‘Agrivoltaics, a solution committed to the environment’
In this article, ETSIAAB professor Miguel Ángel Muñoz addresses the challenges of the simultaneous use of land for both agriculture and electricity production.
By MIGUEL ÁNGEL MUÑOZ-GARCÍA*
Spain has more solar radiation than the average of the surrounding countries. This adds significant profitability to photovoltaic (PV) installations. In addition, low rainfall levels, probably due to climate change, increase hours of sunshine and, therefore, the potential production of electricity. On the other hand, PV electricity is one of the cheapest on the market because of the continuing rapid decline in the price of PV components. The only handicap to this production system is storage. However, this limitation is likely to be improved by the electric vehicle development - which might end up being the storage medium of energy in its own batteries - together with the sharp drop in the accumulator’s price
Electricity produced by solar panels uses the PV effect, which currently converts about 20-25% of the radiation into electricity. No other system achieves this simply by being exposed to the sun (except solar thermal plants, which require large scale -functioning). Let us say that on a sunny day, 200 watts per square metre can easily be got. This amount is enough to power a domestic refrigerator. Besides, the panels emit no gases during their work, and those emitted during the manufacturing phase are offset in a few months by the clean energy they produce for about 25 years. Furthermore, the panels are made with recyclable materials, mainly such as aluminium, glass, and silicon.
Over the last decade, there has been a sharp price decrease in the cost of the solar panel, the main element of a PV installation. Its price, in many cases, has been divided by six. There has also been an explosion in demand for the installation of PV plants, which also benefited from the regulatory changes in countries such as Spain and the increase in the price of fossil fuels.
Thus, given the steep growth in the demand for ground-mounted PV systems, there is a growing pressure on agricultural land. Solar energy production competes with food crop production for land. Ground-mounted solar PV requires large areas of land. Therefore, this fact could reduce the land available for agricultural use.
Agrivoltaic (or agrovoltaic) systems might solve this problem. The term agrivoltaic, recently created and still under discussion, can be defined as combining the farm and livestock use of land with the production of electric energy. PV panels are placed on poles usually higher than usual to ease the work under them. The crop receives less sunshine due to the placement of the panels, which generally reduces crop production, but not always. Avoiding excess radiation may benefit some crops. In addition, the crop tends to adapt to the new radiation situation so that the production decrease is slighter than would be expected.
According to several research articles, these combined systems of PV panels and crops are profitable. One such study (Marrou, Dufour et al., 2013) shows that crops increase yielding under PV panel shade since evapotranspiration is reduced by 10-30% when the available sunlight is 50-70%. At the same time, water use efficiency is increased, as wider ground-covered varieties promote significant sunlight uptake and decrease soil evaporation.
Land sharing should also consider the social focus since it can help keep the primary agricultural use of land. The new electricity production use should not displace it. Nowadays, the allocation of agricultural land use is frequently changed by legislation when PV plants are installed, even when there is coexistence with cultivation (not to mention the consequences this has on CAP subsidies).
However, a correct definition of the agrivoltaic concept, one that considers the different cases arising and preserves the fundamental use for agricultural production, should not lead to significant arable land losses. At the same time, the extra contribution of electricity production would increase the arable land yield. The so-needed decarbonised economy development demands both activities. Nevertheless, this concept also requires legislation, studies and incentives to avoid the change of use. Therefore, special attention must be paid to social aspects beyond the purely economic ones. This would help not to increase the depopulation of the rural areas even more.
There is no doubt that there is still a long way to go. We must do much testing before concluding with so many cases under this new concept. Will we miss the boat again? Or, will we have learned to be resilient? Now is the time.
* Professor Miguel Ángel Muñoz-García, - Department of Agroforestry Engineering – ETSIAAB.