The Experiment is not to be overlooked: in the Midst of the hills, perched high on a field of the living and working community Heggelbach in the German Baden-Württemberg ink blue shimmering solar panels on eight-Meter-high steel stilts. The stands are so high that the organic farmers with tractor, combine harvester and harvesting machine including drive can.
How good is wheat, potatoes, clover grass and celery thrive in the partial shade of the modules, want scientists to find out in a by the German Ministry of education and research funded a pilot project. The project is led by the Fraunhofer Institute for Solar energy systems (ISE) in Freiburg and has just gone into overtime.
The cooling effect by the cover crop increased the annual electricity yield.
Three Harvests, the farmers to Florian Reyer have retracted under the modules already. And Reyer is satisfied. To curves other than the PV free comparison surfaces to the steel bars around, and the wheat and potato yields were down after the rainy summer of 2017, almost one-fifth smaller. “But this is an order of magnitude, we can live well,” he says.
Also this year, losses are, at least in the case of three of the four field varieties of fruit. The evaluation was not yet completed, it is said, from the University of Hohenheim, which is also involved in the project. In the summer of 2018 after all, there was the sun-loving wheat, an increase of three per cent, in potatoes and celery, there were about ten percent.
field workers and regions that would benefit
The world’s population grows – and thus also the demand for food. At the same time, surfaces will be used for the production of green electricity, to curb the climate crisis. The combination of agriculture and PV , also agro-photovoltaic called, could defuse this conflict. A calculator should not be fitted a percent of global agricultural land with solar panels, in order to satisfy the power hunger of the world: a Team of Oregon State University recently reported in the science magazine “Scientific Reports”.
In very hot regions with high solar intensity, the concept pays for itself, especially as scientists to Greg Barron-Gafford, University of Arizona, in the September issue of the magazine “Nature Sustainability” reported. On a test area in Arizona they had planted in the shade of the modules Chili, Cherry tomatoes, and Jalapeño.
The plants could provide regions with electrical power , have no access to public electricity networks.
The Chili harvest fell three times and the tomatoes from harvest twice as high as the PV free comparison areas. Jalapeños thrived anywhere. After irrigations, the moisture remained longer in the soil, and the water consumption was low. The solar modules are benefited and approximately nine degrees Celsius at the cooler as modules of a classical free-standing facility in the same Region, reported Barron-Gafford. The cooling effect is increased efficiency, and increased the annual electricity output of about one percent. “All in all, a Win-win Situation,” says the researcher.
Hélène Marrou from the French agricultural research Institute Supagro holds sub-Saharan Africa and tropical Islands for the most suitable locations for agro-photovoltaic, as she also writes in the magazine “Nature Sustainability”. The solar modules are not improved plants only the micro-climate for the culture. Also, the field workers benefited from the cooler air under the modules. And the plants could provide regions with electrical energy, with no access to public electricity networks.
However, farmers are only rarely able to meet the costs for purchase and maintenance. “The demand is therefore economic studies on the ethical Design of contracts between land owners and solar investors,” says Marrou. On the other hand, it can be in temperate zones and the Northern countries, especially important to regulate the agro-photovoltaic strictly, in order to maintain sufficient food to be produced.
Long pay back time
This challenge, the researchers from Freiburg and Hohenheim, see. You elaborate, therefore, just standards, which define the rather vague concept of agro-PV and the criteria for eligible concepts are good. In June 2020, the ISE researchers want to present to the global first international conference on agro-PV in France your suggestions. “You could set, for example, that an agro-photovoltaic area must provide at least 80 percent of the revenues of a photovoltaic-free comparison area to be retracted. It is, for example, in Japan,” says Max Trommsdorff from the Fraunhofer ISE.
Or to put, in the US state of Massachusetts, a minimum percentage of light that must penetrate to the floor.
Economically, the agro-photovoltaic is not a self-runner. Although the modules in the German pilot project, the solar cells on the top and the bottom, a catch so the floor mirrored the sunlight and deliver, according to the ISE, approximately 15 percent more power than conventional facilities. But in the case of the so-called levelised cost of energy, which include investments, operation and maintenance, to beat, especially the high, steel sub-structures are difficult to book. “For the average equipment of a capacity of about two megawatts, we expect electricity generation costs of about eight to ten Euro cents per kilowatt-hour,” reported Trommsdorff.
additional benefits for farmers
Thus, agro-PV is cheaper than small roof-top systems, but more expensive than free-space PV, where the solar modules are closer to each other and at a much smaller Steel structures. Without state support, as they are called in France or in Japan already, amortize agro-photovoltaic plants in accordance with the ISE-estimates only after 20 to 30 years – so only towards the end of their term.
In Germany, there is a further stumbling block for the Mix of solar power and crop harvest. Because the affected areas to lose the Status as arable land, and agricultural subsidies are eliminated. “That should change, in order to make agro photovoltaic system more attractive,” calls Trommsdorff.
also concepts that benefit farmers an additional, for example, in fruit growing could Help. Roofs of PV would deliver in an Apple orchard only electricity, but also against sunburn and hail protect. The expensive steel racks could also turn out to be lower. “And you would not intervene here in some regions also aesthetically into the landscape, because many of the Apple orchards are already covered now with anti-hail nets or plastic foils”, says the ISE researchers. The concept was soon to be tested in practice.
Meanwhile, produced the pilot plant of the living and working community Heggelbach more green electricity. The organic farmers use about 70 percent of yourself, store it in batteries, and “refuel” in order, among other things, an electric car, a forklift, the milking and cooling equipment. What is left of the food into the network. The energy consumption for their production, the solar system has retracted, according to ISE-information after three to five years. After that, you are probably making 20 to 30 years, a contribution for climate protection. Bauer Reyer hopes, therefore, that the example and the policy creates the conditions for it.
Created: 29.10.2019, 17:45 PM
