Pest control in solar plants

Mammalian pests in solar plants

Rabbit populations (Oryctolagus Cuniculus) and of some micromammals (rats, mice and mice) sometimes grow out of control in solar plants. Rabbits dig underground burrows next to the support of solar panels; rodents, such as the brown rat (Rattus Norvegicus) or the house mouse (Mus Musculus), take advantage of material warehouses or operating booths to nest and search for food. The photovoltaic solar plant is a safe space for prey species such as rabbits and rodents due to the absence of predators; the human presence scares them away.

The purpose of pest control is to regulate populations of species that grow out of control and cause damage to the solar plant.

For example: the destabilization of solar panels due to the excavation activity of rabbits or the interruption of the operation of solar panels due to broken wiring and electronic equipment.

Poison or predators?

The application of pesticides is not recommended to control pests due to land and water pollution, and because of the cascading effect on the food web (bioaccumulation). In fact, natural predators of pest species become intoxicated when they prey on or prey on poisoned prey, including people who eat game meat. The poison affects the environment and also human health.

Another advantage of biological control is the economic cost; the material is cheaper than chemical treatment and, in addition, it is durable.

In conclusion, biological pest control meets the ecological criteria for the production of renewable energy: a non-polluting activity that is integrated into the ecosystem.

Biological pest control measures

The basis of biological control is to attract predators — birds of prey and carnivores — of the pest species — rabbits and rodents — to the solar plant. Therefore, the objective of a biological pest control plan is to establish a community of predators in the environment of the solar plant that regulates rabbit and rodent populations.

Biological pest control measures in solar plants are:

• The revegetation of the perimeter of solar plants and the construction of stone walls: plant screens and walls are a refuge for turons and weasels, and also for large Iberian, bastard and ladder snakes, which prey on rabbits and rodents.
• The installation of nest boxes in trees, agricultural buildings or poles to establish owl breeding pairs (Athene Noctua) and common owl (Tyto Daybreak), rodent predators, inside or around the solar plant.
• The installation of perches on poles around the perimeter and in the corridors of the solar plant so that owls and owls, who hunt on the prowl, use the solar plant as a hunting ground.
• The introduction of turons to occupy rabbit nurseries and establish populations inside the solar plant. The turon is a specialist in rabbit hunting.
• Sheep compete for grass with rabbits. In addition, trampling compacts the soil and makes it difficult to excavate underground galleries. The entry of cattle to the solar plant to graze and cut down vegetation is also a measure to control the rabbit.

Chemical control

Pesticides are a complementary control measure, for sporadic and local use, and always inside the solar plant. Chemical treatment must always be justified by the level of the pest and always under technical advice. The law must be complied with; dosage, method of application, cleaning and recycling of products and containers. Priority should also be given to the use of the least toxic products. A specialized and authorized professional must design and implement the chemical pest control plan.

Designing an integrated pest plan

In Environmental Ideas, we design strategies for the biological control of pests in solar plants that, in addition, are also measures for the conservation of biodiversity.

First, we inventory the surrounding community of carnivores and birds of prey to guide habitat improvement measures and establish a community of predators in the solar plant. We also map the elements of the landscape in the solar plant and the environment (trees and hedges, dry stone walls, agricultural buildings) and adapt them. We then design habitat improvement measures; we take advantage of landscape elements and we also incorporate other artificial ones (for example, artificial nests and perches or walls and hedges) for predators to shelter and hunt in the solar plant. The objective is to increase the mortality rate of pest species due to predation inside the solar plant: to turn the solar plant into a hunter for carnivores and birds of prey. And to evaluate the effectiveness of pest control measures, we estimate the mortality rate of pest species due to predation (analysis of egagropylae and excrement), the trend of rabbit populations (distance sampling: DISTANCE) and rodents (marking-capture-recapture), and also of the predator community (wildlife tracking and phototrapping) in the solar plant and the environment.