops.

The key is to minimize the negative impacts for both parties, so from this group they demand more investment and experimentation for its promotion, although they already launch some ideas: change production for other plant species that need more shade, combine two different species in rows alternating or determining the separation between panels that balance the insolation between both activities, are some of them.

Some examples

Agrovoltaica is not yet highly developed in our country, but other countries have seen the possibilities it presents, although it is necessary to assess whether they compensate for possible production losses taking into account the increase in income from the sale of energy.

Fruit trees, vineyards, nurseries, corn and wheat crops… are some pilot experiences that are included in the aforementioned report and that are already underway in countries such as France, the United States, Japan, Germany or Italy.

The United States is one of the countries that have advanced the most in research on the possibilities of agrovoltaica.

Last year the results of the Biosphere 2 laboratory developed by the University of Arizona, an agrovoltaic facility in the Sonoran desert, were also known. The goal was to produce solar energy and grow edible plant species in the same space (they chose jalapeños, cherry tomatoes and chiltepin peppers), monitoring the entire process.

Among the most significant results they verified, for example, that the presence of solar panels reduced the temperature, direct light and the demand for water during the day. In addition, photovoltaic production benefited from the increased presence of humidity in the air.

This meant that jalapeño production was not affected by growing under solar panels, tomatoes doubled their production and chiltepines tripled it, reducing water loss through perspiration by 65% ​​and humidity was maintained for more days.

Also in this country, the Innovative Site Preparation and Impact Reductions on the Environment (InSPIRE) project has been developed, with which it has been seen that agricultural crops under the shade of solar panels use water much more efficiently and protect plants from worst of the midday heat.

Agrivoltaic is likely not viable for large-scale monoculture farms that rely on heavy machinery. But preliminary results already suggest that it can significantly increase the yields of certain plants. Perhaps most importantly, low-impact solar development can make solar projects more responsive to the priorities and concerns of local communities.

Although it is not yet well developed in Spain, we have been able to learn about some initiatives in our country, such as the two photovoltaic parks in Julià (Gironés) and a third in Folgueroles (Osona), which is being developed by the Green Concept Management company, with an investment that around 20 million euros and with an electricity production equivalent to the energy consumption of 12,000 homes.

Solutions for a better coexistence

Normally the photovoltaic panels are fixed, but if one opted for two-axis adjustable panels, controlled by a computer program, adjusted to the needs of each case, photovoltaic production could be maximized while adapting to the needs of crops depending on the weather conditions of the moment.

Variable inclination bifacial panels are another ally in order to adapt solar panels according to the needs of the crops, since they allow a totally horizontal positioning and avoid shadows when necessary.

The market has also developed specific panels for this type of installations such as special monocrystalline solar panels for five agricultural pilot projects in the Netherlands for five different crops: blueberries, red currants, raspberries, strawberries and blackberries. These are weatherproof 240W glass-glass panels with different levels of transparency. Transparency is a fundamental aspect in this type of project, since the plants that are under the panels need to receive enough light, but neither that it strongly affects the fruits.

There is, therefore, great potential to jointly take advantage of the land and the sun, either by adapting to existing crops or by designing ‘ad hoc’ the solar parks and the type of crop they are going to produce, reducing to a minimum the possible negative effects for both parties.

The Green Concept Management initiative
The Green Concept Management company is going to start up two photovoltaic parks in Juià (Gironés) and a third in Folgueroles (Osona), with an investment of around 20 million euros and with an electricity production equivalent to the energy consumption of 12,000 homes.
The forecast is that the construction of the first park, that of Juià, can begin at the end of this year and be connected to the network next spring, while the phased operation of the other two parks has also been scheduled to complete the entire process in the first quarter of 2022.
One premise for this company is to preferably take advantage of land for its parks that have undergone a certain landscape degradation (areas close to power lines, highways, industrial areas). For this reason, the first two photovoltaic installations are located near the Juià electrical substation (with a power of 4 and 6.8 MW respectively) while the third site is next to the Folgueroles high voltage lines (in an area farm in which there would be four photovoltaic complexes that would add between 12 and 16 MW).
The promoters pay the owners of the rented land a fee of 3,000 euros per hectare per year to dispose of the place in exchange for giving up the PER. “The aim is to improve farmers’ incomes by dispensing with subsidies,” says Guy de Maillé, head of Green Concept.
They also offer an economic participation of € 1,500 per MWp per year to the nearest agricultural cooperative or for the city council to develop an activity that favors global sustainability. In the case of Julià, the city council has decided that it will use this participation for a door-to-door garbage collection plan and its respective recycling.
In the philosophy of this company is the creation of a complete agricultural activity to favor local agriculture and grow in BIO mode products that will be sold in the markets closest to the agrovoltaic field. This activity will take place between each range of bifacial panels mounted on monoaxial and distant axes of 8.8 meters each. Thus, 4 meters of the 8.8 will be used to do permaculture. The rest will be used for animal maintenance according to 4 per 1,000 to optimize the regeneration of the land by mixing sheep and chickens. In the areas that allow it, they will try to put hives at the end of each range and thus participate in the safeguarding of a species that is dying out.

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