The development of our solution of crop and photovoltaic combination
At the start of the Sun’Agri program a PhD student studied a fix agrivoltaic system within UMR System of INRA Montpellier SupAgro. Hélène Marrou studied the impact of shade brought by a system composed of fix photovoltaic panels over a cultivated plot. Her work included several plant species and variety, from cereals to vegetables over several seasons and with several degrees of shade.
The main findings showed (Marrou, 2012):
- In condition of full density of the panels (60% of shade = power station or traditional photovoltaic greenhouse), yields are considerably reduced (about 40%)
- In condition of semi-density (30% of shade), some crops have maintained their yield or even increased it compared to control crops (without panels).
Besides, the works have also shown that:
- Atmospheric conditions (wind, humidity and air temperature) have not been disrupted. Temperature at ground level are however cooler (during the day) under the photovoltaic panels, due to a reduction of sunshine on the ground and the cooling down of temperature at night may be limited by tilting the panels completely horizontally during the night;
- Evapotranspiration reduces dramatically (and therefore water consumption), from 20 to 30%, under the panels compared with the control crop in open field.
These experiments have however shown that a fix system cannot guarantee that yield are maintained or increased. A certain flexibility has to be added to the system by allowing it to select times of shading and of full sunshine. This is made possible thanks to the rotation of panels and is called dynamic agrivoltaics. Thus, after these works, a second phase of the program was launched in order to improve the system and most specifically the crop yield.
Dynamic agrivoltaics consists in modulating shade brought to crops thanks to mobile photovoltaic panels fitted on trackers according to the physiological needs of the plants. To do so, the structure and a tracker system have been specifically developed. The priority of the system is the crop, the photovoltaic production coming second.
During the second phase of the Sun’Agri program two PhD thesis have developed two aspects: the modelling of the eco-physiological development of lettuce and a water balance model under dynamic agrivoltaic system.
The development phase of the program has been concluded and the demonstration phase has started to:
- Demonstrate on a larger scale and in real conditions the impact of dynamic agrivoltaics on various high added-value crops
- Extend the research to a variety of crops and climate
- Develop additional products
- Prepare agrivoltaics benchmarks and good practices
One of Sun’R’s objectives is to create an agrivoltaics research unit, a first in the sector, which will be the international leader on project combining crops and solar energy.
Consult our Sun’Agri offer to participate in an agrivoltaic project